My 02 formula has a slight knock hot in gear idling. Sounds like bottom end to me and the lower the rpms the louder it is. The oil is spotless clean and the oil pressure is 45 hot idle 65 cold idle. If I slightly raise the rpms it just blends into the rest of the engine noise. When I 1st bought the car it had a knocking noise that came and went, very bad at times but i'm sure that was a stuck lifter from sitting for 5 years. The knocking i hear now sounds lower but in the same area of no2 cylinder.

I tried running it WOT and getting it hotter it seemed to be a little less noticable but its still there. I know its tough to nail LS1 engines noises down but i'm thinking on this one if it was a bearing it woooood get worse hotter and clatter as I blip the throttle, but it doesn't. I also noticed its really loud cold, this just started after I ran a bottle of Techron in the gas.

I'm going to try pulling the injector leads off one at a time to unload each cylinder to see if it changes but even if i find which cylinder it is I still won't know whats really going on.

Any good input woooood be helpful thanks.

 

Mine does the same. Cold its not there or very light. Hot its louder. Ive beat mine severely (turbo 6.0L) and its never failed. I am pulling it apart and replacing the engine though. It is kind of baffling what it could be. It sounds like a bearing, but isnt because it would have flew apart by now.

 

Is it an A4? Maybe a cracked flexplate??

 

id say if the noise does not get louder as rpm's rise and the oil looks fine, drive it! Ls1's are known to be noisy ****'s.

 

Yes it is a A4 but the noise is coming more towards the frt around number 2 cylinder. Thanks for the replies, at least its not uncommon.

 

If you can hear it over the exhaust.

OP, how many miles on it? Is the knocking coming from the pass side or driver's? You said #2, so that should be the pass side.. An odd place if it were an oiling issue.

 

78K on it and honestly i wooood have never noticed if i hadn't drove through Mcds.

 

I would start simple. Pull the valve covers, and check all the rockers and pushrods.