6.0L warm start knock

December 17, 2003

I posted this on other forums as well. I have an 03 2500HD w/ the 6.0L. After the vehicle has warmed up and sat for about 10 or more minutes and then restarted it has a low end knock. First dealer couldn't figure it out. Did NOT call it CSK, couldn't as it is fine when started cold. While I was there he called GM & got a case # for it. This Friday I'm going to the dealer I bought it from so they can take a shot at it. Interested if anyone else has experienced this with their rig. Mine only has ~ 2,300 miles and I first noticed this around 1,500 miles BEFORE switching to Mobil 1.

Regards,

Jeff

cbz2500hd · December 19, 2003

Yea I have something similar. Mine (6.0 2500hd 2003) does it mostly at warm.Anytime between 1000 and 1500 rpm. Dealer is going to check it out.

fuelman · January 8, 2004

This is exactly why I joined this forum. I bought a 2002 reg. cab in August w/22k. Truck is decked out (lowered, wheels, system, blower, the works) and I hardly ever drive the dang thing,but I have just noticed the bottom end knock you described. Definitely not the CSK. I wouldn't sweat that, this is different. My first fear was a spun bearing, but there's no reason for that. I started it up tonight and went poking with a stethoscope and didn't hear much until it warmed up, then I got under and it got louder. Still runs great, but what the hell? Also found some more comments on this on rv.net. Any info!?

tuffchevy · January 8, 2004

I have a 03 Silverado 5.3 that has the same problem(9,000 mi). It does not knock at cold startup. If I park it some where for 20min to an hour and then start it back up it has what sounds like a low end knock that usually can last from 20sec to almost a minute some times. Going to the dealer next week to see what they say about it. If you have any luck with it keep it posted. Did it get better when you swithched to Mobil-1?

January 8, 2004

Unfortunately, the Mobil 1 did not make it better. GM asked that drive it until 5k and to monitor the frequency of it etc. Well now it is even louder when it happens. Initially, I had to be standing by the wheel wells but now 15 feet away and it makes a nice echo. For me, to add fuel to the fire, I went out to warm it up today and melt off some ice: check out the news for weather in Portland, OR and you'll know what I'm talking about. Lo and behold, the passenger side mirror defroster did not work. No CSK so that's a good thing! I don't want to come across as a baby to GM but I have had enough issue with this truck in 2 1/2 months to make some people go ballistic. I don't want it bought back, I want it right. And if they can't fix it then give me some Duramax emblems to put on the doors! If I do have to file for a lemon, then I want my new rig to have the same factory mods I've added to date. This is the reason I have not been to the Line-X dealer. That is something I can't take with me.

Jeff

cbz2500hd · February 1, 2004

I finally got fed up with the b.s. of it's normal. I contacted a lemon law lawyer. He said he would take my case no cost to me and in California the manufacturer pays the bill. When they write noise heard is normal, no fix at this time it really means your truck is not right we just don't know how to fix it. Anyways the lawyer said I would require two more dealer invoices so I took it to a different dealer. They dropped the pan to check if oil pickup tube is restricted. Changed an 0ring and it did not make any difference. They admit that the noise (warm start knock and constant knock at 1500 rpm when warm ) is not normal. Bringing back tomorrow

to let a gm rep listen to it and see what happens. That will be the fourth invoice and lawyer says it's a slam dunk case. I've requested to have my truck replaced.

Chris B.

February 1, 2004

Friday I called the Service manager to see if they had any updates on the TAN I was given and to let him know I was almost at 5000 miles and I'd be back in per their request. Issue has not gotten better but worse. I also have a nasty slap at ~ 1400-1500RPM each day whether is sat all night or a few hours. I tilt him I needed a couple Duramax badges for my doors. He said it would definitely be a quicker fix. He said he did receive a memo from GM regarding full replacement of ALL pistons but it was for the 6.0L only. I reminded him that is what I have and asked if it wouldn't just be cheaper to drop a new engine in. He said if the issues warrant it they probably would. Much less labor time on their end than pulling an engine and tearing it apart. Hopefully everything goes well. I've been holding off on getting my Line-X, installing my cap rails and other mods in the event that I have to work on them buying it back. I'll keep you posted.

Jeff

GM GIMP · February 2, 2004

My 2002, 6.0 has warm start issues. I haven't been to the dealer yet.

Right now I think I'd rather have the knock than let some Technician

still in diapers open my engine to replace pistons. I'd much rather

have a new engine.

shelbyd · February 3, 2004

My 01 Sierra 1500 with the 4.8 had the same problem. Replaced the o-ring, no change. Never could figure it out. I traded it in. They never even started it up when they looked it over at trade in time. So far a quiet 6.0 but it's early yet. 2000 miles.

cbz2500hd · February 4, 2004

Took my truck in for fourth invoice. They had a GM rep out to listen to my warm start knock and constant knock. The new diagnosis is wrist pin noise but don't worry it's normal. No matter where the noise is coming from don't worry it's normal. Don't let them b.s.you you all have wrist pin issues. Even the service advisor is honest he tells me my motor is fu.....

rad14u · February 9, 2004

I bought My 2500hd in 2001. i noticed the problem at first around 4-5 thousand miles, just thought it was due to the cooler weather here in phx,az. thought that it was a lubrcation problem at start up, didnt think much of it until another firefighter at work had told me that it was piston slap. the dealer told me "carbon buildup" and they documented it and sent me a 100,000 mile engine warranty.

well what i wanted to know was what caused the buildup in the first place? there's about a dozen guys on the job that have these types of trucks and we want solutions not excuses!

we all know that it's due to the sloppy play in the pistons that is causing the knocking, extra oil use, abnormal wear on cylinder walls and so on!

g.m. we want to know when you plan on taking care of our problems!! we trusted in you that your vehicles are some of the finest made. we've individually have spent 30,000 to 35,000 for the purchase of our trucks! thats alot of money in my book!!!! and for what? a truck thats "built with a knock" not built "like a rock"

g.m. we already know your buying them back, we already know your replacing engines, so do the right thing and take care of all of us!! you sold us a "lemon" and know it!