A light intermittent knocking sound ???????????
Thread Starter
7th Gear
Joined: Nov 2007
Posts: 7
Likes: 0
A light intermittent knocking sound ???????????
I have a light knocking sound from the bottom side of engine area on a 1990 Vette. The sound only occurs after the engine fully warm up and only gets a little louder when the A/C is on . You have to pay attention in order to hear the light knock. The car drives and shifts fine with no problems. I brought to 2 mechanics and got 2 different opinions . One said is from the clutch bell housing and the clutch needs replacing. 2nd mechanic said it is the main bearings being worn and the crankshaft having too much play. I was wondering if anybody else has this problem or have an idea what's really the problem here. Let know me what you think.
Race Director
Joined: May 2006
Posts: 10,691
Likes: 71
From: Phoenix Arizona
I'm assuming you have a ZF 6spd. It's common for the dual mass flywheel to break down and cause that noise (ZF6's use a special dual mass flywheel because they tend to rattle). Or possibly someone has changed the dual mass flywheel out for an aluminum one. You might try searching for previous posts on this problem. It also could be your bearings, but generally that would be a rod bearing.
