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6.0 liter knock

silverado6silverado6 Posts: 3
edited March 2014 in Chevrolet
I was just curious who has the infamous "normal" 6.0 liter engine knock? My 6 liter knocks like crazy for up to 15 minutes after start up. It will also knock after the truck has been sitting for a half an hour, so it is not really a cold engine knock. I have about 6,700 miles on this engine and this is the second engine in my 2000 Silverado. GM replaced the original engine at 15,900 miles for the same reasons (knocking and tapping). I would like to show GM that there is alot of other people that have the same concern that I do. I don't feel that I should have to turn up the radio to block out the noises when you have paid over $32,000 for a new truck.


  • jwhaelen1jwhaelen1 Posts: 27
    Silverado6, Maybe these two popular individuals can help out by letting you know how many others have your exact same problem,along w/ a solution. Here's their fun(ny) & informative site: You've probably heard them on the radio before. Good luck!
  • wight1wight1 Posts: 218
    It sounds like you have some serious problem if its knocking for 15 minutes. Mine knocks for maybe 10 to 15 seconds and then quits. Mine occasionally knocks when its hot, but not very often - its just the first start of the day or after its been sitting for a few hours. I currently have 24,000 miles on my 2000. The dealer did the top engine soak back at 22,000 miles and the knock completely disappeared for about 300 miles and then came back. I plan to seek an extended warranty, but I really don't want to swap out engines because I don't think they have the problem solved yet - even the latest 2001 models are knocking.
  • sf0383sf0383 Posts: 204
    Mechanic buddy of mine said he solved his knock with some kind of engine additive that keeps the top end lubricated when sitting. I'll try it at next oil change and let ya'll know
  • akjbmwakjbmw Posts: 231
    There are starting to be accessories that are designed to use stored pressure or an electric pump to get oil into the upper end of your engine before you start it. I saw either Trucks or Crank & Chrome do a review/install on TNN a Saturday or two ago.
    If the problem is oil not staying up where it should be, this might help. If it is slop in the fitting of parts, it might require a serious heater to get the engine up to operating temp before starting it. ;-)
  • gumpymacgumpymac Posts: 4
    I have a 2001 2500HD with 6.0 and was curious about the noisy engine, sounds like a light thrashing or rattling, seems to be there *always removed the plastic cover from above the throttle body and used a long screwdriver (as you would a stethoscope), to listen to all of the engine components. The noise comes from the two fuel rails that run fore and aft on each side, the injectors and a crossover tube in the middle, no noise at the valve covers,intake,heads or block. 3500 miles, no other eng. problems.
  • nerdnerd Posts: 203
    I have a 2000 Sierra 1500 with the 5.3L engine, and I am having the same symptoms. At about 9000 miles, it developed a knock (sounded like a lifter) when cold. The dealer did a GM-recommended "decarbon treatment" which did no good. The truck now has 15,000 miles and the knock is getting worse - even happens some when the engine is warm. The dealer's shop foreman told me yesterday that GM now says that many of these engines (the 5.3 and 6.0) have bad pistons without adequate skirts. He said that GM has redesigned the pistons and will install them in engines in response to customer complaints. GM customer service told me the same thing, and they have entered a case number for me. I am not too happy about having a dealer tear into the engine. I am wondering if anyone else has gotten this story.
  • I just brought in my 2001 2500 ID for the initial oil change at 2800 miles. The engine has been knocking on cold starts and warm re starts since day 1. The service manager says he knows what it might be, but mums the word until he talks to or Em-ails his district re. They de-carbed the engine (yes at 2800 miles) it runs O.K. except for some low gear, light throttle engine skip. If I get an answer I'll let ay know.
  • whatsachevywhatsachevy Posts: 136
    '01 Chevy 2500HD 4x4 EC SB 6.0/4.10 Auto - 3950 miles - just changed oil for the second time. Forgot just how fun that was. I can't figure out how any engineer could have located the oil drain plug and the oil filter in front of the exhaust pipe and crossmembers. That is my only complaint with this truck. I have not had a single problem with this truck so far. No rattles, knocks, engine-skipping - nothing. I have driven the truck pretty hard since day one (including finding the engine shut-off speed several times during the break-in period). I'm not used to having this kind of power. I have averaged 13.4 mpg overall (lowest 12.2, highest 14.9). I have no intentions of using synthetic oil now or in the future. My last two vehicles had well over 200,000 miles on them when I sold them. All I have ever used is Motorcraft (yea, in a Chevy) 10w30. Anything else is just wasting good beer money.
  • bobsquatchbobsquatch Posts: 136
    There is a special hell for the engineers who thought up things like exhaust pipes under trannies and drain plugs aimed at the suspension and spin on filters mounted upside down. Hopefulley they will be damned to perpetually servicing their own creations (while extremely hot) cursing themselves all the while.
  • justomjustom Posts: 1

    I have a 2000 Silverado 1500 with the 5.3L engine, and it has the same symptoms as you discribed in your message. The dealer is telling me that they (CM) will have a new piston which will correct the problem, but that it won't be out until December. Is that what you are hearing also?
  • sonjaabsonjaab Posts: 1,057
    Hey thanks for the tip on the fuel rail noise.
    Sounded like a lifter to me in my 01 6.0.
    My bud has one of those stethoscope (spl)
    things. It worked great..............Geo
  • minikinminikin Posts: 389
    exhaust pipes under oil drain plugs and side mounted filters for sadistic amusement. Also usually try to figure out how to put other parts in the way to disperse the oil flow so you can't get around it. Used to to do the same sort of thing with big motor/small chassis muscle car spark plugs so you had to take the engine out to change the plugs every few thousand miles until the marketing guys made us stop it. It annoyed me when the car guys came up with the solution of drilling through the inner fender panel to get at that rear plug in the V-8 Vega's. Really spoiled the fun.
    -- Don
  • rayt2rayt2 Posts: 1,208
    Were you also on the design team for Ford when they built the Boss 429's back in late 60's? Where you have to remove the tire to get to the rear plug ?? Thank god I never owned one of them I stuck with the underdog and bought a 69 AMX with their big block, owned that bad boy for 30 years now and it's finally getting restored.
    Oh and regarding your engineering as bobsquatch stated.... That special hell awaits you! LOL

    Ray T.
  • nerdnerd Posts: 203
    Yes, I got the same story. The shop foreman listened to the knock himself and diagnosed the problem as piston slap. He said that GM is planning to replace the pistons along with new rings, connecting rods, and connecting rod bearings. I am not too excited about having a dealer rebuild the engine, so I plan to complain to customer service (they have issued a file number on my case). I would much prefer to get a factory engine, but GM's warranty gives them the right to rebuild it. Anyway, I will seek an extended warranty if they rebuild it.

    By the way, my son-in-law has a '99 Sierra with the 5.3L that knocks worse than mine. It has 80K miles without any problems...and he drives it rough.

    Let us know how your case goes.
  • ryanbabryanbab Posts: 7,240
    "It has 80K miles without any problems"

    So why not leave yours alone?

    "if it aint broke dont fix it"
  • modvptnlmodvptnl Posts: 1,352
    I (almost) understand where you're coming from with your comments but it really only shows blind brand loyalty and nothing else. When people pay $30,000+ for a vehicle they expect it not to make funny mechanical noises. Are you trying to say if your truck did this on a test drive you would buy it anyway????

    When your buds used to flame Fords for the piston slap in the '99 5.4's I didn't see the same stand.
    BTW, Ford replaced motors, not just pistons if I remember correctly.

    You should tell Oby to just accept any vibrations because it's really not affecting the longevity of the truck.....just really a nuisance, that's all. Why get the clunking intermediate shaft fixed??? It's just a noise. LOL!!!
  • ryanbabryanbab Posts: 7,240
    To respond to your question: Are you trying to say if your truck did this on a test drive you would buy it anyway????

    If i knew it didnt affect the trucks performance, reliability, or anything else yes i would.

    It seems many trucks like the example above with 80K have it with no ill effects just a cold start knock which goes away. If it knocks all the time (isnt that the case with the F150s? im not to familiar) thats a problem then but if it goes away within a few seconds i wouldnt worry about it.

    MOD you have to agree with me a little on this too. Alot of people complain about vibs who have never driven a pickup. They arent used to how a truck drives.

    Why get the steering shaft replaced? Well because it was loose? Possible safety hazard? I know after mine was changed the steering was very improved.

  • Siverado6

    After soaking the pistons, decarb, checking purge and cannister system and balance test. The conclusion by the dealears service dept. is that the engine noise is the same and increases slightly with RPM. The service Mngr., after discussing my problem with his district service rep., has told me that some 6.0 engines have pistons that are out of tolerance. New pistons will not be available until sometime in 2002. Current production of the 6.0 use the same pistons, so changing the engine now may result in better, the same or worse results. Since performence is O.K. and I don't do more than 6K a year, I'm going to wait and see what happens, but as a lifetime Chevy man I'm not very happy right now.
  • modvptnlmodvptnl Posts: 1,352
    The Fords only did it on start up also.. And while trying not to be rude,(I swear) If you buy a truck or car or anything that makes a NOT-NORMAL mechanical noise at the time of purchase when there are many other choices without this potential flaw, then you, my young friend, are what I call blind brand loyal.

    My buddy drove his GMC with clunking steering shaft for 10,000 miles, there's no safety issue or it would have been federally recalled. IT WAS JUST ANNOYING and unacceptable for a vehicle, truck or not. Much like an engine knock regardless of brand.

    So Oby is just being too picky about the vibes on his truck???

    While you may not want to accept it, the fact that something is knocking when cold means those clearances are looser than where they should be(Ford was running forged pistons which naturally must be run with more clearance than a cast piston. There was just too much clearance)This may not affect performance at first, it will most definitely affect longevity. The motors are still wearing, they just have that much less clearance to wear out till you lose oil pressure or have a more permanent LOUDER knock.

    Sorry Ryan, any knock in a motor is unacceptable. Ford, Chevy or even (gulp!!) Toyota.
  • ryanbabryanbab Posts: 7,240
    I get where your coming from but what about these trucks with 80K miles 50K miles 90K miles and they are out there with ZERO problems. These engines arent falling apart. So far i do not see any longevity problems

    I didnt buy my truck with a start up noise. At about 10-11K it started. Doesnt do it everyday. Lasts about 5 seconds max.
  • modvptnlmodvptnl Posts: 1,352
    Looking at "the big picture" do really think 90,000 miles is a lot??? I don't think they are going to fall apart. But I have a suspicious feeling that they are not going to go the 200-300K that Toy, old 350's and Ford owners brag about. LOL!!!!
  • quadrunner500quadrunner500 Posts: 2,728
    I think they will.
  • modvptnlmodvptnl Posts: 1,352
    Time will tell. But if they had a fix for it, would you not accept it???

    Quad, I'm hurt!!! You ALWAYS agree with me! LOL!!!
  • minikinminikin Posts: 389
    Took about an hour plus to change just the #2 plug on my '69 428 Mustang; the rest of them took 10 minutes total. At least I think I remember it as being the #2 plug, 2nd back on the drivers side . Right up against the coil/shock tower and you had to work it out a little bit at a time with the tips of your fingers after breaking it loose with a plug wrench. And you had to grind away a good bunch of the plug wrench so you could work it onto the plug. That was after you carefully worked the plug wire/boot off. And you always broke the insulator getting the plug loose so you could never just give up and go back. And if you weren't really careful, you could crack the insulator on the new plug torqueing it down and have to start all over. And, unlike the Vegas where you could just drill through the sheet metal inner fender panel, to get at this one that way you would have had to dissemble the left front suspension and then drill through welds on the two piece spring tower. I've always admired the guy who came up with that one!!!
    -- Don
  • quadrunner500quadrunner500 Posts: 2,728
    I didn't have the problem on my '99, 42,000 miles so I remain a bit skeptical about how bad it can really be, or pervasive. Unless they changed the piston in 2000-2001. The complaint I had was about spark ping. On THAT point, Chevy/GMC is totally pig headed with the ridiculous overnight solvent soak solution, which contaminates the oil by the way. Maybe that's where the knock starts? I digress. They could have solved the pinging with about 5 degrees less spark advance, but noooo....
    Anyway, my solution for that was to modify the thermostat to open 10-12 degrees sooner. Worked in cooler weather, allowing me to run regular unleaded. In hot weather, t-stat is open all the way anyway, so no benefit. Ran premium for 2-3 hottest summer months. problem with DURAMAX diesel!!!

    I always agree with you when you are right!!!
  • modvptnlmodvptnl Posts: 1,352
    It doesn't appear that all of them do. The detonation does seem to be more chronic as my buddies '00 has the ping under load but no mechanical noise. I still stand by my gut feeling that a motor that has loose clearances now will not last as long as one that's tighter initially. I will concede that there doesn't seem to be a definitive answer yet as to what's knocking but all indications point to pistons, like the early Ford motors.

    My last motor I built I ran TRW forged pistons that actually called for a pretty tight .003 clearance for forged units. I've seen some forged pistons run .005. Cast are usually in the .002 range. Let's say, hypothetically, that oil usage and cylinder seal is compromised at .009 piston/cylinder clearance. If the GM motors are already at .006-.007 causing a little cold knock, wouldn't that leave less time till it reached that .009 number???
  • quadrunner500quadrunner500 Posts: 2,728
    All other things being equal, I guess so. But we don't know what the clearances are. What some have been told, is that the piston skirt is too short, which if true, would not be the same thing as loose clearance.

    By my reckoning, there is only scattered commentary on this topic, less than 30 posts total at this point. Problem is real enough if you have it though.

    Diesels have loose tolerances, and seem to run a pretty long time by the way. One thing I'm keen to, is how long it takes the crankshaft to stop turning when you shut it off, new...versus how long after a few thousand miles. I think other things are at play also, like how you maintain it, frequency of the oil changes, did you stick to the break-in schedule, lots of high rpm early loosens them up etc.
  • modvptnlmodvptnl Posts: 1,352
    we'll just hurry up and wait. I'm still curious, however, if GM offered Ryan a fix or replacement if he'd decline and say, "It's a truck, I expect a few knocking noises." !!!

    Do you have the specs on diesels??? I always thought because of the enormous compression they'd be very tight.
  • ryanbabryanbab Posts: 7,240
    i would decline an engine fix. I dont want them ripping it apart and then you dont know what will go wrong.

    I would however take a new engine (if it came down to that) or an extended warranty.
  • modvptnlmodvptnl Posts: 1,352
This discussion has been closed.