6.0 liter knock

silverado6 · July 2001

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.

jwhaelen1 · July 2001

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: http://www.cartalk.com You've probably heard them on the radio before. Good luck!

wight1 · July 2001

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.

sf0383 · July 2001

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

akjbmw · July 2001

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. ;-)

gumpymac · July 2001

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.

nerd · July 2001

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.

rackmaster287 · July 2001

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.

whatsachevy · July 2001

'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.

bobsquatch · July 2001

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.

justom · July 2001

Nerd,

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?

sonjaab · July 2001

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

minikin · July 2001

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

rayt2 · July 2001

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.

nerd · July 2001

Justom,
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.

ryanbab · July 2001

"It has 80K miles without any problems"

So why not leave yours alone?

"if it aint broke dont fix it"

modvptnl · July 2001

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!!!

ryanbab · July 2001

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.

Ryan

rackmaster287 · July 2001

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.

modvptnl · July 2001

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.

ryanbab · July 2001

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.

modvptnl · July 2001

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!!!!

quadrunner500 · July 2001

I think they will.

modvptnl · July 2001

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!!!

minikin · July 2001

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

quadrunner500 · July 2001

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. Anyway...no problem with DURAMAX diesel!!!

I always agree with you when you are right!!!

modvptnl · July 2001

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???

quadrunner500 · July 2001

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.

modvptnl · July 2001

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.

ryanbab · July 2001

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.

modvptnl · July 2001

slamit78163 · July 2001

After reading a cornucopia of indifference to which truck manufacturer(Ford vs GM) has the best reliability record, I've come to the following conclusion: Up until June when I purchased a 2001 GM 1500HD Serria Crew, I was a born and bled Ford Blue owner for 26 years. My last vehicle was a Club Wagon E-150 I/a 5.8 that had 235,000 miles when I sold it. This car was in excellent mechanical shape due to responsible maintence. I chose the 1500HD due to desire for a light duty truck, (crew) with a superior drive line and 6 foot bed, plus the killer deal that would have been impossible purchasing the Ford. Do I feel the Ford Super Crew is an inferior truck? Absolutley not. For me, the 1500 is the vehicle for me at this point. Did Ford have a history of poor reliability with their engines? Certainly not any less than Chevy or GM. My Dad bought a beautiful Ford 4x4 in 1985, had a knock in the engine, took it back to the dealer and they fixed it. He then towed a 28 foot trailer around the the US for 8 years. Is there reason for concern w/ the new 6.0, from what I have read and HAVE PERSONALLY EXPIERIENCED, I believe so. While my 6.0 has 6500 miles, I experience a little valve train noise first thing in the morning, otherwise it's as smooth as glass. However, this past weekend, I stood next to a 2000 1500 Silverado at idle, it had a noise so loud it sound like a hammer pinging on an anvil. Will GM stand behind their products? For me, I certainly hope so. But when I read observations about which truck manufacturer used forged pistons vs cast or what motor will last longer or what manufactuer will stand behind it all, I'm unimpressed. After being around cars all my life, I'll treat this new GM 1500HD w/ the same responsible maintence I did w/my Fords for 26 years. If need be, I have confidence that GM will stand behind their ride if need be. But for me, the GM has big shoes to fill, size 235,000 to be exact .

modvptnl · July 2001

I'm glad you're unimpressed!!!! If you can't understand that Ford replaced knocking motors that had the wrong clearances with BRAND NEW motors and that GM is still dicking around trying to find the problem.......well, I'm not sure what else there would be to be impressed about. Even one of the most knowledgeable GM owners on this site sort of made fun of the way GM is trying to band aid the pinging problems with soaking your cylinders over night, which he thought might even be contaminating the oil causing a knock.

BTW, glad you enjoy your truck and I hope that you don't have any of the probs that the GM's seem to be having........so far.

iceracer · July 2001

Truck is a 00 2500 with 6.0 built mid July 00. I have the same tick/knock as most all of you have described right from new. I took the truck back to the dealer (3rd time) for the same problem and got the usual BS. I did not do the suggested decarb because I nearly up chucked when the service foreman told me it was "carbon deposits on the ring lands". I then hooked up with a private service dude that used to be a GM tech. He checked everything he could and did not come up with a positive ya it's pistons or liters etc. He did say however that he feels there is a serious enough problem that ignoring it will cause a longevity problem. I followed the exact break in schedule and have been very careful on the maintenance (I do my own). Truck now has 30K Kilometers. The sound seems to be worse closer to the end of the oil life. Is anyone else experiencing the same thing? It ticks/knocks at cold start for about 15 minutes. It doesn't sound too bad at the initial idle when the rev's are a little higher but as soon as the computer lets the idle down, it idles really quite slow and the tick is VERY! noticeable. It annoys the $&&^$(^I^$$# out of me!!!!! The tick is there until you get the engine right up to temp or you pick the revs up (sitting still) manually. It goes away (engine still cold) when you rev it up to about 1200 to 1500 rpm. If you stop after being out and start it up with temp at about 1/2 of normal it ticks then as well. I am keen on having it fixed but dread the thought of taking it to a dealer to tear down. On a positive note, I love the truck over all with respect to ride, handling, power, towing ability and looks. Other than the tick at idle the engine is soooooo sweet. I will look forward to reading this message board in the future for possible solutions. I note that most of these posts are from the US of A. Is there any fellow Canadians out there with this same problem?
Regards
Tim B

quadrunner500 · July 2001

On the diesel compression thing...high compression ratio yes, but a fair amount of blow-by too. It was a diesel mechanic at Mountain States Ford in Commerce City Colorado who told us diesel tolerances are very loose, thus all the knocking and clatter. No first hand knowledge though...

Of course, that's Powersmoke diesel...Duramax bound to be muchhhhhhhh tighter

quadrunner500 · July 2001

Believe I heard Benny Parson talk about Nascar qualifying motors are built loose to turn high rpms. Course...that goes against the longevity feature.

As for what's happening with these 6.0L engines, can't say. My '99 was 5.3L fine. Definitely felt tight, like it could go 200,000+ easily. What could have happened since then?

My '91 LX 5.0 Pony car had a bullet proof engine that was much more user friendly to the go-fast guys than the OHC that replaced it. Still, that engine was wheezing at 4800, and past done at 5200 rpm. These Chevy truck motors are turning 5600. Food for thought.

modvptnl · July 2001

There's no way a qualifying motor could go 500 miles. And that's my whole point as far as loose tolerances.

That's interesting on the diesel info. I find it hard to believe you could make 17+.1 compression with loose tolerances.

I too am a 5.0 fanatic!!! That and the SBC have no comparison as far as aftermarket support.

What's sad to me is the fact that Mustangs clobber camarobirds in the showrooms. The 4.6 SOHC is up to 260 HP but is still no match for the mighty LS1. The Cobra R 5.4 is N/A and runs 385 horses. No need to upgrade the 'stang with that motor 'cause there is no competition(as far the bean counters go)

Am shopping for a Lightning tomorrow to replace the Cobra. Will offer $500 over invoice and want wholesale book for the Cobra.(17,000) If no deal I'll wait for the new paint(Ford authorized it and I'm scheduled for the 13th) and go Lexus/Accura shopping. The ball's in their court!!!!

quadrunner500 · July 2001

>That's interesting on the diesel info. I find it hard to believe you could make 17+.1 compression with loose tolerances.<

Remember, it's not the static compression ratio. Compressing air 17:1 or 8:1 doesn't compare to the combustion pressure that develops when you burn a fuel mixture. In the case of the diesel, compression ratio is not so important except you need it to produce the temperature for ignition when the fuel is injected. Consider, it's 17:1 AND turbo'd.

quadrunner500 · July 2001

>And that's my whole point as far as loose tolerances.<

Loose tolerances are still a leap of faith on LS1's. I think the short piston skirt has been mentioned.

One other correction...when I read about the piston slap in 5.4L Tritons in Truck Trend, the fix offered was not a new engine, just new pistons...fix was not offered...you had to be affected, and you had to ask.

modvptnl · July 2001

Both dealers I deal with said it was a new motor(long block, yes) which if you think about it would be cheaper than a COMPLETE tear down and machining to fit new pistons??? OBVIOUSLY it was only for trucks affected!!!

quadrunner500 · July 2001

Mod, I didn't read it online. It was in the printed magazine as a sidebar in one of the F150 issues. Could probably find it in the back issues at the library...but I definitely remember they were offering pistons and wrist pins, not long blocks, according to TT.

modvptnl · July 2001

we can't believe everything in those magazines, otherwise nobody would buy chevs and we'd all be driving toyotas. LOL!!!!

bigsnag · August 2001

Actually they were only offering short blocks. I know this because several people with '97 and '98 trucks wanted long blocks so they could get the "Power Improved" heads and the 260 horses that come along with them but Ford would only give them a short block. They had to reuse their old heads and hence they stayed at only 235 hp. BTW, it was a problem which affected a statistically small number of engines (probably the same situation with the Chevy engines). Mine has yet to develop ANY odd noise at cold start-up. I've been listening for it on a regular basis.

modvptnl · August 2001

Once the old motors were depleted. Sorry about being redundant but I highly doubt pistons would be replaced at the dealer level. Unless it is going to be a butcher job.

tommyclark · August 2001

I recently purchased a Chevy 2500hd crew 4X4 and previously had Fords for about 7 years with NO problems. Let's end the argument! Look at this same Web site under Ford F150 Problems, READ THEM then go back to Chevy Silverado problems. Then look at the introduction page and see the qty of letters. As far as this web site goes Chevy beats Ford hand down for customer complaints. Chevy 1287 complaints to Ford 123. Also the Ford people are complaining about not having luxury items as well as mechanical problems.
By the way i like my truck us it off road on the beach every weekend, probably will rust out before the 6.0 goes! If i could only solve the high speed vibrating/whistle sound.

markbuck · August 2001

using 87 octane on my 2500HD 6.0L. Similiar to my 99 4.8 ping.

Went back to premium, works fine.

Really happy with the truck at 7,000 miles.

whatsachevy · September 2001

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!!!

6.0 liter knock

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