Tetrylone

Have a bit of a knock or something on a new 4.0 in an 88 XJ. Piston slap? Worse?

It goes away above about 1500rpm and isn't there when the engine is cold. Once the engine warms up it comes on slowly. Sometimes it'll go away for a while if the engine is revved and then a few minutes later it'll creep back.

http://www.youtube.com/watch?v=http:...?v=HPkFOpUUdyQ

89Laredo

cracked exhaust manifold, if that slight hissing sound is part of what youre talking about.

Tetrylone

Nope. New exhaust manifold. The hissing i think is just poor mic quality.

Tetrylone

No one else wan't to take a crack at this?

Tetrylone

47 views and no one even wants to guess?

xj_maniac_newb

well since you just want a guess, im thinking maybe you installed some new percussion pistons?

Tetrylone

ahaha!

Tetrylone

Still nothing huh? There has to be someone who's seen this before.

xj_maniac_newb

yup, figured i'd throw a little comedy in there

95Cherokee

I didn't hear anything.

EvilMaster

Sounds like a washer vibrating in a loose bolt somewhere.

FOXxX

Could be anything from ungreased pulley, bad engine mount, or throttle cable tapping the side of the cab. If it is a new engine it could possibly be a lifter that has losened or wasnt properly secured and the valve is slapping. That would be the first thing I'd check.

tj40

If its a auto(aw4) torque converter bolts are loose, first. If not loose or not a automatic, alternator, second. if not alt. water pump or idler pulley. Take the belt off and start it. if its quiet its a accessory. The last area would be exhaust rattling on the cross member or floor? sounds like a alt. to me. Sorry for the ramble- a little drunk.

Bustedback

It's not piston slap. An inline six will not have much of a problem with piston slap.

tj40

To me it sounded more like a rubbing noise. I would call it something worse after the easy stuff is ruled out. Whats up with all the sarcasm in the Cherokee forum?