I have a 2000 Monte Carlo SS 3.8 and lately I have a knocking noise from top of the engine and there are days that the noise is gone. It sounds like a loose valve but I have no power loss and the car runs good except for the knocking noise, Does anybody know what could cause this ?

 

It's hard to say, if the noise sounds internal, 90% of the time it's cause of a bigger problem.

Does the noise go away as the car warms up?

 

sometimes it does other times it keeps knocking

 

check motor mounts. I've had two crack and had some bolts loosen up on another after dealer did some work and did not tighten them all the way I assume.

 

Tick or definite knock?

No check engine?

 

Good point, as would not a knocking sound activate the knock sensor causing a Check Engine Light with a P0327 or associated code . Where as a tick would not and it could just be a lifter problem..

 

its a ticking noise

 

no check engine light is on

 

A ticking noise could be an intermittently stuck lifter. This could be a simple easy fix fior you. Here is one link repairing sticky lifters, there are others just search about, they are all basically the same. Good luck, maybe others will chime in for you to.

Click on link below:

How to Get Rid of a Lifter Tick | eHow