knock at idle, annoyed!
knock at idle, annoyed! My 2000 sierra 6.0 has 187,550 miles on it. It's currently knocking at idle, warm and cold. If it sits for a week it doesn't do it. Under normal throttle it doesn't do it and seems to drive fine. It does need a water pump replaced. I don't understand if it's piston slap or a rod or main bearing, it goes away when driving though. I thought rod or main bearings you'd be able to hear even when revved up, or a vibration? Has a pulley ever been known to cause a knocking noise? The other thing I was thinking is maybe my tune? It's stock with a westers 89 octane tune, I don't understand how that could cause knick at idle and not under a load though.
I bought a 5.3 to go in but part of me thinks maybe the 6.0 is fine and it's something else not internal. No idea if people get piston slap when warm either.
I bought a 5.3 to go in but part of me thinks maybe the 6.0 is fine and it's something else not internal. No idea if people get piston slap when warm either.
I only get piston slap in my truck when cold, goes away after about a minute. Check your exhaust manifold bolts. I had a couple snapped on the driver side, gave me an intermittent knocking sound that almost sounded like rod knock.
Teching In
Joined: Aug 2018
Posts: 2
Likes: 0
TECH Addict
Joined: Mar 2013
Posts: 2,628
Likes: 30
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo Are you trolling or something? There are quite a few GM TSB's that mention the problem of cold start knock, or piston slap, especially for the 99-02 trucks. It's been documented by tons of owners over many years.
TECH Addict
Joined: Mar 2013
Posts: 2,628
Likes: 30
No not trolling just saying that TSB is complete BS............. real piston slap doesn't go away. GM is bullsheeting its buyers into accepting something else other than whats really going on. If you had loose slapping pistons the engine would be noisy all the time. Cold piston noise is normal in any engine, but its not slap or knock. If its knocking it something other than the pistons. Argue all you want, was just pointing out real piston slap doesn't go away.
Right, I'll just take your word for it then. We'll just ignore GM because they lie, because you said so, not to mention that piston slap when cold is well understood and not unique to GM vehicles.