Geonovast

Hmm.. just checked the other thread and see you've done that. Replace the fuel filter, if that's getting clogged it could cause low pressure, or your pump is on the way out.

I would do a whole tune up (plugs, cap, rotor, wires) before you worry about timing. The only way the timing could be off is if someone indexed the dist, the chain slipped, or something flat out broke. If the dist was indexed they would ALL miss if it even ran. If something broke you'd have a problem, with the 4.0 being an interference motor.

I doubt it's the resistor, since I replaced it less than a year ago when the pump died. I was out there today and replaced the ECU (had one sitting around, figured I'd eliminate that), and I noticed the vacuum elbow fitting on the pressure regulator was cracked...everywhere. I replaced that and I'm going to be taking it for a test drive pretty quick to see if that did it. After seeing that, I thought it could be the culprit, since when the fitting was cold it might seal, but after the engine bay warmed up and the fitting expanded, it would start to leak. Then when I let off the gas, the injectors wouldn't open as much and allow the pressure in the rail to build back up. If this isn't it I'll have to swap CPS, and if it's still acting up after that I'll go to the pump. Again. I don't want to grab the CPS off the 4.0, with it being so close to the firewall I'm sure the bolts will get away from me. I do however have two CPS's sitting around with the newer style plug (see pictures above) If I splice wires, can I use those?

:clapping: It might. Gas doesn't cause rust, water does.

Ahah! You have actually done this? I have always maintained that it's possible, but the shop foreman at my dealership swears it can't be done so I never pursued it. Thank you, thank you! How hard a job was it to accomplish? I had a thread on it awhile ago but it never quite got finished(the thread) If you know what you need to do when you get into it, it's actually fairly simple. The splines on the output shaft for the gear are sitting there waiting for you, and the splines on the layshaft are there, but the AX-4 has a round piece of metal in place of the 5th gear, I would assume for balance and a placeholder. That, and the reverse/5th sliders all have to be changed over, but that's easy. I did screw up two things though, which is why I had to pull that trans. I didn't have the spring/ball setup done properly so the trans could go into two gears at once(happened when I installed the shifter, almost had to pull it again), and it wouldn't stay in 5th unless you held the shifter forward. That was accomplished with a hose clamp and one of those hooks you'd use to keep a door open. The other was the nut on the back of the layshaft. You have to make sure the crimps on it are set or it will work its way back. I lost 5th before I pulled the trans, because that worked back and the gear pulled back too far to engage. Come spring I will pull that apart and do a full write-up on it so it can be done properly. Saying an AX-4 can't be converted to an AX-5 is like saying a 2wd MJ can't be turned into a 4wd one.

Best bet would be to replace the master cylinder. I had the same problem on my 88 XJ. A little over $100 but it'll solve your problem.

My 2.5 came with a 4 speed and 3.55. I put the 5 speed tranny from a 93 XJ in it and the 4.10 D30/8.25 will be going in it in spring. 3.55 with 4 speed (4th 1:1) final drive is 3.55 4.10 with 5 speed (5th 0.85:1) final drive is 3.49 The AX-4 and AX-5 are identical with the exception of the AX-5 having the fith gear. (I know this, having put the fifth gear from an AX-5 into an AX-4 to make it a 5 speed.) 1st 3.93:1 2nd 2.33:1 3rd 1.45:1 4th 1:1 5th 0.85:1 R 4.74:1

Muffler on my 2.5 just fell off, again, so I said screw it, and threw in a piece of pipe. Both trucks are just a cat now. It's quieter with just a cat then pipe than a cat, muffler, and then nothing.

Cherokee shift linkages will be identical for your MJ. So if you get the linkages from the same XJ that your tranny and T-case came from, it will work perfectly. Did you swap your front axle yet? If not, you can use the one from that XJ too if it's the same gearing as your current rear axle.

Did you check the torque on the head bolts before you removed the head? They may have simply been not torqued down enough in the back and that could cause the head to not sit flat.

I would never re-use a cork gasket. Get the one-piece rubber one, it's usually the same price, and you can re-use that one. When I bought the gasket set for my 88 4.0 it came with a rubber one, and it was a Fel-Pro set.

The BA 10/5 was used behind the 4.0(which replaced the 2.8 ) in 87-mid 89. There should not be a BA 10/5 behind your 2.8 since they didn't put them there. As far as I know, there's no bellhousing that exists to do it, unless you have one custom made. I'm not saying it's inherently bad that you have it if you do, since the 2.8 shouldn't be able to kill it, but it shouldn't be there. It'd just be interesting to see, so if you could get a pic that would be schnifty. 2.5 I4 - AX-4, AX-5 2.8 V6 - AX-4, AX-5 4.0 I6 - BA 10/5, AX-15

Another possibility is your internal slave could be leaking. Any clutch problems?

No gasket on the bellhousing as there should not be any fluid in there. If there's oili coming from that, it's either trickling down from the valve cover gasket, oil pan gasket, head gasket, or the rear main is shot. Your front bearing retainer on your tranny could also be leaking. I know the AX-5 and AX-15 have them, I can't remember if a BA 10/5 does. If that's leaking it would pour out the bottom of the bellhousing.

I will, but that better not be since I replaced the pump last fall. Starts right up.

I did replace the O2 sensor with a known good one off a 92 4.0 when this all started in the first place and no change. I would try the two other CPS's I have sitting around, but they're both from 93/94 and have the rectangular plugs. Both my MJs have the circular ones. I could try the CPS from my 4.0, but pulling that thing off the trans and not having the bolts fall into the bellhousing is tricky. It's enough fun on a 2.5. I was thinking ECU, since I know the Renix era ones use a different set of preset values while it's cold, I couldn't remember if the chrysler computers did that too. It would make sense if it did, then the few minutes it was running weird would be the computer re-learning the motor. Could I use one of the rectangle plug CPS? I'd have to splice some wires I know, but they should be the same, right? On the left is what the trucks have (pic taken from 4.0 but plug is the same on the 2.5) and on the right is what the spare CPS is.

Yours should be a D35, unless someone swapped in an 8.25

I also had the same problem. It solved itself, since there was simply too much water in the system. Once it bubbled enough over it stopped, and stopped overheating. (88 XJ 4.0)

Replacing the relay would be the first thing I would check.

My 2.5 is acting up. Just got the AX-5 and 231 in there so I got my 4x4 back (207 locked up on me), and aside from my muffler falling off last night it's been fine... Except when it gets warmed up, for about 5 minutes, every couple of seconds it hesitates, feels like it's missing. If I keep giving it throttle, it starts backfiring. If I let off the gas, then give it again it's fine. After about 5 minutes it stops doing it completely. It did it once or twice a few months ago then stopped, but now it's every time I drive it. I wanna put my 4.0 down for surgery so I'd like this fixed before it gets toooo cold. I put on new cap, rotor, wires. I'm thinking either TPS, CPS, or ECU. I have a spare TB and ECU sitting around that I'm gonna throw in, but unfortunatly the CPS from the truck those came from had newer plug(rectangle plug instead of round one) Any other suggestions?

You said you had the 2.8 and your peugot tranny's bearings replaced? They didn't put the BA 10/5 behind the 2.8, your trans should be an Aisin AX-5. Unless of course by some 0.0003% chance it is, since nothing's certain on these things. If you could get a pic of the motor and trans from underneath, that'd be interesting to see.

Pete, I'm scared. Where am I? How'd I get here? Where's the couch?

That thing should be saved, not parted out for an axle. If you find a newerish XJ with a 2.5 and 5 speed you should be able to get a 4.10 geared Chryco 8.25

There's a few metal shavings in there...

Like day and night.