CLAYTO™'s 4JG2 to 4JJ1 conversion/resto

[claypot75]

As some may already know, my Jackaroo was running a 3.1 4jg2 turbo diesel intercooled engine. It had about 420,000km on it and was starting to get a bit tired. And even after spending quite a few dollars on it to keep it running and even extract some more ponies, it just wasnt cutting the mustard. Knowing this, i had been planning the ultimate diesel swap for the mighty jack for quite some time before taking the plunge and seriously searching for a replacement donk.

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The donk in question is the Isuzu 4jj1 3.0 turbo intercooled common rail engine used primarily in Isuzu Dmax's and Holden Rodeo/Colorados from 2007 to 2012 (although it is still being used in current Isuzu Dmaxs and MUX's)

Finding a stand alone engine wasnt proving to be very successsful, so i decided to have a look at the salvage auctions for a wrecked Dmax. After a few months of searching, i got lucky and found one that was suitable, and was lucky enough to win the auction at a price that was well below my budget.

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So, first job was to strip down the Dmax, this was interesting, as I had to be really careful with all the wiring harnesses in order to be able to re use them at a later date.

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[claypot75]

Once the dash was out, it was time to take the cab off

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Next job was to remove the old 3.1 engine and gearbox from the Jackaroo.

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This is where things got interesting, as it uncovered years of wear and tear, as well as some pretty average repairs by previous owners. We found more cracks in the front chassis crossmember that we'd previously missed. So, time to break out the angle grinder and mig and sort it all out.

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[claypot75]

At this stage, I also determined that the engine bay was in need of some lovin too. Turns out the second battery had been leaking acid onto the guard below. So, time to respray the engine bay!

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[claypot75]

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First time out with a paint gun, I thought I did an OK job.

So, you probably noticed the steering and front diff were missing in these last few pics. Well this was for a number of reasons. Firstly the front diff was making some unsavoury noises, so investigation was needed. What better time to do it that when the rest of the car is in bits.

Anyways, dropped the oil, and as suspected, nasty metallic grey diff oil came out. Hmmm, not cool I thought, because not only was there 4.55 gears in there, but also and ARB Air Locker. So I stripped it all down and found that the air locker casing bolts had undone themselves and had been grinding on other parts of the diff.

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Once stripped down, everything was cleaned and new bearings and seals and some new casing bolts were installed, along with the 4.3:1 diff gears.

Why 4.3 diff gears I hear you ask?
Well, the dmax engine is very torquey and in stock form they run either 3.77:1 in the manual and 4.1:1 in the auto. So using my profound logic, I decided that 4.3's would be well suited to my application.

Once the diff was sorted, it was time to give the steering the once over, as it had been pulling to the left, yet the steering wheel had to be pulled tot he right. Thinking it was only the drag link being worn out (inspected previously and found the ball joint boot was cracked and dry inside), yet i also found the idler pivot was bent due to some monkey using it as a leverage point. So these two items were replaced with new items.

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[claypot75]

Next job was to start re assembling the diff and steering. Whilst doing this I found the right hand upper control arm appeared to be bent, probably another reason for it wayward steering, so, of i went to the wreckers and got me some new (second hand) upper arms. Before installing, i decided that they had to be at least 13 years old, so the best thing to do would be to replace the upper arm bushes. Not the most funnest job to do, but hopefully the last time I'll have to do it!

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Next on the ever growing list of stuff to do, was the cv's. Now the old ones had been making the dreaded clicking sounds for at least three years (even had the inners installed back to front for one trip, sounded like a bloody excavator!), and had no right being in the vehicle, especially without destroying themselves. So while the diff was still out, I replaced the cups and inner axles with a set of the best second hand ones i could find (low mileage units with very little to no wear), along with some new bearings and seals. I also sourced a good set of cv's from cup to stub, re booted them with fresh grease and some really good boots with nice thick rubber.

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Next job on the list was to re install the kuckles, hubs and brake calipers. These all went back together nice and easy (all things considered), until I went to put the brake calipers back on. This got a little curly, due to the fact that I had swapped out the Jackaroo calipers with the larger twin piston Dmax calipers. First issue was that the caliper would touch the hub once done up tight, not ideal, so after a bit of fiddling around, decided to give the dmax hub and disc a go, which worked a treat once I had trimmed and replaced the dust shields with the dmax ones as well. Next up was the brake line, the Jackaroo ones were now too short. So, what does one do, they go all special and have a full set of stainless braided brake lines made up (damn expensive too might I add!).

Once all those bits were buttoned up, I could put the wheels back on. Was feeling a lot better about things after that, because seeing your pride and joy stripped back to the bone isn't a nice feeling!

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[claypot75]

While all of this was going on, loads of research and preparations were being made in readiness for the new engine install.

Whilst researching, I found that the manual transmission from the Dmax wasn't going to be suitable for this application. A number of reasons, but the long and short of it was that I would have to do a body lift in order to install it, and the transfer case was a fully electrically actuated, chain driven unit, which I have had experience with in the past on another vehicle, and decided that I definitely didn't want any part of that. So, after realising that the stock 3.1 manual transmission was likley not going to be up to the task of taking the masses of torque from the 4jj1, I decided that my best option would be the auto trans from a dmax.

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This had a number of advantages in that it is the same type of auto used in the 4jx1 Jackaroos. What this meant was that I could use the Jackaroo 4jx1 auto trans transfer case and adapter, both propshafts, trans crossmember, and weld to the chassis a pair of 4jx1 crossmember mounts.

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What all of this meant though, was that the looms and computers that I had kept aside from the donor Dmax were now virtually useless to me as they run a different loom and ecu between manual and auto (and in turn a differently coded security set). So, on the phone to a bunch of wreckers, to eventually find all that was required from one place (ideal), hand over the credit card, my left arm, and half my right arm, and next minute, all my magic wiring loom and witch doctor black boxes arrived!

While this was going on, I installed all the engine bay gear such as the brake booster and master cylinder, brake lines, wiper motor, and anything else I had pulled in order to paint the engine bay.

With that, I set about changing the engine loom before dropping the engine into the Jack using a fresh pair of engine mounts. Fortunately for me, the 4jj1 and 4jg2 use much the same block, and in turn allowed me to use a combination of factory adapter plates and engine mounts from both engines for a no weld engine swap.

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Next job was to install the engine bay wiring loom, fuse box, ecu, and a few other bits and pieces.

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[claypot75]

Once the engine and loom were in place, it was time to turn my attention to the transmission, and get that installed. Overall it was straight forward, as I had previously had them both mated up on the old dmax chassis, and everything went well there. Yet when it came time to put it all together, we just couldn't get the box to mate up with the engine. In the end we found that the supplied dmax torque converter was bent on the front pin (noting that I hadnt put the TC in when doing the test fit on the dmax chassis). I had a spare 4jx1 torque converter from a parts gearbox, so we installed that and everything slid together no problems.

On to the interior, again, in the background, I had been removing the Jackaroo dash unit in preparation for the wiring loom to be installed. This part wasn't overly difficult, basically it was a case of remove the dash unit, replace the old loom with the new, and re install. But before reinstalling the dash unit, the new body loom was installed, which meant that all the HVAC had to be removed, along with the steering column. Heres where all the fun mixing and matching really began!

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As the dmax motor is somewhat wider on the top half (being twin cam 16 valve n all), it meant that I was unable to use the diesel Jackaroo heater core as its ports point stright through the firewall and into the intake manifold. This wasnt going to work, so, havin wrecked a few Jackaroos over the years, it was out to the parts bin to find a v6 heater core with the right angle outlets that go through the firewall. Super, worked a treat!

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Next was to replace the old steering column with a late model one. My reasoning for this was so that I could use the column mounted indicator/headlight switch, and wiper switches which were mounted up on the dash facia on the early gen2 Jackaroos. This would also blend in better with the wiring loom for the dmax.

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Once all the looms and hvac were buttoned down, I reinstalled the dash unit.

This is where all the fun starts with integrating the Dmax wiring loom and Jackaroo switchgear. Now, I'm no sparky, and wiring is definitely not one of my strong points, but, I can read and kinda learn stuff. So, time to hit the books!

I got myself a set of factory workshop manuals for early gen2 jacks, post 98 jacks, and for the dmax. Read up on all the different wiring systems, and hooked into mating everything up, one system at a time, going through all the basic hookup items like security control boxes and the like, to hooking up indicators, lighting, wipers, hvac, windows, mirrors, everything! I had a mate of mine who is right into electronics and whatnot come in and do all the soldering (he saw me doing it, and basically said, that it would be better if he did it).

While all this was going on, I installed the new instrument cluster. This was sourced from a top of the line Holden Colorado of the same vintage as the Dmax (they were basically the same vehicle).

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Once all of the major electrical connections were made we were good for a start. However, I hadnt attended to the fuel situation yet. Next job, install fuel lift pump. Now, in the diesel Jackaroos, there was never any in tack fuel pump, yet in the Dmax there was (much like a petrol Jackaroo), to the easiest way around this was to install an external fuel pump. Once this was done, battery temporarily installed, we could prime the fuel lines, and go for a start.

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[claypot75]

Another job I had been doing in between the others was installing the new (second hand) rear diff.

Previously I had installed the widetrack front suspension, but not the rear diff, due to the gearing not being available for the rear. Since rebuilding the front diff and regearing to 4.3:1, this enabled me to use the widetrack rear diff as it was also geared with 4.3 gears.

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Whist installing the rear diff, i used the heavier duty late model trailing arms and panhard rod, installed the rest of the braided brake lines, and made up a new extended diff breather.

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So while i was messing around with diff breathers, I installed the DANTECH™ remote diff breather block, ready to accept all the breather lines.

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Nearly there

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[claypot75]

Over the weekend old mate Sammy and I put together most of the brackets for all the gear in the engine bay. Still got the battery tray, power steering res and washer bottle tank to go.

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[claypot75]

Installed new custom battery tray, washer bottle, power steer res., and headlights n grill

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Also installed the instrument cluster and fuse block

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And thats where I'm at right now. More to follow over the next week or two. Feel free to ask questions etc

[geeves]

thats a biiiiiig project

[claypot75]

Oh I know, its been a fun filled 6 months!!

[turnturn]

Well done Claypot....I hope the rest of the build goes OK for you.

[isuzurob]

You have done a great job. i have a 4jj1 for my swb 89 bighorn, im going to run the dmax g-box and old bighorn transfer case, or try the 2.8 box, also have been talking to link to see if they can make an aftermarket computer to run it, so no need for egr, immobilizer, airflow meter, and more power, which will make wiring far easier, you have helped me with ideas already with your build

[claypot75]

Thanks for the kind words boys.

And feel free to hit me up for some ideas if you need them isuzurob

[MUVIT]

well done

[stardog]

Massive job and time plus $$$ put into it you must love that jackaroo for all the work you have done on it but it will be one of a kind.
Very impressed with your work you have done and a wonderful write up and the photos amazing job clayto.
stardog

[claypot75]

Thanks again guys

Probably should give a little bit of background info on the Jackaroo.

Dad bought it new in '92, kept it for four years and sold it in '96 to an older gentleman, who in turn kept it for another 14 years. He traded it in as he was getting a bit old to use it and look after it. At this stage the car disappeared for about 6 months, and popped up on ebay, coincidentally at the time I was looking for a Jackaroo. I noticed it, and it looked very familiar, so dad n I went and looked at it, and yes, it was the old family bus (even the owners manual was the original with dads name in it and all). So that was it, I had to buy it, and as they say the rest is history.

Since then i've done all the suspension and all the extra bits n pieces one would expect for a decent touring/very capable rig. The Jackaroo has been featured in 4wd Action magazine 4 times, and pictures of it are regularly used in that mag.

Heres some screen shots of the feature writeup they did:

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[geeves]

one question
The lower control arms. What year did they become stronger? Is it a case of straight to the ubs73?
Both were bent on my 94 bighorn when I bought it. I havnt bent them again but they are a known weak point and I cant really afford 800 for the indy4x4 ones

[claypot75]

Rear lower trailing arms im guessing is what you are referring to.

Ive only looked on late ubs73's, the set i got were off an 02 model. They are about 4 or 5 mm larger diameter from memory. Direct bolt on too.

The indy4x ones would be nice. But yeah, bulk $. And they dont do an adjustable panhard rod either, which you would kinda expect for that kinda money