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

engine knock

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Old May 17, 2008 | 10:19 AM
  #1  
cstw01230's Avatar
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Default engine knock

Hi All, I hope some one can help me before I have my 93 LT1 engine put back together, My corvette started knocking on turnover and the knocking goes away under acceleration,it is a real knocking noise when you start it up and listening to the engine we thought it was coming from no. 7, at this point we thought it may be the big ends or a cracked piston so stripped it down the engine and all is fine, I checked the flywheel and that also is fine, Has anyone else had this problem and can you shed any light on how you solved it?

Thanks

Chris
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Old May 17, 2008 | 11:10 AM
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sounds like the "flywheel" knock of a ZF6. If you have a one piece flywheel, and get a miss in the engine (plug, injector, etc.) the transmission will rattle or knock. That's why they came with dual mass flywheels. If the rubber in the dual mass deteriorates you'll get the same noise.
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Old May 19, 2008 | 02:09 PM
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Default engine knock

Hi Fred,
Thanks for your reply, there was a miss on the engine before this occured, if we cure the miss will this make the knocking go away or will we have to take the transmisssion out?

Thanks

Chris
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Old May 20, 2008 | 12:27 AM
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I believe i have this same problem, well if it even is a problem. I dont have a miss or anything but what it sounds like engine knock to me but it only does it at idle, if i increase any rpms it completely goes away?

am i worried too much also?
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Old May 20, 2008 | 12:44 AM
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Stick? Does it subside for the most part or go away when you put the clutch pedal in?

What about when you shut it off, does it make a rattle/sharp knock noise like someone smacking metal with a hammer?

DM Flywheel.
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Old May 20, 2008 | 09:44 PM
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mine is a stick and the sound doesnt change with push of the clutch ped. mine makes a sound when shutting it off, like a rattle metal kinda of yeah.
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