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04-27-2011, 03:16 AM | #1 | |
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Piston Wrist Pin Question
Is it possible for the piston wrist pin to get bad and lead to a knocking sound, and if so, what are the causes and remedies. My Grand cherokee has a noise in the engine on idle and three mechanics out of five say its due to bad piston wrist pins. Any suggestions?
Last edited by Moppie; 04-27-2011 at 03:56 AM. Reason: typo errors |
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04-27-2011, 09:40 AM | #2 | |
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Re: Piston Wrist Pin Question
Its very difficult to narrow down a knocking noise. Main bearings, rod bearings, piston slap, and pin knock all sound VERY similar. The mechanics are probably responding to the fact that pin wear is very common on Jeeps, especially the inline 6s.
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04-27-2011, 11:35 AM | #3 | |
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Re: Piston Wrist Pin Question
Thanks for the info, i guess i'll just proceed with a careful elimination tactics in resolving the problem. I have already had the main bearings and the push rods checked and they checked out fine, i guess the next thing to check on is the tappers and the wrist pins. Strangely the sound disappears on increasing the RPM and is louder on idle.
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04-27-2011, 11:36 AM | #4 | |
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Re: Piston Wrist Pin Question
Try and narrow it down by shorting out one cylinder at a time, see what changes.
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04-28-2011, 04:51 PM | #5 | |
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Re: Piston Wrist Pin Question
I can usually tell a pin knock very accurately , but many times it is the piston that's broke/cracked. A good engine shop can tell by listening and they are also armed with data such as what curtis posted about jeep pins because that is the business they are in.
possible causes clip came out/broke press fit became loose worn rod/piston broken piston seized pin/lack of lube can't really think of many more off the top of my head. Remedies are dependent upon cause. replace clip oversize pin new piston rebuild holes re-do lube top pin I can't remember ever seeing a pin break under normal use. |
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04-28-2011, 07:34 PM | #6 | ||
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Re: Piston Wrist Pin Question
Quote:
This does not mean you should neglect the noises...... it might be something serious...... then again, it may not. As I recall Chrysler updated the piston design, block and main bearings in 1996, which indicates (to me anyways) problems with piston slap and/or bearings were causing the noises. However, as I recall, noises did persist afterwards. |
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04-29-2011, 09:30 AM | #7 | |
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Re: Piston Wrist Pin Question
Good point. My car has had piston slap since 20k miles. I now have 130k on it and the noise hasn't changed. Depends on what the noise is.
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