Annoying engine knock

[Kamyoon]

I have a 2000 Sierra 4.8L with a 3 or 4 annoying issues that I have been living with for the past 50,000+ miles. I just got turned on this site today and have found a few good solutions for some the problems. The only one I have not found any answers to is the piston-slap or the engine knocking sound. My engine makes it all the time, but its worse at cold start in winter.

 

Some had posted various oil brands as remedy, and pointed to PTFE coating of the piston skirt as GM's stop-gap solution for this problem on the 2003 models. If teflon is what GM engineers think will work, even if it is short term, then why not something like Slick50 or Marvels Oil, etc. I have a couple of bottles of Slick50 left from a few years ago when I had an old Isuszu trooper that burned oil like crazy. It used to reduce oil consumption. You think it would work after 5 years of sitting in the garage, or even if it was new? Would it do any damage?

 

Any advice on this subject will be greatly appreciated.

[jhm]

If you are out of warranty, I assume you are with 50k, the best bet would be to contact GM and ask for an extended warranty as a good faith gesture. Trying oil supplements could do more damage. THEY CLAIM THIS KNOCK WILL NOT RUIN THE ENGINE BUT I HAVE SEEN SOME THAT WERE. I got 29k on mine and even though I don't have cold start knock, I am getting progressively worse high frequency noise on acceleration. Since I got the extended warranty I plan to run it into the ground, maybe it will grenade before the warranty runs out Good luck!!

[asepgrad98]

if it is knocking all the time it is not Cold start knock. have it looked at by a good mechanic.