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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).


  • ryanbabryanbab Posts: 7,240
    Ok i dont deny the "knock" shoot i have it at times (not all the time)

    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?

  • ricschricsch Posts: 540
    I have read where guys have put on quite a few miles, with engine knock and no trouble. Not to say it couldn't happen. This "problem" is being talked about on many forums and there are many thoughts of the cause, and the worst thing is that there doesn't seem to be a definate cure as of yet. I've been told by a GM service manager that they were instructed to replace engines in a few trucks with the knocking, and the new engines were worse. I currently only have 4200 miles on my '01 Silverado and haven't experienced the noise so far, but if it rears it's ugly head, I'll be the first to contact GM and the BBB. Curious to hear about the oil analysis.
  • jaguar0027jaguar0027 Posts: 387
    Ditto and well said my man!

  • I have a 98' 5.7 that knocks for about 5-10 seconds at first start. Started about 5,000 miles and now has 70,000 with no problems at all. I was told by a service rep that this was "spark knock".
  • Methinks it was a Tindy owner trying to raise a ruckus...
  • I just got my first oil analysis back at about 12000 miles, and it listed copper levels as critical. If my memory serves me right, copper is the top material on the tri-metal bearings used for the crank? So I am very concerned. I am hoping GM will do a short block replacement on these engines. But rumor is it will be new pistons only. I am sick to my stomach about this whole deal, as I really planned on keeping this truck for the long haul. But if GM screws us around I'll be trading for a Ford SD with the next generation Powerstroke next year.
  • ryanbabryanbab Posts: 7,240

    (i think the link will work)

    I have a kit coming in the mail soon

  • I used a kit I bought at:

    They were recomended by a couple guys over on the dieselpage.
  • I have a 00' 5.3 w/ 21k miles. The knock has been around since 3500 miles on cold starts. Dealer agreed to replace with a new engine which was just completed. Hope it works, repair order stated new pistons will not be ready until january 02' therefore gm agreed to replace entire engine.
  • ricschricsch Posts: 540
    keep us posted as to if the new engine develops the knocking. Thanks
  • We have an engine knock in our 2000 Silverado, engine is a 5.3. Chevy said they would
    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!
  • rayt2rayt2 Posts: 1,208
    then scan it and post for all to see so it can be copied and used by those in need of combating the GM......BS

    Ray T.
  • I have an '01 Chevy 2500HD LS EC SB 4X4 6.0/4.10 Auto. I now have a little over 7,500 miles on the truck. Just changed oil for the third time and rotated the tires. I have not had a single problem with this truck so far. No shudder/vibration, no hesitation, no knocking, just pure Chevy power (and I'm an old Ford guy). I do not use synthetic oil and have driven the truck pretty hard from day 1. I have averaged 13.2 mpg for the life of the truck (delivered 4/19/01). Hopefully, this will continue for several hundred thousand more miles. My previous two trucks were Ford 1/2 tons (both trucks had well over 200,000 miles on them when sold). Test drove the Ford 3/4 ton and the Chevy 3/4 ton. There was no comparison. I have installed a LINE-X bedliner (definitely recommend this liner to anyone). I plan on putting 16"x8" wheels and 285/75/16 mudders on as soon as I can convince the wife that it really does need new tires/wheels. My only complaints with this truck is the placement of the oil drain plug (empties all over the left side crossover pipe) and the 100 mph limiter (mine actually shuts down at about 97 mph). I did pick up a good trick from townhall for changing the oil. I tape a piece of aluminum foil over the crossover pipe - works great! I also picked up a pretty good trick from a buddy of mine so you don't make a big mess changing the oil filter (which is also an GM engineering snafu on placement). I poke a hole in the bottom of the filter with an ice pick (make sure you buy your own and don't use the one from the kitchen) and let the oil drain out before removing - this also works great! This is my first truck with an automatic transmission and may be the last. The automatic just can't figure out which gear my foot wants to be in - didn't have that problem with a stick. But, it is nice for backing the boat into the garage. Sorry for being so long-winded. God Bless to all!!!
  • obyoneobyone Posts: 8,054
    Way too funny,......nuff said.
  • seeligseelig Posts: 590
  • eric2001eric2001 Posts: 482
    taken a few out? Or they were removed by the author...
  • seeligseelig Posts: 590
    at first i thought the original post (you know, the one where post 1 says "BS" in full length) but then i figured an arguement broke out.....
  • obyoneobyone Posts: 8,054
    ....with no eggs. A troll with nothing else better to do.
  • y2kgmcy2kgmc Posts: 23
    I have a 2000 gmc sierra 4.8 which sounds like a diesel at idle , dealer first said it was because i was using too high an octane fuel and it was carbon buildup in the cylinders, and to switch to regular fuel and it might go away and if it didn't they would keep it overnight and soak it with a solvent to dissolve the carbon .well it didn't go away . a friend who happens to be a field service engineer with Saturn listened to it and said it was definately piston slap..
  • seeligseelig Posts: 590
    they all do that.....LOL....betcha heard that one already.
    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.
  • minikinminikin Posts: 389
    an octane fuel producing carbon build-up on a new engine!! Thought after all my years as a wrench I'd heard everything. Never under estimate stupid!
    -- Don
  • obyoneobyone Posts: 8,054
    to become Service Manager.....we already know its one to become a tech......stupid that is.
  • jlflemmonsjlflemmons Posts: 2,242
    Info - Engine Knock on Cold Start #01-06-01-022
    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.

    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.

    Deaf, Hearing Impaired, or Speech Impaired*


    8a.m. - 11p.m. (EST)

    8a.m. - 11p.m. (EST)


    8a.m. - 11p.m. (EST)

    8a.m. - 11p.m. (EST)





    7:30a.m. - 11:30p.m. (EST) (Mon-Fri)

    7:30a.m. - 6p.m. (EST) (Sat)

    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.
  • ricschricsch Posts: 540
    so now that the temps will be under 50 for another 3-4 months, I'll notice the "knock" in my 5.3, that's great!@##@ Can hardly wait to see the service? department, and their "Cannot duplicate" excuses.
  • ryanbabryanbab Posts: 7,240
    seems that mine is quieter in colder temps (5.3)

    it has been dipping below 50 quiet often here lately also. Supposed to snow by the end of the week
  • My 5.3 raps a bit on startup/no-load conditions. The funny thing is, my old Blazer did too. The 4.3L V6 had a nice rap, especially when cold. Now that it has 170,000 miles on the original motor, with good compression and power, I don't worry about the piston/head problem.

    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.
  • txyank1txyank1 Posts: 1,010
    I was under the impression that was just 6.0.
  • winkelwinkel Posts: 2
    As some of you might know, all metals expand and contract with hot and cold. GM is the #1 motor manufacturer in the world, and their motor boast more horsepower and torque than any other motor company in the world. To get the most out of their motors, they have to make the most out of the room they have to work with. there is only a 1000th of an inch in between the piston and the cylinder heads. Thus, when it is cold, the piston expands to fill up that 1000th of an inch, but when it warms up, the slap goes away. This problem is very rare. I work for a GM dealership in Reno Nevada, and have driven thousands of trucks and never heard any piston slap before. This is why GM isn't recalling any of their motors. there is a margin for error, not every piece that comes out of the mold is exactly the same. This is no excuse, but GM does back their products 100%. If you are dealing with a service department that is making poor excuses for GM, then you need to find a new service department or contact GM direct. Keep in mind, that the Service departments of GM dealerships are independently run. Although most of the service writers that work for the GM dealerships have had some sort of training, some have not. They are people too, and people make mistakes (and excuses). For all of you people that bought a GM truck and are thinking about going to another make, feel free. I don't mind all of the Fords and Dodges out on the road as long as they keep their under powered trucks out of my way. But don't let your local dealerships service department steer you the wrong way. There is way too many resources available on the net now days, so ask you questions to the right people. Good luck to all the people with problems, and remember that when you are #1, there will always be someone trying to drag you down...

    Nick Vanderville
    Internet Manager
    Winkel Pontiac GMC Hummer
    -Reno, Nevada-
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