1988 Isuzu Trooper diesel conversion

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?

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

The wire.

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.

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.

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

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.

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 ...

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.

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.