I have a 92 with a 4.0. It has some serious low end noise. sounds like a main or rod bearing but we have been driving it like this for about 1 1/2 years and it seems that if a rod was knocking or a main bearing it would have come unglued by now. I thought it might be a vibration dampener but that's not the problem. Is this a common problem with jeep4.0 engines? any ideas?
serious engine noise
- Thread starter ubee
- Start date
SteelHeadz
Super Moderator
92? with a 4.0?, the only engine i know that was available for that YJ in 1992 was a 2.5 4cyl. anyways, is it misfiring?
Bounty__Hunter
Super Moderator
The 4.0L was available from '91+, it replaced the carbed 4.2L ( 258 )in the YJ.
How do you know it's not the vibration dampener? I've heard it has similar symptoms. Could also be a busted piston skirt but I would have thought it would have let go by now.
How do you know it's not the vibration dampener? I've heard it has similar symptoms. Could also be a busted piston skirt but I would have thought it would have let go by now.
Hi ya,
You might want to look at my 2006 Jeep Liberty post. Although your issue might not be as serious, I definitely wouldn't 'let it go'. A minor issue could end up being a major issue. In my case, the issue was major and went to catastrophic in seconds, but that's obviously isn't your case. Lucky you!
You might want to look at my 2006 Jeep Liberty post. Although your issue might not be as serious, I definitely wouldn't 'let it go'. A minor issue could end up being a major issue. In my case, the issue was major and went to catastrophic in seconds, but that's obviously isn't your case. Lucky you!
SteelHeadz
Super Moderator
Yup! your right. My head is not screwed in correctly. sorry.
I bought the vehicle as a 92. the engine is a 6 cylinder and all the parts that I buy for a 4.0 seem to fit. i replaced the vibration dampener a few years ago with an aftermarket " Dorman " brand. It doesn't appear to be rubber mounted like the OEM unit that failed. Yes it is mis-firing and i notice that if I keep the rpm at 1000 or above the problems seem to dissappear. Sure would like to solve this thing if anyone has ideas. Thanks for all the reponse.
SteelHeadz
Super Moderator
My suggestion is to pull the oil pan and check the main and rod bearings. and while your at it, if you could also look up on the Cylinder walls for abnormal marks that may be caused by a failing piston wrist pin.
elevatorman
New member
I once bought a 67 Chevelle Big Bock with a rod knock for $500.00.
Pulled the oil pan and found that the previous owner had dented the pan and the crank throw was hitting the pan. It was louder at idle than when I reved it up.
Replaced the pan and drove that car for 8 more years
Pulled the oil pan and found that the previous owner had dented the pan and the crank throw was hitting the pan. It was louder at idle than when I reved it up.
Replaced the pan and drove that car for 8 more years
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