1987Comanche

I started the autopsy on my old 4.0 tonight (will post other pics in the MJ project section tomorrow) but I found this and wanted to post it. WTF happened to the piston ring groove on #1???? The spot shown in the photo is roughly 2X the width of the rest of the PR groove

Almost fully assembled... She runs!!!! Out on her maiden voyage (note lack of front bumper and the fact that the wiring is zip tied off the ground) She was running poorly and, subsequent troubleshooting uncovered a bad fuel pressure regulator, vacuum leak, and exhaust leak. She runs great now :MJ 1: I still have a leaky rear main to deal with (one of the 3 seals I didn't install myself...thanks ATK :fs1: ) but I have almost 100 miles on the new motor :banana:

Finally got her running well :banana: I found an exhaust leak (welded it shut), a vacuum leak (made a new harness), discovered the fuel pressure regulator was shot (dumping tons of gas into the intake via the vacuum harness), and threw on a new fuel filter for good measure. She runs!!!! :MJ 1:

Yep, sanded the dipstick and block in that area and reattached 4 ground wires (3 small, 1 large). Also sanded the Driver's rear head bolt and attached the braided ground strap. I checked TPS voltage and it was nearly perfect (0.82V). I looked at all the vacuum lines and didn't see any obvious issues. I did find that my catalytic converter has apparently split at the seam on the driver's side (aftermarket replacement by PO). Could this be the source of my issues? It seemed quiet before the motor swap but bear in mind my manifold was almost 100% cracked around cyl 5 and the rear stud was broken off in the head (no retention of manifold by cyl #6).

I finished wiring everything up and got my new 4.0 to run!! It was, however, not without some drama. I ended up having to crank it a total of 8 or 9 times over the course of the day while troubleshooting/replacing various components. The wiring on the CPS was loose (hit the firewall during engine install?) so I replaced that and it still wouldn't fire. I pulled plugs 3 & 4 and they were gas soaked so I knew the problem was spark. I swapped out the distributor with my old one and then verified timing. It turns out the dizzy was 180 degrees out. When she first fired up I only let it run for 10 sec as it sounded really rough (popping, etc). After giving it some thought I put the new distributor back in, verified timing, and tried it again. This time she ran well enough that I was able to bring the engine to 2000 RPM and held it for 15 min to break in the cam (as per rebuilder's recommendations). I changed the oil, added more ZDDP (again as per rebuilder's recommendation), and checked her at idle. The idle is pretty rough (fluctating between 650 and 950 RPM). I'm planning to check TPS voltage and make sure all the vacuum lines are connected. What am I missing??

New engine is in!! Trans conversion to external slave is complete: Flywheel, dust shield, pilot bearing New engine and trans with external slave conversion, ready to go in! Engine is in

Engine & trans are out!!! The trans mount was dripping rubber! The oil leak had turned it into Jello

Engine should be ready to come out this weekend...

Started prepping the patient for her heart transplant last night:

Tonight I discovered the crank in my reman engine was apparently originally in an AW4 equipped vehicle. The Renix AX-15 crank apparently used a .945" OD and .591" ID bearing: http://www.napaonlin...5446_0072572747 I'm converting the trans to an external slave and have a clutch kit for a '96 XJ. Pilot bearing OD is 1". http://www.napaonlin...B128_0072575625 I knew the ID would be off but I wanted to check the OD. The engine is on the stand so I can't get calipers to the back of the crank. In theory there's no way the 1" OD bearing would fit. It dropped in and didn't make contact with the ID of the crank at all. This leads me to conclude that the crank was originally hooked to an AW-4. NAPA lists a pilot bearing for an AW-4, even though that doesn't make a whole lot of sense (why would an auto have a pilot bearing?) http://www.napaonlin...B657_0072572740 OD is 1.1", ID is .590" So I'm assuming I need to use the pilot bearing they list for the AW-4? ID is 0.001" off and the contact length is greater. Will either of these make a difference? Has anyone else run into this?

That's what I thought too :D . Got the reman dizzy in tonight and set the timing. Ended up having to hand sand the distributor body to make it fit b/c it was shot blasted during reman. That screwed up the OD in relation to the reamed hole in the block. :doh:

The Renix CPS is a direct plug and play for a later model HO AX-15 bellhousing, correct? No weird spacing changes, etc?

Put the balancer on, filled her with oil, and primed the new engine last night. 72 PSI oil pressure on the stand!!! :banana: I don't think the gauge in my truck has ever seen anything above 40psi.

The new engine is almost done!!! I have to pick up a balancer tomorrow, then it's time to add oil, chuck the drill to the gutted distributor, and prime the new motor while checking oil pressure.

Bored 0.030" over but other than that bone stock. Right now the plan is to finish putting it together and transplant her. I did, however, run into a snag. I was checking everything out with a borescope and found a big chunk of something (cooling system sealer? Grease and sand?) in the water jacket. I had to pull freeze plug #2 to get it out. Everything else seems ok so far.

Maura's new heart arrived this week. I'm currently collecting parts for the transplant...

Drive heel, coast toe pattern. Is the carrier centered in the housing? What's the pinion runout on the yoke mating surface? Those are the 2 areas I'd check.

Tore the donor engine down (from the other '90 MJ) and it turns out the motor is fried. Cam bearings are gone, journal bearings are gone, crank is scored, valve guides are worn out, and last but not least there's a huge (0.030") ridge on the top of cyl #1 and 6. Add to this the crack in the top pass side bell housing bolt and this engine is in rough shape. I spoke with the machine shop and they said I'd be better off looking for another engine.

If only I had taken a head on shot :(... in my defense it was in the front row at a mall. Taking a shot of the front would have required standing in an entry/exit lane. It's in WNC (Asheville). If anyone is in that area keep your eyes open...

Just got back from a business trip and found 2 MJ's on the way. I was originally going to post the '89 in the classifieds section but then I found the Comanche Chief. '89 Pioneer, 2WD, LWB, 5 speed.130K Comanche Chief (1987??), SWB, 5 speed, 4WD, 283K miles!

I haven't updated this thread in quite some time but there has been a big development. My MJ's motor is very, very tired and as of late she's been moved to the semi-retired list. I have tons of blowby, a very healthy oil leak, worn valve guides (almost constant smoke from the tailpipe), and rod knock. She'll run but is consuming & leaking about 1 qt of oil every 150 miles :eek: . I'm helping a friend rehabilitate his '90 MJ and we pulled a donor engine for him @ the jy a few months ago. He rebuilt it and we pulled his drivetrain this weekend. The motor from his '90 will be rebuilt and find a new home under the hood of my '90.

I've been keeping the trans topped off with 10W-30 and it looses 1/2-3/4 quart every 3K miles. Other than going into 3rd the trans seems to behave ok. The slave seems ok but I will say the clutch is oil soaked. If I didn't have to pull the motor I'd leave it alone but since it will come along for the ride on the cherry picker it would be the perfect time to investigate. Is there a way to inspect the innards of the AX-15 without separting the front case from the intermediate plate? Based on the 2WD AX-15 I autopsied I'd say no but that was the first one I ever pulled apart. I'd hate to pull the trans 10k after pulling the motor but, if an investigation isn't warranted then I'll be happy to hook the new motor to it and drop the whole thing back in.

As the title says the AX-15 on my '90 apparently had/has one heck of a leak. I pulled the drain plug and about 2 oz of oil and goo came out. I refilled it and have been monitoring the oil level. It seems ok (not noisy) but is a bit "notchy" and can be harder to shift into 3rd at times. I'm looking at pulling the drivetrain out when I swap the motor (worn out 4.0 out, better 4.0 in) and wondered what to do with the trans. There's no bearing whine per se but running completely empty for an indetermined amount of time is worrisome to say the least. Thoughts?

2WD output shaft is a lot longer and has provisions for a speedo gear on it. I have a completely disassembled 2WD AX-15 in the basement and I tore it down to see what was interchangeable. The front 3 parts of the tranny (case, intermediate plate, and bellhousing) are identical and the 2WD extension and 4WD adapter plate can be swapped. You can swap a 4WD output shaft in place of the 2WD but it involves pressing everything off the output shaft (basically a rebuild).

I'd look at the fuel pump next. It sounds like the pump overheats and is shutting down on you. Can you make it buck, surge, etc or does it happen randomly? The next time it does it can you verify fuel pressure & flow before the engine cools off?