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GM Engine Knock

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Comments

  • PAmanPAman Member Posts: 207
    I was considering trading in my 2000 Chevy S-10 with a smooth 4.3 V-6 for a 2003 Silverado.

    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
  • PAmanPAman Member Posts: 207
    I meant to ask about the 4.8 or 6.0 engines.....

    Joe
  • rayt2rayt2 Member Posts: 1,208
    Try here for latest info if you haven't already.

    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.

  • dmaddz71dmaddz71 Member Posts: 14
    I drive a '99 sierra z71 and I bought it used. It has knocked ever since i bought it (now w/ 48000 mi.). It only knocks/ticks for a few seconds upon cold start. I think this is because their is no oil in the valves after sitting all night. But the main knock is in overdrive at 40-50 mph. At this time it sounds like it is running sick. I can control the noise by increasing throttle which causes the noise. Premium fuel has not helped I guess I am about to try switching oils as it is about due for an oil change, any suggestions? Mobil 1 syntheyic? please give me some feedback concerning this.
    Thanks,
    dmadden
  • obyoneobyone Member Posts: 7,841
    On the next occurance of your ping try downshifting to 3. I think your problem will disappear. Seems like your truck is straining in the wrong gear. The dealer can reprogram your trans to have it downshift a little sooner to get rid of most of the ping.
  • rayt2rayt2 Member Posts: 1,208
    Remember you changed to a larger tire size which in effect lowered your gear ratio. This will effect a few things along the lines of how it responds. The engine knock.....live with it like alot of us do and visit the website I posted about, alot of info on the knock issue there. The pinging could be related to a bad anit-knock sensor, your timing is off, the larger tires or combination of all. Either buy a HP3 Programmer and make your changes for the bigger tires and trans shift points or have a dealer do it for you.

    Ray T.
  • dmaddz71dmaddz71 Member Posts: 14
    what is that site?
  • rayt2rayt2 Member Posts: 1,208
    You only had to scroll back to post 269 to get there! Come on man get with the program !!! Here's the site again,


    http://gmpistonslap.tripod.com/

  • PAmanPAman Member Posts: 207
    Even with my GM discount, $1,600 earnings on my GM card, $500 dealer cash thrown in and a $3,250 rebate for GM buyers, I didn't take the plunge.

    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
  • twinscrewtwinscrew Member Posts: 53
    Do the dealers ignore big knockers (they've always been hard to ignore for me) or do they tell you that your knocker is worth less because of possible engine problems? Bet those negotiations could get interesting when GM has been telling you that the knockers aren't a problem until they are about to own and then try to resell one. If you try to sell the knocker yourself, what do you tell the potential buyer when he hears it? I've been driving chevys since '75, but switched to Dodge in '00. Can't believe they haven't fixed this issue yet.
  • noobie1noobie1 Member Posts: 326
    To me you raise the more important issue. As Chevrolet claims, durability may indeed not be affected. But, how much value is lost by that noise? Would an informed buyer buy a vehicle that sounded like that without a significant discount? Has anyone out there tried to sell one of these things?

    -David
  • twinscrewtwinscrew Member Posts: 53
    Personally, I wouldn't buy one that had even the potential to knock. That's the main reason I switched to Dodge. One that already has an audible knock has got to be tough to get rid of. How long can Chevy continue to build these things before their last buyer has one?

    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.
  • txyank1txyank1 Member Posts: 1,010
    just make sure the engine is well warmed up before anyone looks at it. (or hears it run)
  • joe3891joe3891 Member Posts: 759
    that GM sold a record 2.9 million trucks in 02.
  • twinscrewtwinscrew Member Posts: 53
    Guess I wouldn't have a problem doing that at a GM dealer, but selling direct to an individual would be a little tougher. When "Joe Average", his wife, and 2.25 kids comes to your house to look at your truck, are you not going to tell him everything that you know about your truck?
  • rayt2rayt2 Member Posts: 1,208
    to sell my knocker I'll be sure to let the buyer know the histroy and if I off it before 100k I'll transfer the 7yr/100k ESP I have on the truck as part of the deal. To not tell a private buyer is not an option, I like to think I was raised with good moral & ethical values, to do otherwise just makes you as bad as a sleezy car saleman, and remember the guy who you don't tell knows where you live !

    Ray T.
  • noobie1noobie1 Member Posts: 326
    Well said. Too much in the world already. We got here by increments and by increments
    is ethics restored.

    -David
  • txyank1txyank1 Member Posts: 1,010
    I can tell you I was lied to by Customers on many occasions. And BTW, I discovered you can't make a living as an honest Car Salesman.
  • rayt2rayt2 Member Posts: 1,208
    exactly my point, more and more people in this world have NO morale values anymore.
    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.
  • kg11kg11 Member Posts: 530
    with trading it in at the dealer I bought it from is I'd hafta get another GMC.If I get 100k out of it I'll be disappointed not to collect on the warranty.I don't expect it to be worth much when I'm done with it.

    kip
  • rayt2rayt2 Member Posts: 1,208
    Agreed, but I bought the ESP because I know GM reliability is lacking in other areas that will surely have me using the policy before I get rid of truck. The engine component warranty GM gave me for my knocker I don't expect to use but tranny, steering linkage/shaft & ABS system may be a different story before 100k.

    Ray T.
  • obyoneobyone Member Posts: 7,841
    So far I've used the extended warranty to repair my A/C and replace a leaking rack and pinion AND that was within 6 months of the end of the factory warranty.
  • gator36gator36 Member Posts: 294
    So far after original factory expired. I have used my GMPP for a bad fuel injector, faulty heated side mirror and fix steering clunk...

    All within 5k of expiration of the original fact...
  • dmaddz71dmaddz71 Member Posts: 14
    upon starting my truck, it seems as if the starter is not hitting the flywheel properly and a sort of grinding noise is heard. What could be a possible solution to this problem. This only happens about twice a week. '97 chevy 350cid
    thanks
  • twinscrewtwinscrew Member Posts: 53
    I've had the starter work it's way loose on several chevys. If it's not loose you'd better pull it off and take a look. If it continues to do this, it will only get worse. Best case...starter repair. Worst case...flywheel and starter repair.
  • themailman1themailman1 Member Posts: 95
    I deliver mail to a couple of gas stations and the word is out about intake gaskets being eaten up by the dextrol anti freeze. [pink stuff] They said it is garbage and to replace it with Prestone. The truck I saw was a 1999 Chevy with the 5.7 with 35,000 miles. Has anyone else heard of this?
  • jackleopardjackleopard Member Posts: 1
    At 52,000 miles my 1999 Suburban had problem with intake gaskets being eaten by dex trol. Mr. Goodwrench told me Dextrol caused the problem, because it had not been changed out. I asked him what happened to the claims of this great new anti-freeze lasting up to 5 years or 150,00 miles. He said it is best to change your anti-freeeze every two years no matter the type. I wish GM would not embellish what their products are capable of doing. I threatened to contact GM with a complaint, but I did not do it. The dealer , who has been good to me for several years, did deduct $150 off off of the $600 bill.
  • gator36gator36 Member Posts: 294
    Some should remember that Smallblock Chevy's have had leaks at their intake gaskets for years. This is a known issue that many engine rebuilders are aware of. They leak at either the front or rear passage over time.
    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.
  • rayt2rayt2 Member Posts: 1,208
    I'd have to agree with you on this one. I have never known anti freeze to cause problems with gaskets, overtorquing the heads/intakes etc will cause more problems over time. Antifreeze is just like water it seeks out the weak points, on small leaks I have had great results usng the same product the manufacturers use during assembly, Bars Leak I believe the product is called.

    Ray T.
  • dmaddz71dmaddz71 Member Posts: 14
    I saw an aftermarket engine additive that has set out to de-carbonize engines thus reducing the knock, it's called z-max and it sells for around $50. Has anyone tried this?
  • obyoneobyone Member Posts: 7,841
    I saw it at checkers. Do the same people make that Marvel Mystery Oil?

    Decarbonization has been proven to be a temporary fix for the knock. Only permanent cure is a new motor or pistons.....
  • lspangler1lspangler1 Member Posts: 68
    For those of you with engines that knock, I'm wondering how you use the truck. All engines tend to carbon up if not worked hard once in a while. THis can be as little as running the truck to redline in first gear once or twice per tank of gas or towing occasionally.

    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.
  • rayt2rayt2 Member Posts: 1,208
    Type of use makes NO difference with the knocking GM just tried to dupe owners into thinking it was a carbon issue, charge you for "maintenance" (deacrboning) as they called it and send you on your way only to have it reappear again down the road in 4 or 5k. I have had the problem since 16k (presently 38k)and will not let them even think about decarboning based on my theory, if it's carbon build-up then their computer settings are wrong and causing me to use more gas. I tow a 6600# trailer during summer and the engine gets a nice hard workout during this use, engine still knocks on start-up no matter what. In fact it's a manufactoring issue that will cost much more than an engine head soak, maybe that's what GM reps need to do is soak their heads and wake up !
    But the competition seems to be doing that for them already by having more H.P. then they do.

    Ray T.
  • themailman1themailman1 Member Posts: 95
    I broke down and used the full synthetic oil and my engine knock went away. We have had 0 degree temps and still no knock. I have a 01 Sierra ,5.3.16,000. Either I am going deaf or It worked.
  • ryanbabryanbab Member Posts: 7,240
    GM Piston-Knock Update
    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.
  • rayt2rayt2 Member Posts: 1,208
    So where's the latest update news?? that's the same smoke and mirrors GM is telling everyone, does Truck Trend get funding from GM. LOL !

    Ray T.
  • ryanbabryanbab Member Posts: 7,240
    That info came from someone else from another site. Dont shoot the messenger.

    It has been 20 degrees and colder and my engine has been quiet (knock on wood)

    It comes and goes like the wind
  • skid3skid3 Member Posts: 11
    January 2002 I replaced radiator and new water pump, not rebuilt on an 89 pickup. I flushed the system and decided to use Dextrol. The new water pump leaked antifreeze and I soon replaced it with another which also soon began to leak. For the third new water pump I flushed and replaced with regular green Prestone. No more leak to date. This came to mind when I read your post.
  • jtt3jtt3 Member Posts: 20
    It looks like a lot of people are having problems with GM pistonslap.

      I found this new site that may have some valuable info for anyone interested.
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