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GM Engine Knock
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Comments
I've followed this discussion for months, and I was under the impression that they had fixed the problem in 2003 engines.
The TSB listed above specifically includes 2003 models. NOW I don't know if I should take the plunge.
Does anyone have a 2003 Chevy V-8 that has started making the noise?
Joe
Joe
http://gmpistonslap.tripod.com/
I believe I read a post about a 03 having the knock not long ago. So yes the knock is still an issue (annoyance) of some trucks, it's a toss of the dice whether yuou get one or not. All in all I still would buy another Chevy Truck cuz I'm partial to them but they need to resolve their production line problems with these engines.
Ray T.
Thanks,
dmadden
Ray T.
http://gmpistonslap.tripod.com/
If I had bought a truck that started knocking in 100-500 miles, I couldn't stand it. The dealer said he heard they are making significant changes on the 2004 engines. I'll wait and see.....
I'll wait til they get the bugs worked out of them.
Joe
-David
If I was a Chevy stockholder, I'd be extremely pi$$ed. Matter of fact, I'm extremely pi$$ed that Chevy won't be an option next year when I'm in the market. What the he11 are they thinking? A mistake here and there is understandable, but to continue to build these tapping nightmares with their collective heads buried firmly in the sand is inexcusable.
Ray T.
is ethics restored.
-David
If I were to trade the vehicle in, it would be up to the dealer to verify what he got. GM having known in advance about the "knockers" I'm sure would be cautious to take back a knocker or give you proper trade value although according to corporate the knocking is normal to them at the time we bought these slugs, that's a whole different story though.
Selling privately your best to remember the person could come back to haunt you, or worse yet he could have no ethics or values and come back to trash your car/truck/house for that matter if you rip him off !
I give credit to those sales people who do the right thing, it's not an easy living but by their own choosing. The dirtbag sales people get their just deserts in the end.
Ray T.
kip
Ray T.
All within 5k of expiration of the original fact...
thanks
I had a 97 GMC that sprung a leak at 102K. I personally did the intake myself and I don't think it was the Dextrol. On the vortec motors GM went to what they call a "Low Torque intake". In doing so, they us a gasket that is a composite with a rubber seal all around. This gasket is torqued in Inch Pounds unlike the older ones that are in Foot Lbs.
When I removed my gasket it was cracked by where it leaked. I don't think Dextrol could cause a crack.
Ray T.
Decarbonization has been proven to be a temporary fix for the knock. Only permanent cure is a new motor or pistons.....
I have a friend at GM powertrain and he said that GM is working to adjust the spec that caused them to use the piston design currently in use.
I would think that the whole engine line would be diferent for '04. Right now GM's trucks are underpowered compared to the new competition.
Ford, Nissan and Dodge all have 300 HP engines in 1/2 ton trucks for the upcoming year.
But the competition seems to be doing that for them already by having more H.P. then they do.
Ray T.
From: Truck Trend March/April 2003
TxDoc2
We’ve finally gotten an answer on the cold-start piston knock involving 4.8, 5.3, and 6.0-liter V-8s in ’99 to ’02 GM cars and trucks. General Motors has previously released a Technical Service Bulletin explaining the condition that occurs after approxomimately 12,000 miles.and a normal accumulation of carbon above the top piston ring.
I spoke with Sam Windgarden, GM program manager and chief engineer for small- and big-block engines. Sam explains that following extensive testing, General Motors is confident the start-up noise will have no adverse affect on performance or durability of the engines involved.
As opposed to the larger pistons of earlier design engines, today’s mechanical refinement requires the use of smaller pistons to reduce weight and reciprocating mass in order to aid in efficiency and durability. This reduction in size also reduces the stability of the piston in the cylinder bore, which can promote piston noise.
Preliminary testing on these engines showed no sign of a problem, by, as in many other situations, the symptoms came to suface after the vehicles were subject to normal-driving conditions. The manufacturer’s stand on the issue is that it doesn’t warrant a service bulletin or recall promoting a repair.
We were also assured the problem has been corrected on the ’03-model line with a piston-design modification along with the addition of a polymer coating.
My response was from a viewpoint of a consumer who purchased a brand-new vehicle that developed a notable engine knwfck before the first major service. The complaint was not only about the annoyance of a condition, but also the effect on resale and depreciation. The answer was that General Motors would be dealing with the consumer on a case-by-case basis, and complaints have been resolved by means of a warranty extension and parts replacement. The owners of involved vehicles exhibiting the cold-start piston knock should have the service manager of the GM dealership, which has been evaluating the noise, contact the manufacturer’s zone representative. Hopefully, you can come to satisfactory terms.
Ray T.
It has been 20 degrees and colder and my engine has been quiet (knock on wood)
It comes and goes like the wind
I found this new site that may have some valuable info for anyone interested.