GM ENGINE KNOCK
gmlemonowner1
Member Posts: 1
in Chevrolet
My 2001 truck was built with a 1999 engine that had been marked in a TSB for exchange. GM engines display a cold start knock located in the crankshaft main bearings. The knocking pounds the bearings to death. Eventually the engine will fail. GM is telling the dealers to tell the customer that this knocking is normal and that they built it into the engine([non-permissible content removed]). You can do an engine oil analysis on any knocking engine and it will show heavy wear(failure).
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But how do you know your 01 was built with a 99 engine?
TSB for an exchange?
When does the failure occur? I know a few people with 99's whos knocks and they have 80-100K miles and no problems. No performance losses.
Did you do an oil anaylsis? What were the results? (Actual) what was found in your oil?
Ryan
Jim
(i think the link will work)
I have a kit coming in the mail soon
www.avlube.com
They were recomended by a couple guys over on the dieselpage.
replace the engine but the pistons will not be out until first or second quarter of 2002.
They stated it will not be on a recall bases, but as a complaint bases. They said the pistons have 3000th gap... therefore wouldn't piston slap cause leak down in the cylinders? Of course!
The engine integrety has been compromised and were stuck with Chevys BS lines! NOT!
We DO HAVE IT IN WRITTING WHAT GM TOLD DEALERS WHAT TO SAY- THAT THE KNOCKING IS NORMAL. As I said, if it was normal - WHY are they so willing to drop an engine in... but what is the advantage if the pistons are the same and not the teflon coated ones. Chevy knows its a problem and were the idiots stuck w/ them until we jump the boarder and buy another brand! God Bless Us ALL!
Ray T.
do like a lot of us have done and file with the BBB. it resulted in an extended warranty (courtesy of GM) for quite a few who have this problem.
-- Don
Information on Engine Knock on Cold Start
2001-2002 Chevrolet and GMC C/K Pickup and Utility Models
with 6.0L Engine (VIN U -- RPO LQ4)
Some of the above vehicles may exhibit an engine knock noise that begins in the first several thousand miles/kilometers of use. The knock noise is most often noticed during initial start-up and typically disappears as the engine warms up. The noise is usually more noticeable on the initial start-up when the temperature is below 10°C (50°F) or if the vehicle has not been used for several days.
This noise may be caused by an interaction between the piston and the cylinder wall. GM Powertrain Engineering, and an analysis of engines returned with this condition, has confirmed that the noise is not detrimental to the performance, reliability or durability of the engine. The noise does not have any effect on the longevity of any of the engine components.
Important
At this time, replacing the engine assembly or pistons will not eliminate this noise.
Please share the information found in this bulletin with customers who inquire about this condition. In the event they have additional questions or concerns, please advise them to contact Customer Assistance at the numbers listed below for further information.
Division
Number
Deaf, Hearing Impaired, or Speech Impaired*
Chevrolet
1-800-222-1020
8a.m. - 11p.m. (EST)
1-800-833-2438
8a.m. - 11p.m. (EST)
GMC
1-800-462-8782
8a.m. - 11p.m. (EST)
1-800-462-8583
8a.m. - 11p.m. (EST)
Canada
1-800-263-3777
(English)
1-800-263-7854
(French)
7:30a.m. - 11:30p.m. (EST) (Mon-Fri)
7:30a.m. - 6p.m. (EST) (Sat)
1-800-263-3830
7:30a.m. - 11:30p.m. (EST) (Mon-Fri)
7:30a.m. - 6p.m. (EST) (Sat)
* Utilizes Telecommunication Devices for the Deaf/Text Telephones (TDD/TTY)
© Copyright General Motors Corporation. All Rights Reserved.
it has been dipping below 50 quiet often here lately also. Supposed to snow by the end of the week
I do notice that the sound is a little different...but I think that is because the Blazer had iron heads and the 'rado has aluminum heads. They make different sounds when you slap an aluminum piston into them.
I'm sure its a GM powertrain, piston clearance spec that is a little tighter than most. For emmissions no doubt. I've heard the small V-6 (2.8, 3.1, 3.4L) derivitives and the Buick V-6 make the same noise. Once the engine starts to warm up, the cylinder length grows a few mils, and the contact goes away.
Nick Vanderville
Internet Manager
Winkel Pontiac GMC Hummer
-Reno, Nevada-
Thanks for the help
The Chevy motors will run forever. Just feed 'em clean oil and let em slap. They will slap for 250 000 miles without an overhaul.
I did drive an identical 2001 Yukon 5.3 (non-ethanol capable engine) about a year ago and the engine vibrated so bad you could see the steering wheel shake at idle - even with the transmission in Park.
Does anybody know what the difference is between the new ethanol capable 5.3 and the non-ethanol capable vehicle? Maybe more hardened valve seats? Should I invest in corn futures? ;0)
2. All the newer LS1 engines have aluminum heads. The 4.8L and 5.3L have had them from the start. The 6.0L got em in 2001.
3. The knock you are hearing is most likely either:
a)piston slap, that's where the piston rocks back and forth on the end of the rod, and the piston skirt taps against the cylinder till it warms up.
b) lifter tap, where the hydraulic lifter is pumping up to take up the clearance between the valve and the rocker arm.
c) maybe light rod knock in the bottom end, where the big end rod bearing clearance is a tad large, GM supposedly tightened this clearance up for 2001.
d) maybe ping, I got this under load on 87 octane on both my 4.8L and my 6.0L. 91 octane would alleviate it
e) manual transfer case shift linkage rattle. Both my 4.8L and my 6.0L did/does it. Just gotta put a little washer on the linkage ball joint.
the cold knock. Having read all the posts, I took
it in for a oil change at the Chev dealer and had
him listen to it. He told me that GM was only going to change the pistons for the 4.8 and 5.3L.
I called GM and started a file and they quoted the
GM standard of "its not a problem". I,m now waiting on the Service manager to get with the
District rep and get his comments.
My plan is to go the BBB route just to be on the
safe side if I get no recourse from the Rep.
And to Nick in Reno, water is the only thing that expands when it's cold, everything else contracts when cold, and expands when hot.
They are fully aware of this problem but try to say it's normal. I showed him this page from this brochure http://agmlemon.freeservers.com/2001_Engine.htm
The service manager said that it di NOT come from GM. Does anyone have a link to the entire brochure? I think if I have that it will change their minds.
I also said something about the pinging and rough idle. He showed me a bulletin on the pinging from GM that of course, says it's normal. Yeah right.
Had them check the ABS brakes. If I am stopping somewhere and there are bumps in the road, it triggers the ABS and I end up stopping farther then I wanted, like in the middle of a intersection. Was told there would maybe a new software update soon. Sounds like more BS to me.
then engines don't need rings then eh?
LOL
http://209.61.155.43/moframes/division/gmc/products/GMC_features_48LR4LM7.html
Clay
How does anyone know it is a problem? Many engines have this, the toyota 4.7 has been known to do this (I seen posts on the toyota posts saying they hear a sound like this), it is really not out of the ordinary.
I would say were not going to know either way till these trucks are much older. But I have not heard of anybody with high oil consumption which would be what would result if this was a true problem.