knock ?

[ChipsXJ]

92 xj 4.0 165000 miles with bad knock.

restore does not help.
flex plate bolts tight.
pulling spark plug wires do not make sound change.
knock speeds up with rpms but does not get worse.

any ideas? exhaust manifold is cracked. will cracked exhaust manifold cause knock?

[riverfever]

My manifold is cracked real badly. I wouldn't call the noise an exhaust leak makes a "knock". Almost more of a tick. Can you use a section of fuel line like a stethoscope and get underneath it and see if it's more pronounced by the oil pan?

[ChipsXJ]

here is a bad video of it:
http://i2.photobucket.com/albums/y16/ChipsXJ/th_000_1316.jpg (http://s2.photobucket.com/albums/y16/ChipsXJ/?action=view&current=000_1316.flv)

[waxer]

Yah that sounds like crap.

Get underneath it and start touching parts of the engine, specifically the oil pan, where the front and rear main seals are, etc... Try to feel where the ticking/knocking sound might be originating.

Also use the fuel line as a stethoscope to see if you can find where its coming from

[langer1]

Try it with the fan belt off.

[dgrigorenko]

i have a 99' with 168000 that has the same sound coming from it, although not as bad, and i also used to have a 91 yj that sounded more like yours. i am not exactly sure what it is, but on mine it always seems to be coming from inside the intake manifold. i am not sure what to do about mine either, so if someone knows anything i can use the help as well!!:D

[ChipsXJ]

gonna crack her open this weekend............will update when I find out what it is. I am leaning/hoping towards valve train components.

[Creech]

Sounded like a lifter tapping mixed in with the broken exhaust manifold. Fix the exhaust and it will be easier to narrow it down.

[citRon]

any updates?? I'm battling this right now...
http://www.naxja.org/forum/showthread.php?t=104405&highlight=noise