lsejlowe

I'm new to the forum and hope one of you guys might be a 4.0 expert. About a year ago my g/f's '94 Cherokee Country developed a loud tick. It starts and runs fine, doesn't seem to be lacking any power, and has good oil pressure. However, it hasn't been very well maintained for its 232,000 miles.

I just replaced the rod bearings and the tick is unchanged. I had a look at the flexplate while I was down there and couldn't find any sign of cracks. Looked at all the cam lobes and none seem to be particularly worn. Took the valve cover off and saw nothing out of place. No loose rockers, no bent pushrods, no broken springs. Using a stethescope the sound seems to be loudest around cylinder #5 fairly low on the block.

At this point I'm assuming it's a lifter, but I have no motivation to pull the head off this oily greasy mess of an engine. Only other thing I can think of is a cracked exhaust manifold, but I haven't been able to detect any sort of leak. How's a guy supposed to get a good look at the welds with the intake still installed?

I took some video of it so you guys can have a listen and let me know what you think.



Sorry for the long first post!

Howler_GT

The dreaded 4.0L TICK.

With all you said, the thing that stands out the most is the "hasn't been very well maintained for its 233,000mi.

Ticking 4.0L have one of two problems. (Some have both)

Lifters:
Most times sticky lifters will give you the ticks. Although, not often a problem, it is rather ANNOYING. With 200,00+ on the clock, I am willing to bet the insides of the motor leave alot to be desired.
CURE: Replacement? Yes, IF you feel like yanking the head. Alot of XJ owners resort to a heavier oil or one with a bit more detergent additive. Over time the ticking will lessen. Heavier oil a cure-all? By no means. BUT it is a relatively cheap band-aid.

Manifold: The exhaust manifolds on the 4.0L are prone to cracking. Many have re-welded the manifold (its merely a tube-style manifold) but sadly they often re-crack. Replacement is the only viable option on this one. Replacement manifolds can be obtained on eBay rather cheap. Look for the one guy that has the FREE shipping. I got BOTH of mine from him and I couldn't be happier (I have 2 XJ's, thats why I got 2 manifolds from him.

troy fritz

You cant see the piston from the valve cover. But 2xs on replacement.

lsejlowe

don't think I mentioned any pistons. I looked for bent pushrods and broken springs, but no pistons. When I pulled the pan there were no chunks in the bottom. No broken rods, no sign of piston failure. All 6 rod bearings were very very worn, but the main bearing clearances were all right at the spec of .002" in spite of a few grooves.

rod bearings:



main bearing clearance:


I might try some heavier oil and some additives. Certainly beats dealing with pulling the head... Thanks for the tip, Howler.

Mike H.

that sounds like valves hitting pistons to me.
A valve spring does not have to be "broken" to be worn out.