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[Bubba]

i am wondering about this we all know the 4.0 is great engine but apart from manifold issues [some years] do they fail on anything like valve train or other probs
i have over the years noticed on some that on tick over when warm a very slight rapping noise almost like timing chain or crank end float in a horizontal plane or similar

lee sheps is one that springs to mind but it has never had any engine problems so i know its a harmless noise but i have noticed this on a few but that lead me to wonder just how reliable are they

[isle of man]

I have never had one fail on me - god knows I give them a hard time - just keep changing the oil and they are good to go!!!

[wildwood]

When I had my UK 93 YJ .........( still going in the hands of another Birty with over 100k on it......) I was worried about a noise as it only had 18k on it... It turned out that some of them had piston slap and that it was caused by an inferior coating on pistons and that there had been complaints but no warranty issues.....

But.... as I said motor still running.... I did hear this from at least 3 people over the last 10 years so its either the BS grapevine or maybe true???

[Bubba]

yup piston slap could be the niose i have heard

[JamesH]

There is a later model cylinder head that can crack I believe. The only failure I've seen is one that knackered it's bottom end but I'm almost certain that was dirty oil or run out of oil. They do make some funny noises and generate a lot of heat, especially in a Cherokee.

[scrw]

yep, a couple of years had the cylinder head issue (2000-01?) piston slap on some earlier ones. Mine has an annoying tick below 1500rpm that sounds like timing chain issues but has been like than for a year or so, plus it has over 180,000 miles on it at the mo and climbing about 3k a month. WJ/G's didn't seem to get the header problems as they are 2 piece ones instead of 1 piece. Later DI coil packs aren't as reliable as the dizzy/coil arrangement in my experience, never had to touch the dizzy/coil setup in 200-odd thousand miles of driving an I6 but have had 2 DI coil packs go on the current WG, think the vibes may get to them or I got unlucky with duff parts

[gordy]

yep, a couple of years had the cylinder head issue (2000-01?) piston slap on some earlier ones.

I'm no expert, but I remember reading that is was something to do with getting the emmissions down..that resulted in 00-01 MY cylinder head issues.

[Green Jeep]

My earlier YJ 1993 has a noise which could well be piston slap, never changed in the years I've had it so never worried me, the XJ 1996 I have is real sweet and defo pulls stronger. Manifolds do crack, changed one on the YJ recently, few hours work, nice and quite again now.

I always use Mopar oil filters (from Lighhouse) worked in automotive filtration for ten years, would never fit cheap filters and American made ones have the by pass valve at the top, making them IMO better.

Hope this helps, cheers Maf