strange knocking + vibration
strange knocking + vibration So here is the scenario.. I put an aluminum flywheel and centerforce clutch(was properly balanced) in my car, put about 500 miles with no problems on it then one time I accellerated hard from a stop and all the sudden it has a terrible vibration over about 4000rpm. also since that happened it has been knocking. The weird thing is that it has no vibration if I rev it up in neutral(so i doubt it is the flywheel/clutch) and it only knocks when the engine warms up, guessing a rod bearing or something is going. Is it possible for a bad rod bearing to cause the vibration? or maybe a crank bearing? Anyone have a simillar problem?
Thanks
Curtis
Thanks
Curtis
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Joined: Jan 2008
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Does the engine make a hollow sound once for every stroke (rod knock) or does it have a double tap for every stroke (piston slap)? The clutch installation could just be a coincidence for a problem that was going to happen. A good method to help pin point the source of the noise is to use an automotive stethoscope and carefully probe around the engine. Be careful around all moving parts since you will need to have the engine running to hear the noise. If you’re in a bind you could also use a long screwdriver with the handle up to your ear but it will not transfer the sound as clearly.
It deffinatly sounds like a rod bearing knock and is coming from the crank area. I think maybe the aluminum flywheel caused added stress on the rod bearings by not keeping up the inertia. What confuses me tho is the vibration. I have had rod bearings go in other cars without causing a vibration(or at least a very very noticable vibration).
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Joined: Jan 2008
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From: Ohio, Georgia, Nevada, Texas
What is your oil pressure at idle and at 4000 RPM?
It is around the 3/4 mark at 4000 and drops to around the 1/4 mark on idle. only have gauge on the cluster so cant get very accurate pressures. This drop was also why i was thinking it may be a rod bearing but I thought it would drop lower with a bad rod bearing.
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Cut the oil filter in half with some tin snips and inspect for glitter. If it's a bearing, rod or main you'll know it.
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Dont forget to post an update with what you find! I hate when threads have no closure, especially when doing a search and you FINALLY find that one guy with the same problem
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Before assuming it's internal and since this started happening only after you put in a new clutch/flywheel I'd take the trans out to see if it's related to your latest install. It reads like it could be a loose flywheel. How was the flywheel/clutch assy. balanced?
I will deffinatly update in the spring, and yes youre right it could be just the flywheel. Not sure how it was balanced, I just dropped it off at the machine shop but it was balanced as an assembly if that helps.
It is deffinatly seeming that way. I think it may be a combination of things becasue it deffinatly sounds like it has rod knock but only when it warms up so guessing a bearing is going. I'll make sure I update in the spring when I pull it all apart! Also considering doing a 5.3 turbo swap and parting out my driveline.. that would deffinatly solve the problem, and give me a list of new ones haha
Here is a follow up in case someone has the same problem... although I dont have a deffinate answer. I finally got my car out from winter storage(yes I know I am a little late). Took the car for a drive and still had the vibration. However no knocking of any sort, not driving, not idling, not revving in neutral, nothing. I had my stock flywheel resurfaced and bought a new clutch. Put it in this past weekend and I am happy to say that my vibration is gone! Everything seemed tight and normal on the old clutch so I dont know what happened to make it suddenly start vibrating in the first place. Now the car is running and driving perfectly so I am just hoping that everything is fixed and that the knocking was something clutch related! Thanks to everyone for the helpful input!
