MJKally

It's the european 2.5L turbodiesel, not the AMC 2.5L. It's curious, but convenient that the 2.5 diesel bellhousing is the same as the 4.0, but it's good for me. It would be nice if the master is just a direct replacement, as you can buy those complete pre-bled systems, but if I have to use an old master with the new slave it'll be fine too.

Bumping this one to save making a new thread, My replacement AX15 from a '99 XJ turned up this week, so I've pulled my transmission. Apparently what I’d read about the 4.0 and 2.5 bellhousings being different is wrong, because the bellhousing that came with my transmission looks like it'll bolt straight up to the 4.0. I'd like to use it and switch to the external slave cylinder. The master is a bit suspect and the hose is worn out so I'd like to replace the whole clutch hydraulic system with a newer setup. Do i need to keep my original style master cylinder, or will the newer, plastic one fit the same holes? I can't find any measurements to compare them but the pictures make them look pretty different.

Finally a bunch of parts and the replacement transmission turned up this week, so today my brother and I ripped the old transmission out. It wasn't too bad a job, but I made several discoveries along the way. Firstly that the transmission jack I have sucks. Second, I'm not really sure if the transmission was even the problem. I set the new one (from a 1997ish 2.5TD XJ) and the old one side by side, and they both feel about the same going through the gears, and none of the gears feel loose like the shifter is about to slip out of them. I don't know accurate of a test that is, but it was interesting. I already know the clutch wasn't bled properly so I'm starting to wonder if that was the problem. The clutch, pressure plate, and the internal slave are nice and shiny and new, but the flywheel looks pretty hammered. I don't know if these can be resurfaced, but the last time I took a flywheel to my local transmission shop they said they don't resurface them any more. I might ask around and see if anywhere will, but replacing it isn't expensive, so I’ll probably just do that. I'd read up on it while shopping for a gearbox, and it seemed like the 2.5TD and 4.0 bellhousings were not the same, so I thought I wouldn't be able to use the bellhousing from this transmission. Now i have them both side by side, they sure look the same to me. I'm going to try bolting the newer one up tomorrow, and if it fits I'll order an external slave cylinder and a new throwout bearing for it. Also going to order a new master cylinder, as despite my best efforts to plug the disconnected clutch line, it's still leaked all its fluid out and if it's anything like a brake master, it'll probably need to be removed and bled. So I may as well just fit a new one while I'm at it. The other thing I've learned while crawling around under the Comanche is that it needs a rear main seal. I thought you'd need to pull the transmission to do that like on some other engines, but it sounds like on the 4.0 it's actually really hard to do without the transmission holding the engine up, so that job can probably wait until I can get it over a pit at work.

Some updates, I bought a used transmission and I’m just waiting for it to turn up. I think I might have ordered the wrong pilot bearing though, or the wrong clutch alignment tool, the fit between the tool and bearing is like throwing a hotdog down a hallway. I ordered them based on part numbers I was given and I now have some doubts, so i just need to wait for the transmission to turn up so I can actually measure things. The renix engine monitor I ordered also turned up, I plugged it in and confirmed that the reason it smells like it's running rich is because it is. Not exactly sure why yet, I fixed a vacuum leak too this morning but I didn't run it for long enough to be able to tell if it's actually helped. I haven't really looked too much at the other readings yet but I'm really impressed with all the information it can give you, I was kind of against buying it at first as i wasn't sure how much I’d need it, but so far it seems like a good buy. Last week I poked all the wiring and discovered that my oil pressure sending unit was bad, I replaced that this morning and now I can actually see my oil pressure, just over 40psi at idle. I looked it up, and apparently that's fairly healthy and normal, but I wonder how much that'll change with some fresh oil. It's encouraging, anyway. I think I now have a full set of working gauges. I'm not 100% sure the fuel gauge is working properly... but the sending unit seems to share a ground with the fuel pump, and that seems to be working fine, so it may just actually be empty. I also figured out why my horn doesn't work. The relay wasn't clicking, so I replaced that. Still wasn't clicking, so i popped the horn button apart and cleaned that. The relay clicks most of the time now, but the slip ring is apparently dirty too as it's a bit unreliable. I have a steering wheel puller somewhere, so I'll probably pull it and clean it fully at some point. The main issue is that the horns are completely junk. I pulled one off and hooked it directly to the battery and it doesn't make a sound. Not really a huge problem at this point but it's nice to know what the issue actually is.

I ordered it from NickInTimeDesign.com, someone I know with an XJ recommended it to me, and I think someone on the forums did too.

I picked up this 1990 Comanche Pioneer a few weeks ago. it's a 4x4, 4.0, 5 speed manual shortbed model that's apparently been sitting for 20 years. The guy I bought it off replaced the whole fuel system from tank to injectors, replaced the clutch and got it running before giving up, so now it's my problem. I didn't need a third project car, but here we go. It's pretty clean for a 36 year old car, very straight and minimal rust. It has one small hole in the floor and a couple of pinholes in the roof, but those can be fixed pretty easily, then the whole thing is rust-free. I plan to paint or undercoat it before too long to protect it, but for now I'm just focusing on getting it back on the road and able to pass inspection. The biggest issue is the transmission needs replacing, and the clutch needs bleeding properly. 1st gear is essentially unusable, and it grinds going into the others. Rebuilding it would be nice, but even if I do it myself it'd be very expensive. I have a line on a replacement, but I’m just waiting to hear back about it. Besides that, the only other problems are mostly just age related. The engine obviously needs servicing and going through to make sure it's running right, but it does run, so it's a pretty low priority at the moment. It needs every suspension bushing replacing, new shocks, new U-joints, new oil in the diffs and transfer case etc. I plan to maybe rebuild the axles at some point down the line. Eventually, the goal is to clean it up a bit and make this thing a daily driver. I'm not going for a full restoration or upgrade, just trying to bring it back from the dead. Here it is stinking up the driveway with my current daily/1st project car, my '90 S10 Blazer.

I had the whole cluster apart to clean the contacts last week, I didn't remove the needle but it's possible I knocked it or disturbed it while it was apart. I'll try that, thanks! I've ordered a renix engine monitor, so I can check to see if it's calibrated with that whenever it turns up.

I'm working on getting my 1990 4.0 Comanche back on the road, it's sat for 20 years and many things aren't working. The entire gauge cluster was dead, so I recently took it out, cleaned all the contacts and checked them all for continuity. The gauges mostly work now, except my tach is reading below 0 when the engine is running. If I give it some gas, the needle does go up, but the resting position while it's running is this: I have an original service manual with electrical diagrams, but it doesn't make it obvious where the wiring for the tach goes, or what to do if it's out of calibration. I've already gone through and cleaned as many grounds as I could find, all the connections in the IP seem to be good now. What would cause this?

I did some reading, and it looks like I’d need a different bellhousing to use the external slave cylinder. I could potentially find one, since I think some of the wranglers sold here would've come with the 4.0 and the AX-15, and they would have the bellhousing I need. But, I need a transmission now. And I can't really wait around for one of those to turn up, so that can be a potential future upgrade.

The replacement transmission I'm looking at is out of a '98, so it looks like it has the external slave cylinder. If it's all in good working order then I see no reason not to keep it.

Thanks for the advice. It looks like I’m going to have to disconnect the clutch hydraulic lines to get the transmission out whatever I do, so I'll have to bleed the system again when it goes back in. The previous owner, who installed all the clutch parts, did say that he'd bled it and it was apparently difficult to do on these, so any pointers are welcome. I've bled my fair share of brakes, but never a clutch, so I'm not sure if the process is any different. As far as the transmission itself goes, I was thinking a rebuild was my only real option, since I was under the impression they were hard to find over here in the UK. I did a little research, and it turns out that the UK spec 2.5L turbodiesel cherokees all came with the AX-15 untill 1999. I wasn't getting any results for AX-15, but I looked up 2.5L TD cherokee transmissions and found several options. I'm currently looking at one that's less than the cost of a rebuild kit, the seller is going to send me some more pictures, but if it checks out then I’ll go with that option. It even comes with the shift knob, which mine is missing.

Hello, I recently picked up a 1990 4.0 Comanche as a project, with an AX-15 5-speed transmission. It was sat for 20 years until someone bought it and did some work to get it back on the road, they got it running and put a new clutch, clutch master, and clutch slave cylinder on it and (apparently) bled it, then ran out of time and money to work on it so they sold it to me. How much they knew about the issues I'm about to describe is anyone's guess, but it's my problem now. The transmission pops out of first gear pretty easily. It doesn't click into place as nicely as the other gears seem to, and if you give it some gas, it makes a bang and pops out of gear. if you try to hold it in, it grinds and tries to kick the shifter out. Second gear works just fine, and I’ve been using it in place of first to move the truck around, since it seems to be able to set off from a dead stop just fine in second. I haven't driven it far enough to get to third or fourth gear yet, but they seem to shift okay. The other issue is that it gets stuck in reverse quite a lot. I suspect this is a clutch issue and it maybe needs bleeding more, because it refuses to disengage unless you push the clutch pedal to the floor and into the carpet, that just seems excessive. I am aware that there's a technique for shifting into reverse on these boxes which I haven't quite learned yet, but it getting stuck in reverse seems to be more than just user error. I know that I'm in for a rebuild, but what can i expect to be replacing? The rebuild kits for the AX-15 all come with the syncro rings, but I don't know if that'll be enough, or if i'm going to need to replace gears or the sleeves on the shift forks. Thanks.