1988 Isuzu Trooper diesel conversion

Shakedown

2010-02-27T23:05:00.003-06:00

Since the last post, the clutch has been replaced. The kit included a heavy-duty clutch, pressure plate and release bearing (from Sunbury Brakes in Australia, here is the kit).

Since the kit did not include a pilot bearing, I had to find one on my own. It turns out that the pilot bearing from the stock gasoline Trooper engine is the same, so I used that application to order a new one from NAPA - works without issue. The transmission input shaft, release lever, release bearing, bearing retainer clip, etc. are all the same between the gas and diesel transmissions. I ordered a rear main seal from an Isuzu industrial dealer, giving them the engine model as the application.

Two problems have grounded the Trooper since the clutch was replaced. The first was a fuel starvation issue, which I traced to the sock filter I had added to the bottom of the fuel pickup tube I fabricated in the fuel tank. I had to remove the tank, pull the pickup assembly and remove the filter, which was completely stopped up. I think the biodiesel melted it a bit, as it seems to be made of nylon. I just left the pickup tube bare - I have a prefilter installed before the main filter/separator assembly, and any junk that comes up from the tank will be caught in the (very cheap and easily accessible) prefilter. The sock filter was meant to protect an in-tank electric fuel pump from debris; not necessary in this application. I also took the time to repair the wiring for the fuel gauge, and I now know how much fuel I have in the tank.

The second problem was a very sudden loss of heat on the freeway. I exited and pulled over, and quickly confirmed my suspicion that I had lost all coolant. After towing the truck home and inspecting the cooling system, I found that an expansion plug (also known as a freeze plug or frost plug) had fallen out of the block.

This was the same plug that had popped partially out a couple of winters ago when I had inadvertently left some water in the block (thought it was drained totally; I now will always leave antifreeze in the system, no matter the circumstances). I tapped it back in at that time, but I guess it was crooked or damaged.

Luckily, this particular plug is the easiest one to access on the entire block - between the starter and injection pump on the driver's (or left) side of the engine. Determining what size plug to get was the most time-consuming part of replacing it - while the plug is the most accessible, access isn't all that great, and I couldn't get any sort of measuring device close enough to get a reading. I tried to order the plugs from the stock gas engine block, but they were too small. I finally found a website with parts diagrams of the block (see here) and was able to determine that the large plugs are 45mm in diameter. Of course, no local parts houses had a plug this size.

Mr. Lemond, Isuzu parts guru, sent me a stock Trooper diesel plug (C223 engine from '86-'87 also has 45mm plugs) as well as a block heater made for this size opening. I was able to install the block heater by carefully choosing the angle of installation (the plug is behind the oil pressure sender and the fit is tight - the electrical connector has to be at about 1 or 2 o'clock to clear it). I also had to remove the oil pressure sender in order to access the area, and tapped the block heater in by using long socket extensions inserted through the fender skirts in the driver's side wheel well. Once it was tapped in (to seat the o-ring), I tightened it from the same wheel well location.

Installing the oil pressure sender was tricky. I had to trim a small amount of rubber off the end of the heater's electrical cord to gain some additional clearance. I then inserted the cord, and spent a great deal of time trying to get the sender's threads started, as it was rubbing on the electrical cord connector. Once it was started, it went in smoothly, and there may even be a hair's breadth clearance between the cord and the body of the sender.

On balance, I am glad the plug fell out, as it gave me an excuse to install a block heater, something I have been meaning to do for some time. I am glad there was no damage to the engine when the coolant was lost. I've driven it a bit since then and all seems well - must be the cool-running diesel and overall ruggedness of the 4JB1-T that saved me.

On the road

2009-09-08T21:53:00.002-05:00

After the hood was completed (except for the awful rust repair at the front edge - I will be smoothing this out soon), I plated and insured the truck. I also adjusted the front suspension, as it was bottomed out from the added weight of the diesel engine. Next was a trip to the exhaust shop, and the trooper now sports a full turbo-back 2.25" exhaust system, which sounds great (I will try to get some photos of this later). Finally, I spent a good deal of time cleaning the carpets and the interior generally, as it was pretty filthy from farm use and neglect. It's quite nice now.

I also realized the clutch is junk, and am wishing I had changed it when I had everything apart. A new clutch kit arrived from Australia last week, so I am now going to remove the transmission to install it, along with a new rear main seal. After that, it's down to some wiring cleanup and tightening the drive belts for immediate tasks. There will be some more rust repair a bit later (rear doors), but that can wait a while.

I can say it's a lot of fun to drive - good response, lots of torque (when I can get it to the ground). More later once the new clutch is in.

Intercooler hood scoop installation, pt. 4

2009-09-08T21:50:00.003-05:00

Intercooler hood scoop installation, pt. 3

2009-09-08T21:46:00.004-05:00

Intercooler hood scoop installation, pt. 2

2009-09-08T21:40:00.005-05:00

Intercooler hood scoop installation

2009-09-08T21:08:00.005-05:00

Over two years and no updates - the project continues, despite some setbacks to the schedule.

An attentive reader might recall a post from the distant past detailing the intercooler hood scoop I imported from Australia, which arrived with the surrounding hood attached (the entire assembly was cut free from the hood with a saw). I have finally gotten around to installing the scoop, details below.

The hood structural supports are different on a hood with an intercooler scoop; instead of meeting at a center crossing point as they do in a normal hood, the main supports are cut and two new members are fitted which avoid the hole punched for the intercooler. Additionally, there is a steel ring which fits into the cutout, providing the bolt-on mounting for the rubber sealing gasket. The scoop itself is fiberglass and attaches to the hood with studs from the underside. The scoop is centered on the hood, while the hole beneath is offset to the passenger side to match the location of the intercooler.

To install the scoop onto my hood, I drilled out the spot welds securing the two structural members, their support gusset plates, and the sealing gasket attachment ring on the imported hood section (after disassembling everything and removing the scoop and gasket).

I then removed the rearmost structural member from the hood section by cutting it away near its attachment at the panel's outer skin. What was left was the skin of the hood section, which I used as an overlay on top of my hood to scribe the locations for the bolt holes and intercooler cutout. I also used the structural members I removed to scribe the cuts to the members on the underside of my hood, as well as to scribe locations for holes to be cut in the rearmost structural member to allow access to the studs which secure the scoop.

With everything marked, I cut the structure away on my hood using a cutoff wheel. I then marked the location of the hole for the intercooler with tape and cut it with the wheel, finishing the radiused corners with a die grinder. I also used a hole saw and die grinder to cut holes for the scoop mounting studs in the rear structural member (nearest the cowl).

The replacement structural members were then attached to the hood using panel adhesive and tack welds (to mimic the spot welds; technically these are probably rosette welds). Using panel adhesive, available at paint/body suppliers, is important so that the skin of the hood stays tied to the structure. This is how the factory constructed the hood, so I thought I should imitate the procedure.

Following that, the sealing gasket mounting ring was tacked to the upper side of the hood and the scoop mounting holes were drilled and adjusted with a die grinder to fit. I also did a quick job of painting the welded areas and cleaning things up a bit.

The scoop was then bolted into place with some silicone sealant instead of the foam gasket I found underneath it on the imported hood section, and the hood was reinstalled.

I am happy with the result, although my measurements were slightly off to one side and it's not perfectly centered. Someone else might not notice unless it was pointed out to them, though, as it's really close.

Fuel tank installation, pt. 3

2007-06-28T22:37:00.001-05:00

A few more shots of the tank installation.

Fuel tank installation, pt. 2

2007-06-28T22:17:00.000-05:00

The solution to the filler neck dilemma was to fabricate a tube to connect the new tank to the (shortened) original rubber fuel filler hose.

I began by ordering a piece of 1-3/4" I.D. mandrel-bent mild steel exhaust, something called a J-bend. This piece of tubing is used by custom header and exhaust fabricators and features a 180-degree bend and two legs of different lengths.

Next, I took a number of measurements of both tanks to determine the location of the filler necks on each. I used one of the mounting bolt holes on the tank flange as a reference point, as these holes were the same on both tanks. Using a straightedge and a long screwdriver (through the bolt hole, to obtain a reference line) I was able to measure the location of the necks fairly accurately.

These measurements were then used to generate a CAD drawing of the two tank necks. Additionally, I drew the J-bend and the rubber filler hose. All of this information was used to determine the best way to use the J-bend to connect the existing filler hose to the new tank. The CAD drawings were then printed and used as full-scale patterns to cut the J-bend, weld the pieces together and to cut the filler hose.

The filler hose was cut just after the first right angle bend (just as it begins to travel sideways after dropping from the gas cap area). The J-bend was cut into sections and tack-welded into an S-shape for initial fitting. After determining that the fit between the frame and bed support channel was too tight, I flattened the tube a bit in the middle in order to get it to fit. I also purchased a Gates universal 45-degree bent fuel filler hose, as I needed the 45* bend to connect the tube to the new tank's neck, which is at a more upward angle than the old neck.

My clumsy welding caused a burn-through during finish welding of the tube, so I coated the entire junction with J-B Weld to seal it. The final fit is extremely tight, but it works - leak free, so far.

The other difference was in the location of the overflow pipe. I had to bend it slightly sideways to get it to clear the body bed support channel, then buy a length of 1/2" I.D. fuel hose to connect it to the filler cap (the old one was too short).

Fuel tank installation, pt. 1

2007-06-28T21:59:00.000-05:00

The fuel tank I removed from the Trooper had very old gas in it. As a result, semi-solid residue was being drawn into the fuel filter, clogging it. I had tried to clean the tank, but it was obvious that there was a substantial amount of residue in the tank.

My options were to either have the tank professionally cleaned (quoted at $300 and up), keep replacing fuel filters until the problem went away ($25 each) or replace the tank with a clean one ($200). I decided to go with option 3 - that's the cost of 8 clogged filters, something I thought possible based on the condition of the old tank.

The problem: the new tank was not quite the same as the old one. Aftermarket tanks were no longer available from the suppliers I contacted, so I went with an OEM unit. It seems that changes were made at some point, however, as the new tank differed slightly from the old one. The main change was to the fuel filler neck location: the new tank featured a centered neck, while the old tank's neck was located toward the rear and angled back. This difference meant that the old fuel filler hose would not connect to the new tank, leaving me with no way to fill it.

Fuel system

2007-06-25T22:37:00.000-05:00

As the 4JB1-T injection pump is on the driver's (in North America, at any rate) side of the engine, the factory gasoline fuel line termination at the passenger's side frame rail near the firewall had to be addressed.

I had initially run rubber hoses from the factory hardlines up and over the firewall, down the fender and to the filter/primer pump assembly. In search of a more permanent solution, I decided to install steel lines in place of the rubber hoses, following the same route.

The new lines are formed from 6' lengths of brake and/or fuel line and are secured along part of their route by the factory clips (one of which used to keep the clutch line in place when it ran across the firewall; the other was empty), one new bracket (connected to the cruise control actuator mounting holes and running up the firewall) and a few rubber line clamps.

The new steel lines connect to the factory fuel supply and return lines at the passenger- side frame rail with short lengths of rubber hose, and to the filter/pump assembly with loops of hose. I am not terribly worried about the proximity to the exhaust where the new lines meet the factory lines; although it is close, I plan on fabricating a heat shield if necessary.

Braking system rebuild

2007-06-25T21:56:00.000-05:00

After hard farm use and two years of sitting outdoors, the brakes on the Trooper were in poor condition - the calipers were seized (along with their mounting bolts), the rotors were rusted, the pad friction material had separated from the steel backplate, and the fluid was completely black.

I repacked the front wheel bearings and locking hubs, replaced the grease seals, had the front rotors machined and installed a new set of calipers and pads.

The rear brakes received similar treatment: new rotors, calipers and pads. I also lubricated the parking brake cables and pivot points, replaced one of the parking brake cables and adjusted the system. Fresh fluid completed the rebuild.

Scoop

2006-10-04T22:57:00.000-05:00

After many failed attempts, I've finally gotten my hands on a genuine Isuzu intercooler hood scoop. A few private parties fell through (I was trying to get someone from New Zealand or Australia to ship me a scoop) and more than one supplier refused to help.

Only one outfit, All Four X Four Parts in Australia, was willing to sell me the parts. They did a fantastic job, cut the scoop free with part of the hood and all the mounting hardware intact, and even included the sealing gasket. Great guys to deal with. Check them out online.

Now I need to weld it into the hood...

Heater hoses

2006-10-04T22:33:00.000-05:00

As delivered, the heater hoses on the diesel engine appeared intact. Closer examination revealed that they were both torn and in need of replacement. Both hoses are shaped units, unavailable in the USA (at least, one cannot walk into a parts supplier and order hoses for this application) and, after my experience trying to find a lower radiator hose, I was in no mood to try and find something that would work from another vehicle.

The solution was to duplicate the more complicated bends in copper plumbing pipe and use standard 5/8" heater hose for the rest. All that was required beyond the copper shown above was a straight length of hose and one 90* bent rubber hose, which should be easy to find in a parts catalog.

The main issue was finding a way to duplicate the bead found on the end of factory steel hose connections, which is present to prevent the hose from popping off. I used a flaring tool to create a single flare in 1/2" copper plumbing pipe (the 5/8" die works perfectly for this, don't ask me why) and then employed a combination of 90* elbow fittings, T-fitings and 5/8" copper repair sleeve to create the tubes shown above. The flared 1/2" pipe fits into the enlarged areas of the elbows and Ts, and those oversized sections are the perfect size for the I.D. of the heater hose.

The T-fittings are present to allow for the future plumbing for the SVO heating tank and possibly a coolant heater for winter starting. They are closed off at this time with plugs (one shown above left) and a short section of hose.

Coolant leak

2006-07-15T17:24:00.000-05:00

After filling the radiator for the first time a few weeks ago, I immediately noticed a large coolant leak coming from somewhere near the alternator, under the A/C compressor (this was why I filled it with water initially!). I had other things to do and so let it be for a while. I was able to repair it today, or so it seems... it has not yet been pressurized, but it doesn't leak during filling like it used to.

I removed the A/C compressor and was able to spot the leak - coming from the water pipe connection at the block. These types of connections employ a metal pipe with an O-ring around the end, slipped into a machined area of the block (in this case, a bolt-on water neck) and secured with a bolt. I've seen similar designs used by Honda. In any case, this water pipe runs from the block, loops around the alternator and becomes the lower hose connection underneath. It is similar to the water pipe found on the 4-cyl. Isuzu Trooper gas engine in this regard.

I removed the two bolts, one at each end of the pipe, which secure it to the engine. I also removed the alternator heat shield which bolts to the pipe - one of the mounting tabs is visible in the photo. I could then pull the pipe out of the water neck. The alternator has to be removed to get the pipe out completely, but I was able to work with it pulled back and to the side. I cleaned the water neck surface with some emery paper and cleaned the pipe's O-ring groove with steel wool, replaced the O-ring (I used a spare O-ring that came with my Wix fuel filter for this project - the O-ring is meant to seal the sedimenter at the bottom of the filter) and re-assembled the water pipe. Common O-rings available at the local hardware store would probably have worked as well.

No leaks after an initial filling of the system; it remains to be seen whether it will hold under pressure, but I feel confident that it will.

Oil filter

2006-07-15T17:12:00.000-05:00

Finding an oil filter for the 4JB1-T engine was a bit of a hassle. Apparently, older versions of this engine used a filter identical to the one used on the Isuzu C223T, the diesel available in the Trooper in the USA. My engine, however, required a different filter with rather strange specifications. The center hole is 26mm wide, making it difficult to match.

I found a page which listed a few different part numbers (go to the 'workshop' link and select 'part numbers') but none of them crossed over to any North American manufacturers. A 4x4wire member then found this page, which again lists a few different options plus an OEM number. Here is the 4x4wire thread discussing this.

I called my nearest Isuzu industrial dealer and was able to order filters based on this number. Apparently, no other Isuzu filters in the USA will fit, and there are no known aftermarket crossover parts available, so this is the only filter that will work (save for parts ordered from overseas).

As an aside, it is not a dual-stage filter like the one I removed from the engine. This means I will need to change it more often than the dual-stage interval of 7500 miles, but that's fine with me. The only other problem is that they cost $20 each!

Power steering revisited

2006-07-15T16:52:00.000-05:00

Due to the custom pressure hose breaking at the pump fitting (due to a hose defect), I needed to re-work the power steering system a bit. The complicated pressure hose routing described earlier was eliminated in favor of a much simpler design. Instead of running to a hardline connected to the steering sector, the hose now runs directly from the pump to the sector.

The connection at the pump is a stock Trooper part. This one came with my diesel engine, but it is identical to the fitting on the 4-cyl. gas engine pressure hose (except for the pin on the side of the diesel connector - this is not necessary and I considered cutting it off). The hydraulic shop cut the hardline off the fitting and brazed on a standard threaded flare connector. This creates an adaptor fitting which can be connected to the rubber pressure hose itself.

The steering sector fitting is another stock Isuzu part, this one having been cut off the old power steering return line, which ran from the reservior to the steering sector and threaded right in. The pressure and return ports are the same thread size, so the fitting was cut off from the old hose and again brazed to a standard fitting, creating an adaptor fitting at the other end.

The hose itself is a rubber pressure hose with identical fittings on each end which allow the two Isuzu adaptors to be threaded on. This way, if the hose ever fails or deteriorates, I can just have a new center section made and re-use the fittings.

The upper right photo shows (most of) the new hose. The upper left photo shows it installed, with another short section of hose added on at the sector end to account for my measuring mistake. Next time, I will be more careful and only need to buy one section of hose!

engine bay shot

2006-06-04T22:34:00.000-05:00

And here is a shot of the current state of the engine bay. Messy, but starting to come together...

air filter

2006-06-04T22:30:00.000-05:00

Not much fabrication here - the stock diesel Trooper airbox, filter etc. all bolt in without hassles. The flexible rubber intake hose fits with a little trimming. I did have to cut a small notch in the airbox cover which allowed it to rotate toward the engine a few degrees in order to fit the hose correctly.

radiator and hoses

2006-06-04T22:15:00.000-05:00

The radiator used is a unit from a 1986 diesel Trooper. The hose inlet/outlet are on opposite sides of the radiator (as compared to the radiator from the gas Trooper); the core is also thicker and the tanks are larger, it's much more robust overall. The radiator and shroud are bolt-in items, no modifications needed to mount to the chassis.

The upper radiator hose, shown above right, is also from a diesel Trooper. It required minor trimming to fit.

The lower hose (above left, shown from underneath, with the near end being the engine end) was problematic. The engine-side inlet is larger than the outlet on the radiator and is located slightly to the side of the outlet. I tried to find a hose that had the curvature I needed which also changed diameter at some point, but I was unsuccessful (not to mention annoying to the fellows at the parts counter). Additionally, the distance is too short to use any sort of universal flexible hose.
I decided to have the radiator modified and have the outlet enlarged to match the inlet tube on the engine. With this done, I found that Gates hose #22364 has a curved section that fits perfectly (after removing a 90-degree bend at one end). According to the Gates site, this hose fits a 1998-2001 Ford Ranger or Mazda B2500 pickup. I am not sure which hose it is, or which engine it fits, but these trucks are common so I don't anticipate any problems finding spares in the future.

power steering continued

2006-06-04T22:11:00.000-05:00

These photos show the pump connections and pressure line routing for the power steering system. The new bracket and hardline are visible in the photo on the right.

power steering

2006-06-04T21:48:00.000-05:00

The power steering system was completed using a custom flexible pressure hose, a fabricated bracket to hold it in place and a new hardline to connect the pressure hose to the steering sector.

The pressure hose uses the pump end that came with the engine (although this is the same fitting the gas Trooper hose uses, just not as long and full of curves) and the opposite end is the same as the gas Trooper hose as well. I believe this hose is actually a Rodeo hose which has been modified at the pump end, as the Rodeo hose pump fitting looks to be correct at first glance but is actually different in inner diameter and will not work with the Trooper pump. Thanks to Jerry Lemond for the hydraulic fabrication work and consultation on this stage of the project. As far as I can tell, the diesel and gas power steering pumps are identical save for the pulley.

The pressure hose then travels down along the side of the radiator and is secured by a bracket I fabricated. The connection is the same as the stock gas Trooper and uses the top half of the factory bracket to retain the hose. The lower half of the bracket is a piece of angle iron. The bracket attaches to the frame on top of the bracket that holds the power steering hardlines that run along the frame, below the radiator.

The new hardline was made from a length of 3/16" brake line (I believe that's the dimension - I matched the old hardline I removed from the truck) which was bent to connect the pressure hose to the sector. The fittings on the ends were taken from the old hardline and re-used. It was time-consuming to get the bends just right, as the line is fairly short and has to be pretty much perfect or the threads won't start correctly in the sector or at the pressure hose.

The 1986 diesel Trooper uses the fluid return line as the cooler and this line is looped from the reservior to the sector, running along the frame below the radiator. The gas Trooper cools the fluid using the pressure line, as the pump is on the passenger side of the engine bay and the pressure line has to run across to the opposite side anyway. I removed the old pressure line and so was left without a cooler line. I decided to install the diesel cooler line, as it was the easiest solution (it bolts right in, no modifications needed).

The reservior was connected to the pump using a length of silicone heater hose, which is oil-resistant. The return line (below the radiator, as factory for diesel Troopers) is connected to a length of transmission oil cooler line which runs from the hardline up to the reservior.

If I had to do this again, I would modify the pressure hose end to match the return line from the gas Trooper, as the gas design reservior-to-sector hose screws into the sector. This way, I would be able to eliminate the bracket and hardline I fabricated and attach the new pressure hose directly to the steering sector. This would have saved hours of work.

more clutch hydraulics

2006-06-04T21:42:00.000-05:00

Here is a photo from underneath which shows the new clutch hardline routing, new bracket and stock flex hose used to connect the slave cylinder.

Clutch linkage

2006-02-26T22:01:00.000-06:00

The diesel clutch slave cylinder is on the opposite side of the bellhousing from the gas version (the diesel is on the driver's side), so the factory hydraulic line running up and over the engine to the passenger side of the truck would not work.

The flex hose bracket was retained and modified to be used in the new installation. The bracket originally bolted to a small hat-shaped bump on the underside of the body and incorporated a small lip which caught the edge of the bump to keep the bracket from spinning on its mount. This lip was cut off to give the bracket a flat mounting side, creating a simple L-shaped piece. Two holes were drilled into it and two bolts were welded on to be used as mounting studs. Matching holes were drilled in the body on the driver's side and the bracket was simply bolted on. I had to remove the exhaust shield to do this as it was in the way - a cutting torch makes short work of this. In fact, it would be best to do this early on in the project, as the shield is no longer needed (exhaust exits on the other side of the truck now) and the shield gets in the way during transmission installation. I used spot welds as reference points to line the bracket up, as they're visible from underneath and inside the truck, and marked and drilled from the inside the driver's footwell.

The clutch hardline was removed at the damper box (small part on the driver's fender with clutch lines going in and out; also has a bleeder on top) and cut just after its 90* bend at the firewall. I did this so I could retain the stock line, as it changes diameter at the damper box and I was unable to find a matching new line. At the firewall, a new piece of hardline is joined to the old using a brass union. Metric line is not needed, SAE line is the same diameter (I believe it was 3/16") and the union and flare fittings are all SAE which were easily obtained. After the new union, the new hardline travels down the firewall and loops up and under the flex hose bracket to duplicate the stock routing. I simply used the old metric fitting on the new line to join it to the flex hose. The stock 1988 Trooper flex hose fits the diesel slave cylinder perfectly, so a new replacement part was used.

A rebuild kit for the clutch master cylinder and a thorough bleeding of the system completed the job. It works quite well - I was concerned that the master and slave cylinders might be mismatched, but the clutch operates perfectly. No grinding into gears with the engine running and engagement is good.

The diesel slave, in addition to being mounted on the driver's side of the bellhousing, also is a different casting than the gas unit. It is possible that the innards are the same and that the gas rebuild kit would work if needed. Another thought is that since the V6 Trooper of the same body style (GM 2.8l V6) shares the diesel's slave cylinder location on the driver's side of the bellhousing (if memory serves, anyway), the V6 hardware might be a direct fit for the diesel. Also, the V6 slave and the diesel slave cylinders may be the same. I guess I'll find out when mine fails. Finally, I recommend the Harbor Freight $12 double flare toolkit highly - very cheap and created leak-free flares. Just be sure to slide the fitting onto the line before flaring!

Throttle cable

2005-11-27T22:45:00.000-06:00

Below are a few shots of the completed throttle cable. The stock (gas engine) cable was much too long for the diesel, as the intake sides of the engine are different. Also, the engine-side bracket was wrong on the gas cable. The diesel engine came with about 5" of cable, cut short during removal by the wreckers no doubt. Even if it were complete, I am sure it was from a right-hand-drive vehicle and would have been much too long for the new chassis anyway.

I bought the stainless braided universal throttle cable at a local speed shop. It had an engine-side end made for a carburetor, but was otherwise well suited to the application.
The upper left photo shows all the parts together. It was about twice as long as I needed, so it was cut back to fit.

The upper right is a shot of the pedal assembly. I cut the cable receiver off and welded it back on 90* rotated from its original position to accommodate the shackle that the new throttle cable employs (originally, the cable met the pedal with an in-line rubber cylinder, which was more difficult to duplicate than it was to modify the pedal to accept the new cable end). It fits perfectly, as luck would have it.

The second row photos are of the engine-side cable retainer nuts (left) and pedal-side shackle and firewall mount (right). I added the washers to secure it in the firewall, as the hole is larger than the cable mounting nuts. The engine-side retainer fits just like the stock cable retainer, no modifications needed.

The lower left photo shows the cable wire stops I bought, along with the stock end of the gas throttle cable (diesel is identical). My good friend Tom, who has been helping me with advice and labor throughout the project (couldn't have done it without the assistance!), found these wire stops advertised on a go-kart parts site.
I wanted to duplicate the Isuzu engine-side end, also shown in the photo. It is similar to a bicycle brake cable, only taller. The go-kart wire stops employ set screws to hold them to the throttle cable's inner wire, and seemed perfect for the task. I found some locally at a small engine repair shop - 2 for 50 cents! At any rate, the wire stop on the left is shown with the Isuzu bushing from the diesel cable installed over it. The center wire stop is as purchased, and the rightmost cable end is the Isuzu part.

The lower right photo is a shot of the completed installation. I just need to free up the pedal stop bolt, on the driver's footwell, so I can adjust it properly to the shorter travel the diesel engine requires. A few days soak in penetrating oil should do it.

Throttle cable images - click to enlarge

2005-11-27T22:28:00.000-06:00

2005-11-15T21:41:00.000-06:00

A photo of the injector pump and candidates for the cutoff solenoid. Photo posted for discussion on the 4x4wire site.

Dash completed

2005-11-15T21:22:00.000-06:00

A couple of quick shots of the re-installed dashboard. The careful observer will note the (approximately) 4200 RPM redline diesel tachometer, glow indicator lamp near the defroster button (to the left of the wheel) and the warning lamp for a full sedimenter (lower left idiot light), part of the full diesel warning lamp cluster.

As always, click images for full-sized versions.

Glow plug resistor, part 2

2005-11-15T21:14:00.000-06:00

Shown here is the mounting bracket fabricated for the 'sensing resistor' for the glow system. The bracket bolts to two unused holes in the valve cover. The resistor (a metal strip with wires attached) was bent slightly to meet the bracket and the glow power bus. Note the nut used as a spacer so it doesn't short to the bracket - I forgot to check the clearance before I welded the captive nut on the underside and it was touching the bracket (too concerned about it clearing the intercooler, which it does by miles).

Glow plug resistor

2005-11-15T21:08:00.000-06:00

Shown here is the bracketry & mounting position of the 'dropping resistor' (as Isuzu calls it) for the glow system. On low power glow, current flows through this resistor before going to the plugs. I decided to mount it with plenty of clearance to facilitate the shedding of heat. It bolts to the fender using the fuse box bolt on one side and an open threaded hole beneath the hood hinge on the other side. Unfortunately, the photo doesn't clearly show the angled bits of the more complex bracket, of which I'm proud...

Fuel system complete

2005-11-15T21:03:00.000-06:00

Here are two shots of the fuel filter/water separator/primer pump mounting bracket completed, painted and installed. The glow plug relays are mounted to the top and can be seen in the second shot. Also visible is the pre-filter (at $1.99, much cheaper to replace than the main filter at $27 if something nasty comes up from the tank!) I installed. The fuel system is now complete.

Fuel filter mount, pt. 1

2005-10-16T21:25:00.000-05:00

Here are a couple of shots of the fuel filter mount bracket being fabricated. The small 'L' at the top serves as a mount for the glow plug relays. The third mount point is attached to half of the stock Isuzu bracket, not shown. I'll post a photo of the whole assembly, painted and installed, in the near future.
I relocated the filter assembly because mounting it in the stock location (the 1988 chassis has provisions to mount the filter assembly from the 1986 diesel Trooper using the factory brackets) was not possible due to interference with the 4JB1-TC intercooler and the fact that I want to keep the passenger fender free for use as a vegetable oil tank location.
The bracket locates the filter assembly forward of the brake master cylinder on the driver's side fender and allows the glow relays to hang next to the clutch hydraulic line damper box.

Mo' wiring & fuel pickup tube

2005-09-25T22:02:00.000-05:00

Above left is a photo of the warning light cluster adapter harness. The remaining photos are of the fuel pickup tube I fabricated.

As the in-tank fuel pump had to be removed (the diesel has its own pump, fuel can't really be drawn through the electric pump and running the electric would produce too much line pressure), a pick-up tube had to be made to replace it in the armature.
I decided to cut the tube and add a flare fitting, which allowed the use of a standard union and another short piece of fuel/brake line. The Harbor Freight $13 flaring kit worked perfectly well for this - just be sure you 1) get the double flaring kit and 2) install the fitting before flaring the line.
The new line was cut and slipped into a Carter sock filter (no idea about the stock application, but I assume it fits some sort of fuel pump. Picked from a catalog at the parts place. I'll post the part number if anyone is interested...), which was perfectly sized. I added a hose clamp to make sure it won't fall off the line, but it fits so snugly it's probably overkill.
There were two holes in the top plate where the wires passed through, so I welded them shut. I plan on painting it before installation.
The filter was expensive, around $20, but the rest of the parts were very cheap. I think this should do the job just fine.

Wiring

2005-09-25T21:42:00.000-05:00

Not much new here lately, as I've just been working on the wiring and it's not terribly exciting. Here is a shot of the interior - I removed the entire dashboard and HVAC system to access the harnesses. I decided, after tracing the entire engine control computer harness, to remove it entirely. It cleaned the engine bay and under-dash area up quite a bit, and none of it was needed after the gasoline engine was removed. At least these things are easy to dismantle...

An invaluable resource has been the official Electrical Troubleshooting Manual (published by Helm, Inc.) for the 1988 Trooper. Much more information than can be found anywhere else - the Haynes manual (pictured, funny enough) is a joke when it comes to wiring information.

I decided to use the 1986 diesel warning light cluster, as it has no 'check engine' lamp, no 'O2' lamp, and it features a lamp which lights up when the water separator is full.

Instead of cutting into the chassis harness, I made an adapter harness to enable a plug-and-play fit, as the diesel cluster has a different connector. I've tried to make it easy to swap the diesel parts over to another chassis in the future, just in case, and so I design accordingly.

I used the diesel harness-side connector and the connector from the gas cluster to build the harness, as well as the electrical book and some diagrams for the diesel wiring (as well as 12V test equipment, of course). See photo in the next post...

wiring diagrams

2005-09-24T16:13:00.000-05:00

On the left is the C223 glow plug wiring. 4JB1-T is on the right. Click images for larger versions. These have been posted so knowledgeable people can help me wire the glow plug system!

Fuel filler neck

2005-08-27T15:15:00.000-05:00

These photos show the diesel filler neck I purchased (originally from an '86 Trooper diesel) next to the gasoline neck from the '88. The mounting flange and holes are different, so I made up a cardboard pattern and drilled the body to match the diesel neck. The third shot is of the new set of holes, and the final shot shows the finished product. I also peeled the 'unleaded fuel only' sticker off the inside of the fuel door, which felt pretty good ...

The diesel neck has an extra port on it, which I assume is a vent, in addition to the large drainback port present on both necks. I plan to route a hose from this port to a weather-safe location and vent to atmosphere. Diesel is much less volatile than gasoline, so all the vapor recovery ports on the tank will be plugged and related systems removed. I'll detail the other fuel system modifications in a later post.

Shift levers and driveshafts

2005-08-27T15:04:00.000-05:00

Here are a couple of quick shots showing the drive shafts before and after modification. After taking measurements from the transmission crossmember, I determined that the shafts each had to be altered by 1-13/16" -- the rear had to be shortened at the transmission end, and the front had to be lengthened -- due to the transmission having moved rearward by this amount. The rear is now in and looks to fit well. I have yet to install the front shaft, but anticipate no problems.

The last photo shows the shift levers (the ones that came with the truck were re-used -- the diesel transmission lever was bent for shipping ease and destroyed, and the transfercase lever was shaped differently and interfered with the center console, so I used the US gasoline chassis levers) and their positioning. The transmission shift lever looks close to the console because it's in 2nd gear in the photo. The console clearance is tighter than it was, but everything fits and feels fine after sitting in the driver's seat and running through the gears. The gas transmission lever had a slightly different end than the diesel version, as there was a guide 'bump' on it not present on the diesel lever. The diesel shift tower has the channel to accommodate this, however, and it seems to work fine, so I am not sure why the difference between them.

Navigational Aid

2005-08-25T13:03:00.000-05:00

Photos can be viewed full-size by clicking on them, and older posts can be accessed by using the monthly links on the right (under 'archive'). Thanks for the interest.

Transmission mounting

2005-08-22T22:06:00.000-05:00

As usual, click images for larger versions.

The drivetrain is in except for the driveshafts, which have been modified and are ready to be reinstalled.

The top shot is of the transmission crossmember. It is symmetrical about the long axis with the exception of the extra set of mount holes drilled in an extended area shown at the lower edge in the photo. These are the mount holes needed to mount the diesel transmission, as mounting the engine using the stock diesel mounts places it about 1-13/16" rearward of where the gas transmission was.

The crossmember needs to be rotated 180* and reinstalled to use these extra holes. There are driveshaft cutouts on both sides of the crossmember, as well as bolt holes for the bash guard (although they aren't tapped on the unused side, so I'll have to figure something out - large sheetmetal screws?) , so it's obvious Isuzu meant for it to be flipped around depending on application. This is the key to a bolt-in installation.

Second shot is of the three jacks it took us to get the transmission installed (black jack under bellhousing is barely visible). The diesel bellhousing has got the starter motor 'bump' on the opposite side as compared to the gas unit, so simply lifting the transmission up and in results in the bump hitting the body of the truck before it can mate properly with the engine.
The procedure to get it installed correctly requires the transmission be rotated as it is raised. We accomplished this by using three floor jacks, two large (3-ton) and one small. The large jacks were positioned under the bellhousing and tailshaft, while the small one was under the transfer case to be used as a rotational aid. I still had to lay underneath and bench press the bellhousing to help it rotate and to check alignments.
The transmission should be rotated about 90* clockwise (looking at the flywheel side of the engine, which is where you'll be when doing this!) so the starter bump is up in the tunnel of the body. Get it as close as possible, then rotate the transmission back until it's about 45* past its normal mating position to get it the rest of the way in, rotating it back to the correct location as it's shoved onto the clutch assembly. This process is a pain, but it won't go on without rotating as it interferes with the body.
I also pounded the exhaust shield back to allow for more clearance. Another trick we employed was to use a long 2x4 board to lift the transmission up before sliding the jacks under it (one end of the board stuck out on either side of the truck, so 2 people could grab the ends and lift the transmission up).

Final shot is of the diesel transmission sitting on the (rotated) crossmember, using the stock mount.

Transmission

2005-08-10T00:47:00.000-05:00

Attached are shots of the two transmissions. The gas unit is the dirty one. They are identical from the rear of the bellhousing back. The clutch release and starter are on opposite sides, which means that the diesel bellhousing is needed (at least) to use the 4JB1-TC engine.

Crossmember bolt blues

2005-08-10T00:00:00.000-05:00

Remember the frame crossmember bolts? I had broken three of them off in the frame while trying to remove them. There are four on each side, and while one side had four good ones, the other had only one.

Drilling resulted in a bit being broken off in one stump, and an extractor being broken off in another. Welding nuts onto the remains proved futile in getting them out. What to do?

I hadn't noticed, but there are 2 holes in the frame situated between the crossmember bolt holes. Drains? I don't know, but I decided to put them to use. I drilled the crossmember so it had holes to match, and bought some grade 8 hardware to attach it with. After tapping the frame holes, cutting the bolts with a die, and adding my new holes, the crossmember will be as sturdy as it ever was. I think if I had broken all 8 bolts off, drilling 4 new holes and using only 2 bolts on each side would hold it without hassles. These bolts are pretty tough.

I did end up drilling the opposite side of the crossmember, as I planned on reinstalling it 180 degrees rotated from its original position. Why? Read on...

Attached is photo of the new holes to give a better idea of what I'm talking about.

Engine is in!

2005-08-09T23:17:00.000-05:00

Been a while since the last update... much has happened. The engine is in -- after much deliberation as to whether or not to build custom mounts, it was decided to try the mounts it came with. Glad I did.

After some measuring, it was determined that while the 4JB1-TC mount pads would bolt directly to the frame, it would place the rear edge of the block about 2" rearward of where the rear edge of the gas block was originally (as measured from the mount pads on both engines). This would then shift the transmission rearward by the same amount, which I thought was a bad idea as it would cause the rear crossmember transmission mount not to line up.

I considered building custom engine brackets to get the engine forward about 2", but this would necessitate the use of an electric radiator fan, as the mechanical fan would be too far forward. At this point, I heard from the Isuzu guru himself, Mr. Lemond, that the crossmember had an extra set of mount holes that may accomodate the rearward mounting of the transmission (I hadn't seen these, as my crossmember was still attached to the old transmission - one of the mount bolts needed to be torched off. Had this done promptly after hearing of the extra holes...). Things are getting interesting...

We then decided to try mounting the engine in the truck using the mounts it came with, which resulted in what seemed to be perfect placement of the engine. The mechanical fan looked like it would clear the radiator, and it sat in the bay just like stock. Even the heater hoses line up! Time to try our luck with the transmission.

Here are a couple of shots of the engine sitting in the bay. Click the images for a large version (this applies to all images on the site, by the way).

Intercooler + scoop

2005-07-14T22:02:00.000-05:00

The engine I've purchased came with the top-mount intercooler - a pleasant surprise, as it means (slightly?) more power. The only trouble is that I've now got to find a way to get fresh air to it in order to make it work as designed.

I've got a couple of options: I could either convert to a front-mount intercooler (like the Dodge Neon SRT-4 and Mitsubishi Lancer Evolution have visible through the front bumper) or incorporate a hood scoop like the Trooper in other markets uses. No problem, right? Hood scoops are sold by loads of performance vendors. The trouble is that aftermarket scoops like those available from JC Whitney would either look terrible or require a lot of fabrication in order to work - or both.

I've learned that the factory Isuzu Trooper hood scoop used on the intercooled diesel models is a bolt-on item. I've even found a fellow in Australia who is willing to help me import one, along with the necessary gaskets and hardware. All I need to do is cut a hole in the hood (or so I've been told).

EDIT: Attached is a photo I found (just so there's no confusion) of a Trooper with a factory scoop. Doesn't look too bad, no?

A few more links

2005-07-14T21:49:00.000-05:00

Nothing new to report, but here are a few miscellaneous links:

The wir e.

General Trooper FAQ

4JB1-T performance
(The forum link above has got a lot of information on the engine I'm using, as these engines were sold in New Zealand and Australia. There are other performance threads as well. Here is the main forum index.)

Another Isuzu forum from down under.

A quick link

2005-07-12T20:24:00.000-05:00

Here is the thread where it all started. In case anyone is unaware, 4x4wire is an excellent resource for Isuzu technical information. I'll be posting in the thread as well as on this site, mainly to try and get some answers as problems crop up. I'm sure there will be a few.

Engine removed

2005-07-11T23:31:00.000-05:00

After removing the transmission, radiator, fan and much unnecessary underhood clutter, the engine was easy to finally pull out.

Engine support

2005-07-11T22:22:00.000-05:00

As the engine is mounted at the front only, its rear is supported by the transmission. After the transmission is removed, there is no rear engine support and something has to be rigged to keep it from tilting backward. As we needed to move the truck out of the garage to pull the engine (low ceiling), I couldn't support it from underneath using a jack. Instead, we came up with this nifty, free hanger using a piece of fencepost and some chain. Radiator hose was used to keep it from scratching the fenders. I liked it so much, I think I'll use it again on the diesel when it goes back in.

Magic and more magic

2005-07-10T21:51:00.000-05:00

The old drivetrain is out. It took a bit of doing, and some mistakes were made, but the Troop is ready for the new engine. The process (after first soaking every bolt I could find in PB B'laster for a couple of days - best penetrating oil I've found):

The transmission has to be removed first, from underneath obviously, requiring the removal of the driveshafts and frame crossmember. Getting the driveshafts out without air tools was a small challenge - the trick is to wedge a pry bar in the U-joint and against something else (floor, frame, leaf spring, etc.) to keep the shaft from turning while the bolts are removed. A socket can be used on the bolt heads, but it won't fit quite straight. Try turning the shaft and finding the best position to fit the socket.

The rear shaft is supported in the middle by a carrier bearing, which can be detached by removing two bolts. The rear shaft can then be slid rearward, out of the slip yoke at the transmission output, and then the whole shaft can be removed from the truck by sliding it forward until it clears the carrier bearing bracket. Just don't get it tangled on the emergency brake cables ...

The frame crossmember was a tough one. The truck had seen farm duty, and the frame was packed solid with dirt and gravel. This had, in turn, trapped water above the crossmember bolts and caused much corrosion. The bolt tops are accessible through holes in the frame (once the dirt is removed) and I oiled them liberally for a few days. Still, the first two I tried to remove broke off in the frame. At least the crossmember would be free, even if all of them broke, but the drilling required afterward was unappealing, so a bit of heat was applied.

First try heating a bolt using a MAPP torch (not quite oxy-acetelene, but it will cut steel) yielded the same broken bolt. Now 3 of 8 were broken off. We decided to try more heat. Starting with propane (the Magic) - to save money on MAPP and oxygen tanks - and then switching to the MAPP torch (more Magic), we got the bolts to glow a dull red and that was enough to get them out without damage. Heat is your friend in cases like this. Still have to drill 3 of them out, though. More later ...

Background II

2005-07-09T14:21:00.000-05:00

Why the project? Several reasons. The overall goal is to reduce my comsumption of imported oil. Diesel vehicles offer an advantage in that they are able to burn bio-diesel fuel without modification and straight vegetable oil (SVO) with some fuel system changes. I intend to add an SVO system to the truck after the engine installation is complete. Either way, these fuels are made from domestically grown crops, are renewable and are carbon-neutral - or about as close as you can get - meaning that they do not increase the amount of CO2 in the atmosphere when burned (as the plant source of the fuel captured CO2 as it grew, and burning simply re-releases this into the atmosphere to be captured again by other plants). Petroleum fuels do not offer these advantages.

There are a number of reasons to be concerned about these issues. Please read up on peak oil, global warming and mid-east geopolitics if you'd like an idea as to where I'm coming from. It's all interrelated. Here are a few items to get you started:

For a look at peak oil, try this excerpt (the book it is taken from is an interesting read, as well).

For information on biofuels, try these sites: www.journeytoforever.org and http://forums.biodieselnow.com/default.asp.

Some thoughts on the politics of oil, specifically relating to Iran, can be found here.

So, with a goal identified, why choose this particular vehicle? Why not buy a Volkswagen TDI or an older Trooper with a factory diesel engine (available in the US in 1986-87)?

I've owned an '88 Trooper since 2003, when I bought it as a winter vehicle. I've come to love its versatility, low maintanence and economy. It's got a 2.6 liter gasoline 4-cylinder and a 5-speed gearbox, which gets around 20 MPG - not bad for something its size. The high roof and folding rear seat offers massive cargo capacity and the 4-wheel-drive is perfect for the nasty MN winter weather. Finally, these vehicles don't command very high prices on the used market and parts are easy to find and cheap.

Unfortunately, road salt had taken its toll on the truck and it was time to replace it. With a diesel vehicle in mind, my options were limited. I wanted a diesel Trooper, but they're rare and costly. Good examples go for more than $4000 on eBay, and I couldn't justify the price, especially considering the reputation these trucks have for being underpowered. Parts availability for the 2.2 liter turbo diesel engine is spotty as well, so I decided to look elsewhere. Newer VW diesels were too expensive and hard to find used, older VW diesels weren't for me (slow, spartan and rare around here) and new diesel SUVs were rediculously expensive (Jeep Liberty at well over $20k and the VW Touareg at $50k+).

Instead, I purchased a 1982 Mercedes-Benz 300D sedan last winter. While it was in decent shape, it was nearly worthless in snow or on ice and parts were often mail-order-only items. Certain systems tended to break often, such as the automatic climate control and the transmission shifting controls, making it a pain to own. I sold it after a couple of months and set out to find a more suitable replacement.

I knew that better Isuzu diesels were offered in the Trooper in other countries. Not much information was available, though, so I made heavy use of Google and online forums and was able to get in touch with people who had converted Isuzu vehicles or owned them in other countries. It was starting to seem likely that the 4JB1-TC would be a direct bolt-in engine for the 1988-1991 Trooper chassis (4-cylinder trucks, anyway). I even found an importer who could get me the drivetrain. All I needed was a donor truck.

As the 4-cylinder gas engines have a reputation for being very sensitive to overheating, leading to damaged cylinder heads and other problems, I set out to find a Trooper with a good body and blown engine to use for the project. I found one about an hour away from me. It had overheated and ruined the engine, was partially disassembled and had an excellent body and interior. For only $200, it was mine. I ordered the diesel engine, and the project was underway.

Background

2005-07-08T14:21:00.000-05:00

This site is intended to document the process of converting a 1988 Isuzu Trooper to diesel power.
The engine used is the Isuzu 4JB1-TC, a 2.8 liter direct-injection intercooled turbo diesel, which was available in this chassis outside the United States.

Since I'm located in the Twin Cities (St. Paul, MN, USA to be more precise) I had to import the drivetrain from Japan. I received a complete engine and transmission through an importer in Florida for a good price. It's claimed that the engine/transmission have around 45k miles on them, and judging by the appearance of the parts, I'm inclined to believe it.

Here is a photo of the donor chassis, before any work was performed.