8th Mar 2008, 12:40

I have a 2001 2500HD 6.0L that I bought with 30K miles on it. I was aware of the "knock" issue when I bought it and I heard a little when I test drove it. I figured I'd live with it. As time has gone by (has 55K on it now) it has gotten worse and really never completely goes away. I pull a 10K gooseneck with it and just let it run... I keep hoping it will blow up so I can put a new one in it. I've tried several oil additives and run 10W30 in it with no luck. Some mornings it won't do it at all until it comes off of fast idle, then it sounds like a lifter. Other times it is there right away and sounds like piston slap. Other than that it is a nice truck... embarrassing to start up with people around though. At 4000rpm pulling hills with the trailer on, you cringe waiting for it to come apart...

9th Mar 2008, 22:56

Suck some seafoam through a vacuum line to clean the carbon from the top of the pistons; it's not a lifter, it's pinging due to carbon build up on the pistons. I just did it and it worked great, no more knock.

27th Apr 2008, 19:29

I own an '02 Chevy Silverado K2500 and I have "the knock". I bought the truck from my brother in '06, and he bought it brand new in '02 or '03. At the time he was a certified ASE mechanic at a GM dealership. When he discovered this knocking noise at about 12000 miles, he took it to his service manager. GM extended a 3 year or 100,000 mile warranty, saying it wouldn't be a problem.

Now I own it, and it is burning 1.5 to 2 quarts of oil between oil changes, because of the piston slap. When the 3.4 motors had this problem, they replaced pistons. I took it to the dealership, with the letter stating the problem and warranty, and the dealership and GM avoided to address the problem of burning oil. They said that there was no oil leaking from the truck. They told me that if I wanted them to tear into the motor, that they would charge me for it. What good is a warranty if I have to pay? The knock is not a big deal to me, but adding oil every 1000 miles is. There is a problem, and we need to find a way to fix it for all of us Chevy fans who feel like we have been stabbed in the back.

There is another website about this problem, www.pistonslap.com. Maybe we will be heard, and GM will step up and do something about it.

18th May 2008, 22:56

I just got a 2001 Chevy 1500hd with the 6.0 and when I bought it I had no idea about the knocking. Now the noise is very clear on start up and on heavy acceleration. I am a diehard Chevy fan and have owned them all my life and never had a problem; now I am embarrassed to even own this truck. I run 5w30 Mobil and tried some restore and it helped for about 2 weeks; then took a camping trip and it came back. Don't know what to do, but I am angry.

27th May 2008, 21:02

Unfortunately I own a 04 GMC 2500HD. The knocking noise is there, but it is buried by the leaking exhaust manifolds. As a result of poor engineering, the manifold casting is far too slight and the manifold bolts are that small that they will actually snap off while driving. This is a regular occurrence while attempting to tow a trailer. The truck is rated at 10,000 lbs tow capacity, and my trailer is 6500lbs.

The GM dealer just advised me that the problem will only be cured if I modify the exhaust system. If anyone is considering buying one of these engines, check all facts, I wish I did.

15th Aug 2008, 20:59

I have a 03 1500hd with the 6.0 and it sounds like it's going to fly apart when cold. Sometimes it quits for just a second when you put it in neutral then back into drive, but then the knocking starts right back up. The truck has 103000 miles and seems to have good power and uses no oil. I took it into the dealer and they told me a lifter is shot and the cost would be 800 dollars and be only a temporary fix. I should buy a new motor for 5000 dollars. What a bunch of crap to spend that much on a truck that only books for around 13000!

5th Sep 2008, 16:13

I have a 2002, 2500 HD, crew cab, 4wheel drive.

I have never had the knocking problem that so many have made a comment about. However... the problem that I am having is that the truck dies for no reason while driving normally. Just shuts off like the key was turned off... After I turn the key off and wait for a few seconds, it starts right up and continues on with no problem.

I took it to a private mechanic that I trust and he could not find the problem.. he could not make it fail and he said the truck on board computer showed no failure codes. One comment that I have read, quoted the same problem with the dealer not knowing what to do... any help or comments...? Sep 6, 2002, Don.

1st Nov 2008, 11:17

I have the same knock in my 6.0; it's annoying because sometimes it sounds like valve-train noise, and sometimes it sounds like a rod knock. It's like a game; I get out and listen to it through the drivers side fender well because it's not coming from the passenger side or under the hood. With this knock and the transfer case pump rub, I am no longer a Chevy fan.

I have 130,00 miles on it and it has been taken care of with synthetic oil every 3,000 miles. I feel robbed. A Toyota with the kind of care that I have given this thing would run for a 500,000 miles with no problem.

10th Nov 2008, 18:39

I have been a die hard Chevy guy all my life. My whole family works for General Motors.

I just bought an 05 Silverado Z71 with the 5.3 engine. Runs great with no problem other than the constant knock at idle once it is warm. Very embarrassing.

I have held the thing on the rev limiter to try and blow it up... Won't blow. It runs mint and knock goes away right as soon as you get into the throttle??? What gives? I have no idea what it could be.

I have spun a lot of rod bearings in my time as I used to build and race early Camaros. It sounds like a rod knock for sure. Usually if it is a rod knock, it will re appear under load at certain rpms... Any info would be appreciated! mike@theautodreamgroup.com

21st Nov 2008, 15:58

I have a 2001 2500hd with the 6.0. it has 107,00 miles. I only have the knock when I start the truck in cold weather. from 32 degrees and below. it also uses about a quart of oil between oil changes which isn't that bad. I love the truck it drives great and pulls great I am hate the knock though. I hate to start the truck around people when its cold. everone notices it. if anyone knows a fix for this let us know.