Knock Knock….It’s Your GM Engine Knocking

June 07, 2012
By: LemonLaw

It’s a problem we have seen for over a decade– a piston slap and engine knock on cold start with various General Motors vehicles. Now, the latest technical service bulletin is out and it includes 2012 models as well.  Here’s a copy of the TSB courtesy of our friends at (website no longer available, links removed).

The most current models affected are 2007-2012 Cadillac Escalade, 2007-2012 Chevrolet Silverado, 2207-2012 GMC Sierra, 2007-2012, GMC Yukon Denali, and the 2007-2012 GMC Yukon XL Denali equipped with the 6.2 liter engine.

According to the TSB, the noise may begin in the first 12,000 to 15,000 miles and lasts between 5-30 seconds.  The noise is more noticeable when the weather is below 50 degrees.  The engine knock may be caused by an interaction between carbon that has formed on the piston, the piston motion, and the cylinder wall.  GM engineering feels that this engine knock or piston slap is not detrimental to the vehicle.  We are not so sure of that.

If you have been repeatedly for your General Motors engine knocking, it is essential that you look into your rights under State Lemon Laws and Federal Warranty Laws.   You could be looking at recourse and the help is free.  Contact a Lemon law Lawyer in your state for more information.

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57 Responses to “Knock Knock….It’s Your GM Engine Knocking”

  1. #1 LemonLaw says:

    @Brian: If you go to, we will be glad to review your claim free of charge to see if there is something we can do.

    • #2 Derrick Tillison says:

      I have a 2007 Escalade that’s paid for, the engine knocks real bad. What’s me recourse. Please help.

      • #3 Mike Bresnock says:

        72,000 miles engine noise until engine is warm….sounds like ticking then goes away. Particularly noisy in cold temps.

        I would like to have this fixed!

        • #4 Devon says:

          I have a 2007 GMC Denali with a bad engine knock what can i do.

          • #5 Brian Camp says:

            I have a 2007 Denali that knocks heavy at start up in any temperature. After the knock dissipates a ticking is noticable during slow and medium acceleration. The tick be ones more rapid as speed increases.

            • #6 Mark says:

              2011 GMC Sierra 6.2 engine, bought used with 50k miles, paid cash, engine knocks especially at cold temps, truck surges at stop signs and intersections.

              • #7 Mark says:

                I have a 2007 Denali with 102k miles and it doesn’t matter what the temperature is outside my truck knocks for the 1st 15 to 20 min before going away……

                • #8 William andrews says:

                  My 07 escalade ( 6.2 L ) has a sever piston slap . Started about 58,000 mi. .After three trips to the Caddy dealer in Pgh. and many calls to G M C I have learned they are very aware of this but no call back . I now have 90,000 mi. The slap has turned in to a violent knok @ all temp. .I have owned GMC all my life , always got 265,000 to 325,000 mi. before selling or trading in . I am a professional engine builder . Now @ 70yr. old. I no longer can do my own repairs .I finially got my wife & I abeautiful

                  • #9 Vic says:

                    I own a 2007 Cadillac Escalade EXT. I am having the same cold start piston slap that does not go away in tell the engine reaches normal operating temperature. Even at normal operating temperature I can hear a slight knock. Now the fact that GM discontinued the L92 gm goodwrench crate engine and replaced it with a new L92 crate engine part number 19329865.
                    GM says its a new improved version of the L92 has better hyper alloys that don’t expand as much allowing tighter piston to wall clearances.
                    no more knocking is a good thing…GM should make the knocking issue a recall, it’s embarrassing driving around in a fancy Cadillac Escalade EXT….. the flagship of pickup trucks with a knocking noice, a knocking noice that brings thoughts to mind like………wow that noice sounds so wrong on a $75,000 Cadillac, is my engine going to blow up.

                    • #10 mara says:

                      Just reached 71,000 miles on my 07 Cadillac Escalade EXT. I have lost sleep for the past two weeks with this engine knock tick or whatever you want to call it. I have been in and out of the shop and still going without any resolution. I’m hoping to receive some help from people that have same problem. Please help…Freaking out!

                      • #11 John says:

                        I have a 2010 Cadillac Escalade with 64,000+ miles on it. The engine knock started about a week ago and it do not matter what the temperature is outside. Even when the SUV warms to the proper temperature, the knocking is there. The oil pressure is fine so that is not the issue.
                        It is not good riding around in a $75,000 automobile and the knocking announce your coming.
                        What will be the next step to resolve this issue? Any help will be greatly appreciated

                        • #12 LemonLaw says:

                          @John: I would reach out to GM to see if there are any silent warranties for your year, make, and model.

                          • #13 Carolyn says:

                            I have a 2011 GMC Denali paid Cash is nocking bad took it too GMC will not do anything with me to pay my engine but I paid cash for this the same in GMC should take responsibility I’ve read the reports and I’m disgusted i have a 1995 GMC truck have over three hundred and thirty thousand miles on it with no problem

                            • #14 LemonLaw says:

                              @Carolyn: Now I see what you are speaking of. Please contact NHTSA at to see if there are any recalls or technical service bulletins.

                              • #15 Owais says:

                                Hi, I have a 2008 Gmc yukon denali with 6.2 v8 engine 108500 miles, it knocks at cold starts up for 5 seconds and the noise goes away as the engine temperature comes to normal. What is the next step to solve this problem?

                                • #16 Paul kelly says:

                                  I have a 2013 Silverado with 31,000 mi.
                                  Sounds like a thrashing machine for about 5
                                  Minutes. After start. The dealer agrees something
                                  Is wrong but Gm won’t do anything.

                                  • #17 Brandon MacKinnin says:

                                    ’07 Yukon Denali. Came from California. Engine knocks when cold for 5-10 minutes. Has 155,000 miles on it.

                                    • State: Alberta Canada
                                  • #18 Benjamin J Liell says:

                                    2008 Yukon Denali with 6.2 and piston slap. Not the original owner, just bought it.
                                    Any recourse?

                                    • State: MI
                                  • #19 Rob Mcgonigle says:

                                    I have a 2010 silverado that sounds like a diesel it has 35000 miles I just paid 20000 for and I think I’m going to let them take it back I’ll just continue driving my 04 silverado

                                    • State: Pennsylvania
                                  • #20 Shawn says:

                                    2012 GMC Sierra 1500, 11,000 miles started hearing ticking/knocking on start up, it lasted about 15-30 sec. the local dealer said it was normal, for louder and longer around 25-30k miles, brought to the same dealer, they said the same thing, I’m hit 60,000 mile, brought it back to the dealer, they told me it was carbon buildup, they did a carbon clean and told me to drive it for a 1,000 miles. I drove it as they said, still making the noise, I brought it back to the dealer now that it’s out of warranty they told me the engine needs to be replaced for $7,000 plus dollars. Real nice GMC

                                    • State: Ct
                                  • #21 T.B says:

                                    I have a 2012 Serria Denali 6.2l the engine is knocking took it into a shop they said it was the timing chain when I took it to another shop to double check they told me it’s a commen issue with these engines. GM knows about the engines being shitty and won’t do anything about. No recalls on them either.

                                    • State: Saskatchewan, Canada
                                  • #22 Frightened says:

                                    2012 Denali here, same problem <60k miles. I'm very concerned.

                                    • State: NY
                                  • #23 James says:

                                    2013 Sierra Denali 1500 6.2L 57000 knocks at any temp until the engine warms up. It is worse when the temp is below 50 degrees. The dash is also cracked. This GMC has been nothing but a disappointment!

                                    • State: SC
                                  • #24 Jerome Sterling Hicks says:

                                    2008 yukon xl slt 5.3L with a tapping lifter, right after 2k in transmission , 800 on bad electrical wires, 1200 on both axles , cv seal rotors and brakes, and now the tapping, and of course its paid for…thx GMC for your long lasting junk! Ford, Toyota, Honda will get my money from here on, i have been a GMC owner since 1987, really disappointed in America’s foremost auto manufacturer.

                                    • State: Maryland
                                  • #25 Juan ibarra says:

                                    I have a 2007 Escalade , it has a nosie knock at cold start , it will knock for about 2min then it will go away , I just ran out of factory warranty what can I do

                                    • State: Texas
                                  • #26 Tom Royal says:

                                    2007, Piston Slap like everyone else, very embarrassing. I don’t even like to move the truck in the mornings.

                                    • State: MD
                                  • #27 blake says:

                                    Same here, any help makes it hard to sell……

                                    • State: mi
                                  • #28 Chris Kelliher says:

                                    I own a 2008 Denali 6.2, we purchased the vehicle with 35,000 miles we now have 138,000 miles. The engine has always ticked until it warmed up every day, every start cold in morning in a heated garage in winter or cold start in summer. Mention to dealership and was told its normal and that if it goes away when warm not to worry about it so we live with it to this day. Have been looking at rebuilding the engine and keeping vehicle because its in great condition. every time I start it I’m reminded of the noise.

                                    • State: South Dakota
                                  • #29 Mike Krzesowiak says:

                                    2011 yukon denali xl 6.2,,engine knocks bad for about 10 mins until warm,,truck has 83,000 miles,please help get this fixed!

                                    • State: MICHIGAN
                                  • #30 Nathaniel Jones says:

                                    O7 cadillac engine ticking piston slap ing dam Cadillac help

                                    • State: GA
                                  • #31 Shannon Jacque says:

                                    2012 Yukon Denali. I purchased this vehicle used four months ago. The engine started knocking, so I limped it over to the dealer that is saying it needs extensive engine repair or an entirely new engine. It has less the 100,000 miles, but is just outside the 5 year powertrain warranty. GM is not wanting to help with repairs. Anyone else have this issue?

                                    • State: TEXAS
                                  • #32 Brittney says:

                                    We have the exact issue. 2010 yukon denali xl. 89000 miles. Bought it used one previous owner. Regular oil changes. Drove it to work one day and the rattling started. No previous issues except for the auto start on occasion. Brought it back to the dealer who told us the exact same. Told us 3 grand for the engine fix and I’ve read multiple others with the same issue. Why is there not a recall on This? We had the thing 6 months now we owe over 26 grand on a vehicle sitting in the driveway ruining our credit because we had to get a reliable vehicle. Gm needs to know they are ruining lives and people have families to take care of. We shouldn’t be worrying about how we are going to pay for something that is clearly a gm issue with multiple other vehicles/consumers.

                                    • State: Il
                                  • #33 Dboy says:

                                    I️ have a 2013 Cadillac Escalade platinum edition bought it a month today drive fine till this morning it made a knocking noise upper on motor all fluids are fine oil pressure everything paid 35k at a Chevrolet dealer sold as is no warranty and I️ called them back they said pay a inspection fee and that all they could do it makes me mad because they ddnt offer to tow it or nothing and if it’s something I’m out of pocket can’t trust no dealer no more wish someone can help what do I️ do if it’s the motor do I️ just take there junk back and don’t pay nothing it’s stressing

                                    • State: Tennessee
                                  • #34 Valdez says:

                                    2018 Silverado.2768miles.5.3…only have had a month … missing n light knock, taking it to dealer tomorrow….

                                    • State: Tx
                                  • #35 Silas Magee says:

                                    We live in northern Vermont bought the truck new 2012 Chevy Silverado crew cab All Star Edition Z71. At the end of the day all I’ve done with her on these harsh Vermont dirt roads oil changes and a brake job and tires period while getting new tires though I was pleasantly surprised that after three and a half years of beating the truck on dirt roads in Northern Vermont my alignment was still within specs. The funny thing is I made a video this past winter the truck being 5 years old at how quiet it was idling in the front yard and this was sub-freezing temperatures in December probably single digits. Not shortly after that I’ve noticed the engine tick or slap or knock whatever you want to call it. And I’m guessing it is what it is because after you let the truck warm up and you drive it for 20 minutes and then you let it idle she is as quiet as can be. Just drove her to Maine she averaged 20 and 1/2 miles per gallon kind of hard to say mechanically she’s not running right. So all in all knock on wood she’s been good to us but it is damn annoying

                                    • State: VERMONT
                                  • #36 Tiffany says:

                                    I bought my 2010 Yukon Denali with the 6.2 engine in 2014. I’ve always heard the slapping sound and had issues here and there. Well, January 2018 had to have all 8 lifter rods replaced, and all kinds of other things. It’s now May 2018 and the lifters have collapsed again. The mechanic is GM certified and knows what he’s doing, I just think I bought a lemon with issues from the beginning. GM needs to take responsibility for this lifter issue. As well as some other common issues.

                                    • State: NC
                                  • #37 Joel says:

                                    I have a 2010 GMC yukon xl denali with 126000 miles. It has loud knocking noise all the time.It gets worse when you hit the gas pedal.

                                    • State: Delaware
                                  • #38 colin says:

                                    I have a 2012 Escalade with 84k miles, eight months out of warranty. Synthetic oil every 5k miles, always premium fuel. Knocking started suddenly brought it into the dealership and found out I was just out of warranty period (time flies). Brought it to my trusted local garage and got an estimate for $2800 to replace all sixteen lifters (or $1800 to do the eight on one side).

                                    • State: TX
                                  • #39 Jarade Purk says:

                                    2007 Yukon Denali 167,000 miles piston slap followed by a rod shooting out the bottom of my motor. Have had this seriously 2 months, ran fine all day then just as I was leaving work to go home started knocking then lost power and a stall which was the final.

                                    • State: IA
                                  • #40 THOMAS says:

                                    2010 Yukon xl Denali 115k
                                    Just dropped #4 lifter. What recourse do I have? Thanks in advance

                                    • State: NY
                                  • #41 Justin says:

                                    2010 GMC Sierra Denali. Knocks loudly at cold start, and gradually gets quieter. An audible ticking still lingers for as long as I drive it thereafter. The ticking increases as I accelerate. Quite annoying to say the very least.

                                    • State: KY
                                  • #42 Leon says:

                                    2012 Denali 6.2 truck nocking in bottom end some where around the transmission 5- 15 min it does that / my 2011 Denali 6.2 did the same so somebody need to fix the problem or recall all 6.2

                                    • State: Miss
                                  • #43 James Brooks says:

                                    I have a 2007 GMC Yukon Denali with 139.000 miles, started to knock two weeks ago, it had a ticking engine noise prior to that. I took it to the Chevy dealership on 10/17/2018 and the service manager told me it’s I GM cam problem with all those vehicles and they (GM) know it , but want recall them, problem bankrupt them.
                                    He said it would cost around six thousand dollars to fix it, and wouldn’t be worth it, would be better to get a new engine, but that wouldn’t be financially good because of the year and miles.
                                    He said a lady has been bringing her 2014 GMC Yukon Denali in for oil change for over two years and it’s been knocking, and she said she will drive it til it stop, and will Never buy another GM product, I agree and will never buy another GM crap myself.
                                    Do we have a recourse, can a class action lawsuit be accomplished.
                                    Please help..
                                    J Brooks

                                    • State: Tx.
                                  • #44 Leon says:

                                    2012 Denali with 80,000 miles reported the problem too dealership about the knocking service manager said he didn’t hear nothing/ it does it at first starts it makes low knock though out the day I use premium gas so I don’t know what to do with it now

                                    • State: Ms
                                  • #45 Linda Terrill says:

                                    2007 Denali. Same story as everyone else. This vehicle has been kept up quite well. Heard small ticking noise every once in a while. But always went away very quickly with no other issues. Then the Traction Control light came on a couple times with no apparent reason. After that truck died a couple times but started right back up. Took trip to Claremore Ok. Half way there the truck acquired a clicking, tapping noice. Stopped at a rest area. Let truck cool off for about 15min. Started right up no noise. Drove about 5 miles. Noise started again only a little louder. Pulled over let truck cool off again. Started right up no noise. Repeated this several times to get on into Ok. Next day no noise drive all over Ok. for 2 days with no problems. Upon the return home things went bad. On the interstate, running about 80 mph. Traction control light came on, the engine symbol came on and truck shut off. This all happened in a split second. Some how got the truck off the road. Waited about 10 minutes. Then restarted truck. Loud noise again, only it has not quit sense. So not only do I have a truck that has loud noise and don’t know why. We were really lucky to have not been in a horrific pile up on the interstate that could have killed a lot of people. These vehicles need to be recalled before that very thing happens and customers need to be compensated in order to buy a different, safe vehicle. Linda Terrill

                                    • State: Missouri
                                  • #46 John says:

                                    I have a 2011 yukon Denali with 6.2L and mine started the loud knock the other day. Has me scared to drive it and I refuse to pay 7000 bucks for a new engine. GM needs to recall these engines ASAP

                                    • State: Va
                                  • #47 Michael Wilhite says:

                                    I have a 2007 Escalade Same Issue but I am near 180k I myself as soon as possible I am going to do the Carbon removal trick.
                                    I will remove the air intake filter and tubing running to the throttle body. With someone in drivers seat to work throttle with engine started have your water spray bottle ready and begin to spray into mouth of throttle body while throttle is being revved up! You will notice smoke and black soot from exhaust. years ago we used to do the same thing with transmission fluid into the Carbs. its a 400+HP motor drive it Like you stole it! P.S. Engine has to be running when you do it LOL If you Dog it Carbon will come! Blow it out on a nice stretch of Highway!

                                    • State: IN
                                  • #48 Cody says:

                                    2011 Sierra Denali has 113k on it. Been ticking when cold since about 80k. Lately I’ve noticed it would tick till it got to operating temp and then would quiet down. Now I have a slight tick when accelerating. Dealership said lifters would need replaced and it’s 18 hours of shop time plus Parts.

                                    • State: MT
                                  • #49 Kurt Johnston says:

                                    2007 Yukon XL Denali w/ 210,000 miles.
                                    Obviously the same story as everyone else:
                                    – Started with small ticking noise, but always went away after warning up.
                                    – Traction Control light comes on periodically for no reason.
                                    – Lately it has had a very loud clicking noise from the driver’s side of the engine.
                                    – All signs point to bad lifters w/ estimate of major time and money to replace.

                                    Answer I don’t see here is what to do about it or how do we get GM to own up to it?

                                    • State: KS
                                  • #50 Eric Seckman says:

                                    Same problems with ours a 2013 GMC Youkon Denali XL we bought it about 2 years ago with about 80,000 miles and paid for a extended warranty. Now just this last weekend we were driving and all the sudden the engine starts making a “LOUD” banging sound that changes when the rpm’s of the engine changes. We made it home driving about 30 mph in a 50 mph area with our hazards on. The next morning you we called the GMC dealer where we bought it and they asked the mileage we said 120,000 they said the extended warranty we purchased ran out at 110,000. Well we can’t afford the dealers labor rates so we took it to our local NAPA car care center they diagnosed it as a lower internal engine knock and said if we keep driving it that the piston connecting rod would come thru the engine block making the engine no good as a core so more money would need to be spent. They wrote a estimate to replace the engine with a rebuilt motor for $8,300.00 and could be additional things found during repairs. We don’t have that kind of money as we are still paying on the loan for the original vehicle purchase. We tried to get a loan but with the vehicles loan payment our debt ratio is to high for then to lend us more money. Come on GM recall these engines “please”
                                    State = Arizona

                                    • State: State
                                  • #51 Jamie says:

                                    Braught a used GMC Dinali 2013 paid cash cost me over $19,000 had it for year but it was 90,000 miles on it and it started showing traction control issues that it started having lift or issues wouldn’t run one time started act like it was going to die there was a loud noise took it in it was my AC box wasn’t closing so it was trying to shut my engine down I didn’t know that it was had anything to do with the AC got that fixed now my piston is making a huge noise the car won’t run it’s in the shop now they’re saying it’s possibly one piston that needs to be replaced everybody look at your AC boxes to see if they’re opening and closing

                                    • State: Oregon
                                  • #52 Dave Anderson says:

                                    2013 Silverado LTZ 6.2L developed slight tick on startup on cold days about 5yrs ago @ 20k miles. Brought it to dealer They said it’s normal, GM won’t fix it, it’ll be fine.
                                    Little over a year later @ about 35k mi tick on startup got louder, And now did it regardless of outside temp. Another dealer(different state) told me it’s a known issue with these motors but GM is refusing to do anything. Again dealer said It’ll be fine, he’s seen these motors last over 300k mi with the tick.
                                    Couple yrs later @ about 50k tick now became a knock on startup on cold mornings. Now that it’s out of warranty I’m told I probably need a new motor.
                                    At 77k mi now and the knock is horrible. Sounds like it’s going to throw a rod through the side of the block. I am extremely meticulous about caring for my vehicles and I’ve done all oil change and maintenance on schedule regardless if it was needed or not. Only drive it about 10k mi a year. Truck is still immaculate after 7 years except for the time bomb under the hood. It’s pitiful my 97 tahoe 5.7 with 250k mi runs better than my 2013. And all GM says is sorry about your luck you need a new motor and you got to pay for it. But hey we will fix your airbag for free….. But…. we don’t have the parts so your shit out of luck there too. Deal with it. My entire family & I have been diehard chevy fans & customers as far back as anyone can remember. Sad that is over. We are no longer willing to drop 65k to 100k on a vehicle who’s manufacturer refuses to stand behind their product with a known manufacturing flaw. I don’t understand how they can ignore this & keep this quiet for 14 years when EVERYBODY with this motor has the same problem. How is this not the definition of a lemon? I love my truck I just want it fixed. Has there been any progress made with this class action? Goodbye chevy.

                                    • State: NJ
                                  • #53 LemonLaw says:

                                    @Dave: We would like to see your repair records. Please reach out to Michael Sacks at 800 536 6652 ext. 131 or via email at

                                    • #54 Ryan says:

                                      Just bought a brand new 2021 Yukon Denali. Took to my local GMC dealer for an oil change at around 3800 miles – didn’t need it until 5,000 miles but I was going to leave for a 3,000 mile road trip a few days later and wanted fresh oil. Fast forward 10 days, I’ve got 7,000 miles on it and literally the moment I pulled onto my street, that obnoxious ticking noise started. Called the GMC dealer, they told me to bring it in. The next day, as I’m driving it to the dealer, the knocking started. All said and done, they had to take apart the entire engine to replace the lifters and rods. Warranty 100% covered of course (would be a near $5,000 repair out of pocket), but the GM service writer told me that it could happen again, and if it happened while I was on my journey, the engine could’ve been totally wrecked. I bought this vehicle for cross-country road trips with my kids and now my confidence in it is near zero. Does Lemon Law allow me to return the vehicle if the knock happens again?

                                      • State: IL
                                    • #55 Scott Hooks says:

                                      I have a 2011 GMC Sierra with 135,000 on it. I bought this new. I had it to the dealer a few times and said about the noise. They said it’s normal. It got alot worse after it hit 100,000. They can’t fix the engine but they want to fix my airbags. How’s is this fair?

                                      • State: Pennsylvania
                                    • #56 Tommy Cross says:

                                      knocks when starting up truck starts to knock when starting up

                                      • State: Illinois
                                    • #57 Tommy Cross says:

                                      Truck makes loud knocking sound

                                      • State: Illinois

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