You should get 250K plus easily out of the 2.5 and the 4.0L. Even abused. The timing chain depends on how the miles were put on. I have seen them go the lifetime and seen them go at 120K. If its just the timing gear and chain. Replace and see what you have.
Puddles of oil are just a Jeeps way of marking its territory! LOL
If your main seal is getting bad then you are looking at a little work. Still not a deal breaker though. See what you are dealing with first.
I have recently bought my jeep and it ran great till the next day when i brought it home. I ended up playing around and touching everything not knowing the issue and it started again. Later of course when i went out of town for work it died on me and i found out it was the ground thats one the engine just behind the oil dipstick. No corrosion so it wasnt my first guess but there was enough oil on it to make it not work. cleaned it up with some gas and was good to go.
Well Rett, I went out to the shop today, pulled all the plugs, pulled the distributor cap and verified that with #1 cylinder at TDC the rotor lined up with the paint mark I'd made on the housing under the #1 terminal. It still did. So then I ran three compression tests on each cylinder. Here are the results in PSIG:
So just to be sure that I wasn't seeing bad rings, I shot a couple of squirts of 10W - 30 into #3 cylinder and gave it a few minutes to spread out and seal the rings. The readings with oil in #3 were 55, 55, 55. I don't think I need anymore proof that the timing chain has jumped. Sooo...can someone recommend the best timing chain and sprocket set available?
Well folks, I found the source of the problem. No question about it, the ol' four-oh jumped time...big time. The timing cover has two serious trenches in it almost all the way around. The timing chain is shot. No, the timing chain is beyond shot. Not only are the rollers visibly smaller than they should be, at least a couple of them are completely gone! Missing in action! The fact that it ran this long is a testimony to the toughness of these four point oh's. The good news is there is no groove in the harmonic balancer snout. But this question immediately came to my mind: Where did all that metal go? We can assume it went places I don't want it. So now I'm soliciting votes: factory rebuilt crate engine or rebuild the one I have? Let me know what you think.
Que89YJ - Yes, you were right. I even posted on the first page of this thread that it acted like the timing was severely retarded. So it is. And I know these engines are good for 250 - 300K miles, but there are rollers missing off the timing chain. As in completely gone! Where did those bits and pieces of the timing chain go? I'm just a bit paranoid about putting this motor back together as is after seeing the carnage under the timing cover. At any rate, I will have to wait until I can get a new timing cover, because the original has trenches cut in it. I haven't checked their depth with a dial caliper yet, but my calibrated eyeball tells me the wear is just about through the sides of the timing cover. I have serious reservations about putting it back together like that.
I tried Chris but got an error message at his mobile site. I went ahead and ordered a new Dorman online. But I've been thinking (that almost always gets me in trouble): The grooves in the timing cover average 0.025" deep, the chain guide and its cast in bosses are gone, the timing chain rollers are missing and sprockets are badly dished out. Here's the kicker; there are hard black baked on carbon deposits covering the inside of the timing cover. On engines I've run from new or near new and kept the oil changed in regularly, you can wipe off the deposits. This stuff is burnt on, like the P.O. had a serious aversion to oil changes. What's more the timing cover gasket was coated in red RTV so someone's been in there before.
At the very least I should pull the oil pan and clean out the debris. Afterall, those roller pieces, all that plastic and aluminum are bound to end up somewhere that won't do that motor any good. So I'm about 99% convinced I need to go ahead and pull the motor down and at least inspect it for wear. I previously found the water pump leaking by a bolt that was too long, shimmed with lock washers and the gasket was coated in blue RTV, so we can safely presume that was done by a jack-leg. Within the last 20K miles I've had to replace the transmission and rebuild the transfer case. I'm beginning to wonder if the drivetrain and engine were even originally out of this rig and just what all has been done to it. I simply don't trust it now based on the evidence. I'd hate to think the dealer may have misrepresented this vehicle... That being said, I'd like to *build* the engine while I have it out, rather than just rebuild it. I don't have any need to go the stroker route, although it appeals to my gearhead side. Do you have any suggested reading on what I can do to improve performance and reliability (within reason) while still keeping the old gal an OBD I 4.0?
Most of the stuff to improve the performance is easily done after its together and running right. I wouldnt do a single thing other then the chain and clean and inspect like you have said until its running 100% again. There is stuff like injector swaps, manifold porting, etc. that is done easily after it is running good. The 4.0L is about the most bullet proof motor you will find. Clean up the PO's mess and I think you will be surprised how much better she will run with the new chain and gears.
Que89YJ - I was already pretty impressed with the results from new injectors, a Borla header and cat back and the AFE cold air intake I installed a couple of years ago. I didn't touch anything else and it ran great, well until... Is it feasible to pull the oil pan without pulling the engine? I guess you'd have to break it loose from the mounts and jack it up.
I figure as far into it as I am right now, pulling it all the way out and getting it on the engine stand is probably the way to go. That will make performing a full inspection a lot easier, along with replacing the rear main seal (which now "marks its territory" as you pointed out) and the pan gasket. I hate doing things halfway; that's how you end up with a mess like the one I have now. As an aside, the CEL came on in my wife's Explorer and the MIL is flashing in my Miata. I realize they aren't jeeps, but they are both OBD II. So I can check OBD II functionality of the Actron scanner for you real soon and post the results on the other thread.