thejerry

So i finally got a Jeep after years of wanting one i got one, its a 1993 grand cherokee 4.0 liter with about 200k miles, i put new brakes rotors and calipers first off and noticed a slight knocking sound under the hood and noticed the valve cover gasket needed replaced so after racking my knuckles a dozen times i got it fixed, it needs and oil change so thats tommorows mission, but the knocking is what concerns me...what could it be? rod bearings? or the main bearings? or possibly the torque bolts are loose? i dont know. i hope its a simple fix, it doesnt affect the performance yet but i dont want it to get that far. any help would be greatly appriciated cuz its been a dream of mine to own a jeep for a long time and i would hate for this to be a major problem with it.

MallCrawlXJ

rod knocks are pretty common. prob the first thing to go on a 4.0L is the rod bearings.

Donnie_K

WHAT!?!? yeah... at like 400,000 miles or so




Hey bro, go down to autozone and get a stethoscope for like 10-15 bucks and see if you can find where it's coming from.

MallCrawlXJ

after owning 30+ xjs, 4 mjs, 4 yjs, 5 tjs, and 2 zj's.....i know a common prob. only two of them had over 200k miles, and 35% had rod knocks at some point. i just go off experience here, not what your jeep has done. i just sold an engine yesterday to a guy with a tj, 140k miles, and he had a rod knock......but hey, what do i know? right? (i may have a degree in automotive applied science)

i agree with getting a stethoscope to further diagnose your prob. i didnt say thats your prob.......just that its a common prob with 4.0L that are worn. you dont know how well the prev owner/s took care of it.

a few other common problems that cause knocking sounds are, loose flex plate bolts or cracked flex plate, loose wrist pins/piston slap, and valve ticking........google it. you will find how common these problems are, and how many threads have been made about them, even on this site!!

i dont mean to sound jerkish about it, just everything i say on this site turns into an argument. i will just keep to non-tech threads......as i dont argue well.

thanks and hope that helps OP.

thejerry

thanks, i think i may have found it, it sounds like the exaust manifold is loose at least i hoope that is the problem, also noticed one of my pulleys needs replaced but thats pretty simple, so hopefully my problems are as simple as they seem cuz if not this looks exspensive....