’02 Isuzu Axiom 3.5 L Engine Swap in Isuzu Trooper

A customer came in to my weekend job with a 1998 Isuzu Trooper that had locked up the original 3.2 liter engine. Being that this customer uses this Trooper to go off-roading he wanted to use this as an opportunity to upgrade.

Rather than reinstall a 3.2 liter engine, he decided he wanted to go to a 3.5 liter engine out of an Isuzu Axiom. This required a couple modifications, the main on being the removal of a plug in the head to install sensor the Axiom engine didn’t have.

In some cases what you could have done was drilled in, and ran a tap into the plug, then find a bolt to thread in tightly, and use a slide hammer to pop the plug out. I went the difficult route and drilled it until it popped loose.

After drilling out the plug, I was able to simply clean up my shavings and install the sensor from the original engine.

I also had to swap over the knock sensor which was straight forward. Both the Isuzu blocks and heads are essentially cast the same. So the threads and holes needed to install these sensors are there, they’re just unused or plugged.

top left closest to the screen, and center right next to the chain. Two sensors that have to be installed.

The knock sensor just threads straight into the block no drilling or tapping required. Due to this I was able to swap the knock sensor in and have it threaded in a matter of minutes.

This engine swap also required me to swap over the wiring harness, intake manifold, injectors, coils, all accessories, the clutch kit, and water neck. Before putting the used engine in, we decided it would be a good idea to also fix any wiring faults, and install new timing components, and spark plugs.

After repairing the harnesses I turned my attention to installing the new spark plugs. When removing the old spark plugs I saw that a couple were covered in oil on the top side of the plug. This is an indicator that you have a leaking valve cover tube seal.

So as described in the video, anytime you see oil on your plugs you want to make sure you get these tube seals replaced. They are included with your valve cover gasket set. They typically just pull straight off from the tube, and the new seals slide right on. Take note that there is an inner lip, and you want the tube seal all the way flush to this lip. This ensures a proper seal. I looked into this specific engine model, and found guys were running their plug gap between .036 or .040. I opted to go smack dab in the middle.

Next up I swapped over the exedy clutch kit he had installed on the previous engine. This junkyard engine he brought us came out of an automatic. So I needed to remove and replace the flex plate with my flywheel from the engine that came out.

Whatever you do don’t forget the pilot bearing. With all honesty, I actually did forget to install the bearing the first time around. I used the age old trick of packing the inside of the bearing with grease, and then forcing more and more grease in until it forces the bearing out wthout damaging it. Then when reinstalling you simply tap it in as straight as possible.

Next up make sure you have your clutch disc centering tool, and install the clutch disc making sure you put the flywheel side toward the engine. You then will put the pressure plate on over the clutch disc. I always make sure to put locktite on all of these bolts, flywheel, and pressure plate. This ensures these bolts stay tight when tightened.

Next up was swapping over all the accessories. This was more a precaution than anything. we knew these accessories were good, and worked with the wiring harness we were using. Rather than taking a chance with using any of the accessories that may be bad, or not cooperate with the harness we are using. I ended up having to swap over the bracketry as well. All of this took some time to get figured out due to slightly different designs.

Unfortunately I was waiting on parts so I didn’t get the luxury of replacing my intake manifold gaskets, and valve cover gaskets before dropping the engine in. So I was forced to do that in the car. However at this point I have now completed the oil change, and we will be replacing all the exhaust gaskets as well. I’m hoping the customer enjoys the little bit more low end torque he has.

Leave a Reply