I have 2000 Silverado V-8 with 127K miles. Ever since it had 30K miles it has made what sounds like lifter noise on cold starts for about 20 secends. The GM service bulletin says it is carbon and nothing to worry about. My problem is that I want to sell the truck and no one is interested in buying it with the noise in spite of it being present for over 90K miles. Any ideas on how to quiet it down?
The noise you hear is probably piston slap which is a well known issue that the GM engines have.
This occurs on a cold engine where the piston skirt slaps the cylinder wall as the piston moves up the cylinder. Once the piston heats up the clearances between the piston and the cylinder closes up and the piston slap stops.
There’s nothing that can be done for piston slap other than rebuilding the engine with closer fitting pistons. And piston slap is not detrimental to the engine. It’s just embarrasing as hell when the engine is started cold.
Tester
My “silverado” is a bit older than yours, but I agree it is lifter noise.
Mine had it for about 10 or 15 seconds and ONLY on cold starts. My solution was adjusting the valves.
With the engine running and hot, back off each adjusting nut untill the rocker “clatters”, then tighten “SLOWLY” untill clatter stops, then turn an additional 3/4 turn. (I emphasize slowly because if you crank them down too fast the engine will run rough and possibly die) This will put the lifter plunger in the middle of it’s travel within the lifter. (You will need “lifter clips” to keep the hot engine oil from spraying on you and the exhaust.)
If this doesn’t cure it, then the springs in the lifter bodies are weak. You will need to isolate which lifter is still clattering (may be more than 1) and replace it/them.
If you don’t want to replace them, then just be honest with the buyers and tell them it needs lifters.
Thanks for the reply.
I sounds like a lifter and I’m having a hard time convincing prospective buyers there is nothing wrong in spite of showing them the service bulletins.