New to the forum...did some searching but didn't find anything that sounded just like my problem.

My 2002 Xtreme Blazer overheated pretty bad and I hadn't noticed until it was too late. So I cracked the head. Replaced the head and now I've noticed a knocking noise at idle through 1500 rpms or so and it seems to disappear.

At first we believed it to be a lifter problem and now they have been replaced. No change in noise at all. Not sure where to even start as most mentions of knocking problems seem to always include different symptoms than mine. I've put too much money in it at this point so depending on what it ends up being..I may end up driving it until it just dies. Any help would be greatly appreciated.

 

Check your pushrods and see if one of them is bent. Just a slight bend could hang it up. Only true way is to take each one out and roll it on the table. That would be my guess, since lifters where done.