94 LT1 w/90K. Has a hollow sounding knock when cold at idle. Slowly fades away a engine warms up. Very noticable standing next to car or from inside, but can't hear anything remotely similar with a stethiscope anywhere on the engine. I don't know if it is anything to be concerned about but I would much rather it wasn't there. I use mobil 1 10W30 and has less than 500 miles on it. Any suggestions???? Thanks for any help.
-
Got the Contributing Memberships stuff finally worked out and made up a thread as a sort of "How-To" to help people figure out how to participate. So if you need help figuring it out, here's the thread you need to take a look at -> http://www.corvetteflorida.com/forums/showthread.php?t=3581 Thank you, everyone! Rich Z.
C4 Hollow sounding knock
- Thread starter dave
- Start date
gmjunkie
Corvette,GM Classic Freak
May be the the ZF transmission or Duel Mass fly wheel.there noted for being a little noisy!!:thumbsup:How smooth does it shift??My 94 was noisy and stiff as hell till I changed the trans with Royal Purple! Theres still a little noise but it shifts allot better!!:thumbsup:
With 90K it has a little slop and manual trans whine but shifts smoothly. I've read about the two piece fly wheel but they described it as more of a tap similar to a lifter. This doesn't sound anything like a lifter. (at least any lifter I've ever heard) It is a deeper hollow sounding knock. It maybe slightly more noticable from the passenger side of the engine. It is very hard to determind where it is coming from. With a stethescope I can't hear any knock at all from any part of the engine I can reach. As the engine warms up it fades away to the point you can't hear it at all. Plus....I don't know if it is something I should be concerned about anyway.
One by one I'm going to get all the bugs out of this car.
One by one I'm going to get all the bugs out of this car.
Scavanger
New member
My 90 had a knocking sound when cold. You would have sworn it was something broken.Was kind of a clacka clack sound.Really hard to describe. It was more of a double knock not like a lifter at all. I finally decided it was the transmission.
Over time my clutch started to slip. I finally replaced the clutch last summer. The knock is completely gone.
I am not so sure that it isn't the flywheel that was doing it. If you know how the flywheel and clutch works on these it is understandable. The engine runs just a little rough when coldas it warms up it runs smoother and the lash in the flywheel smooths out.
I ordered my clutch and flywheel from Carolina Clutch. I talked to them and asked a lot of questions. I was told that it is not unusual for the dual flywheel to wear out in 60,000 miles, and for one to go past 90,000 is unusual.
I don't know about that but mine apparently was worn out.
Scav.
:wavey:
BTW it runs smoother with the new flywheel and clutch.
Over time my clutch started to slip. I finally replaced the clutch last summer. The knock is completely gone.
I am not so sure that it isn't the flywheel that was doing it. If you know how the flywheel and clutch works on these it is understandable. The engine runs just a little rough when coldas it warms up it runs smoother and the lash in the flywheel smooths out.
I ordered my clutch and flywheel from Carolina Clutch. I talked to them and asked a lot of questions. I was told that it is not unusual for the dual flywheel to wear out in 60,000 miles, and for one to go past 90,000 is unusual.
I don't know about that but mine apparently was worn out.
Scav.
:wavey:
BTW it runs smoother with the new flywheel and clutch.
gmjunkie
Corvette,GM Classic Freak
Yeah Scav,thats what I'm think'n!!My 03 Z-51 has had a deep hollow knock sound since new,Kinda sounds like a thrust main knock in a Big Block or Piston Slap!!:thumbsup:Clears right up after about 1/2-3/4's way to running temperature!!:thumbsup::thumbsup::thumbsup: