C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

cracked flexplate???

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Old Feb 15, 2004 | 02:49 PM
  #1  
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Default cracked flexplate???

im getting a knocking noise from the engine/tranny but it goes away when the car is in gear or while im driving,is there any way i can check the flexplate? i have good oil pressure, if it was a spun bearing would the noise constatly be there? even with increased rpm?
car specs:
94 lt1 a4

thanks!!!
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Old Feb 15, 2004 | 03:31 PM
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Default Re: cracked flexplate??? (eguti66)

anybody?
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Old Feb 15, 2004 | 04:45 PM
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Default Re: cracked flexplate??? (eguti66)

I believe there is aflywheel cover that can be removed for inspection of the flex plate. It certainly can cause a racket if it is broken or has loose bolts. It's the first thing I would check. :cheers: :cheers:
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Old Feb 15, 2004 | 08:09 PM
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Default Re: cracked flexplate??? (dwestsr)

There is an aluminum cover plate that can be removed to inspect the converter and flex plate. If there is a crack it will be in between the HUB area the converter bolts! I thought / wished my noise was a flex plate crack but it was a spun #7 & #8 main bearing!! I fixed mine in place by repairing the crank and replacing the bearing! Car is still running GREAT! Had to use a 0.010 under bearing after massaging the crank to the correct specs. It will go to red line when ever you desire without a problem!!
BC
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Old Feb 15, 2004 | 08:41 PM
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Default Re: cracked flexplate??? (Bill Curlee)

but it was a spun #7 & #8 main bearing!!
Was that on a V16? Or a straight 8? What year Corvette?
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Old Feb 15, 2004 | 08:44 PM
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Default Re: cracked flexplate??? (CFI-EFI)

Woops Spun #7 ROD bearing! :thumbs: I took the V16 out because I had to go thru an Emissions check! :D

BC
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Old Feb 16, 2004 | 09:28 AM
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Default Re: cracked flexplate??? (eguti66)

thanks for your replys :thumbs:
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Old Feb 16, 2004 | 01:07 PM
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Default Re: cracked flexplate??? (eguti66)

If it is a cracked flexplate, you will found out fast enough. It won't last long being cracked, and then you will sit in one place until fixed. Don't ask me how I know this. :crazy:

Plasticman
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Old Feb 16, 2004 | 07:09 PM
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Default Re: cracked flexplate??? (Plasticman)

is this a common problem with these cars? im just hoping its not a spun bearing :cry , i dont have a chance to check it out until this thursday hopefully it is the flexplate!


[Modified by eguti66, 12:31 AM 2/17/2004]
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Old Feb 16, 2004 | 11:38 PM
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Default Re: cracked flexplate??? (eguti66)

I had one fail (thankfully while in my garage on startup), but also found the bellhousing bolts were loose causing the plate to flex alot more than it normally does. I was able to replace the plate without removal of the engine or trans, but it was not "fun".

Plasticman
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Old Feb 17, 2004 | 08:01 AM
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Default Re: cracked flexplate??? (Plasticman)

Your best bet is to get the car up on a lift OR high up on 4 jack stands, remove the aluminum inspection cover, remove the 3 converter to flex plate bolts and slide the converter back to inspect the plate. I used a small pry bar to FLEX the flex plate to make sure that there were not any hidden cracks.

In my case the flex plate was in in good shape. The only thing that was left was to drop the oil pan! :( Once I had it off I saw that #7 connecting rod had a loose rod bolts and the bearing had spun! I caugt it in time before it killed the crank journal.
Dont be afraid to drop the oil pan. It comes off relatively easy, and it can be done IN PLACE!


BC
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Old Feb 17, 2004 | 08:13 AM
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Default Re: cracked flexplate??? (Bill Curlee)

I too had a cracked flex plate a long time ago in my Nova, and it happened twice. I then changed the crank,converter and trans and no more probs. I was only a teenager when it happened, and I drove on it for quite some time before I fixed it- the second time. The first time I tore off the pan, and even removed the heads looking for the noise before I found the cracked F plate. Mine had cracks between all of the bolt holes that secure it to the crank, no where else. They would be hard to see, even with the converter slid back. BTW- It can be changed without pulling the trans. One time I had to use longer bolts in the engine to trans (two, while removing the rest) to slightly separate them to get it out. The other time I think it cam out fine. Have an assortment of wrenches you can treak with the "blue wrench" to get the best access.
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Old Feb 17, 2004 | 09:50 AM
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Default Re: cracked flexplate??? (eguti66)

thanks again :thumbs:
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