Recently my 2003 Z06 started to make a knocking noise from under the hood and I'm having a hard time pinpointing it.
Long story short, the harmonic balancer failed and the car sat for 2 weeks while i collected parts/tools/research before tackling the job. Got it all buttoned up and started it for the first time in 2.5 weeks and was greeted with a very loud knocking noise that seem to be coming from cylinder 1 and 3. I used a stethoscope and the noise is definitely louder on the valve cover, than on the cylinder head at 1 and 3. . It was not doing this before replacing the balancer, so it seems odd to me that it would be rod knock. A collapsed lifter would make the most sense, however i dont feel the noise matches that diagnosis. I have pulled the valve covers and cranked the engine (fuel pump relay removed) to watch everything in the valve train. All appears to operate correctly and there is no noise at cranking speed. I have also tried pushing on the push rods to see if i could locate a collapsed lifter and none budge... I also pulled the push rods on 1 and 3 as that seems to be where the noise is most prominent but they look great. I think this is way to loud to be piston slap, but i have not let it run long enough to warm up as i do not want to cause any more damage. I don't think it is an exhaust leak as i have not messed with that system but i suppose anything is possible...?
There is no CEL, and there are no stored codes in the DIC
Does anyone have any suggestions to help isolate the issue before i tear anything down?
Thanks,
EZ
Last edited by ezstreet; Today at 11:35 PM.
Help pinpoint engine noise