1988 Isuzu Trooper diesel conversion

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!