2007 Yukon Denali 6.2l Engine Knock After Start-up

[DRC]

DRC,

This is considered normal. The noise is usually noticed on initial start-up when the temperature is below 50 degree Fahrenheit. It may be more pronounced on the first cold start after a long trip. The noise typically disappears within the first 5 - 30 seconds, but may last longer in extreme cold temperatures.

The noise is not detrimental to the performance, reliability or durability of the engine. The noise does not have any affect on the longevity of any of the engine components.

Louis
GM Customer Service

My garage is 70 degrees and this knock just started, I'm 59 yrs old built plenty of race engines in my younger years. Never did I ever have a engine that started knocking like this that the engine did not fail soon after.
I know GM claims this is normal, I still say hogwash.
We had a 2006 Yukon Denali 6.0 that we traded in with 35k miles on it with no so called normal piston knock.
I guess I eventually will have to trade in and buy a non GM product.

 

[AaronIROCZ]

My 2007 Yukon makes a noise from the transmission when I start it up but when worm it sounds good. I have no warranty so if you find out what it is send me a answer thanks .

What type of noise is yours doing?? Where are your catalytic converters located?? My 02 Silverado did this as well and it ended up being the converters were loose and knocking around in the housing. At first it sounded like an engine knock but after a while it turned out to be a random knock and then lost performance.

 

[quattrotman]

DRC,

This is considered normal. The noise is usually noticed on initial start-up when the temperature is below 50 degree Fahrenheit. It may be more pronounced on the first cold start after a long trip. The noise typically disappears within the first 5 - 30 seconds, but may last longer in extreme cold temperatures.

The noise is not detrimental to the performance, reliability or durability of the engine. The noise does not have any affect on the longevity of any of the engine components.

Louis
GM Customer Service

This is not normal. GM takes this stance because it is a problem which affects hundreds of thousands of vehicles and they would likely go broke (again) if they recalled it. Yes, other manufacturers have this problem but it is not nearly as widespread and pronounced as with GM and the other manufacturers own up to it and fix it. Both Ford and chrysler have recalled vehicles for piston slap but GM considers it normal...hmmmm??? GM's position is that they call it normal and that is what everyone is led to believe because they say its normal. You are fighting a losing battle if you try to get it fixed by GM. Very few win that arguement including myself with my escalade. It, in all likelyhood will not cause any catostrophic failure and your motor will probably last but some of them get really bad and the noise will not go away. For me, it's embarrasing and unacceptable for a vehicle that costs as much as an escalade does. Good luck with your issue, I hope you have better luck with the dealer than I did but they are pretty firm on their position that it's 'normal'. IMO, I think it's dishonest GM.

 

[pmexpert]

Guys, it's all ******** that it is normal. I already changed 2 pistons(twice in the same cylinder), coz somehow one part of piston split after that noise appeared. The part has been broken inside the cylinder by the pistons and thrown out through headers. Small metal parts were found close to cats. I hear that sound again, and noticed dealer about that, so will vizit them tomorrow. I explained that need to change all the lfters in that lifters and cam(if I will see any wear on it).

 

[Preludepearl417]

Normal. My 07 Esky with 68k on it does the same thing when i start it in the cold. Agree, it sounds like a diesel for a couple min. I think its normal.

 

[DRC]

Ok ladies and gentleman I got good news and bad news on this so called normal engine knock after start-up.

Bad news first, for the GM customer service and the ones saying this is normal, I'm sorry actually very happy to report HOGWASH.

There is a TSB # 100601008C that address's this very problem.
This is some engine tearing down to correct this problem.

The good news for us that feel this is BS we have a TSB now that address's this problem.

The bad news for us the non believers on this BS is getting the dealers and GM to repair the problem.

I got this info and TSB # from apparently a honest few and far in between GM dealer.

They wanted me to try one thing before I came back with my Denali for them to observe the knock when cold.
That was to at least change the oil filter from my NAPA Gold to the AC delco, to satisfy GM.
Just to make sure its not the oil filter causing the problem, so I let them do a oil and oil filter change today.
And check it out this coming week, then take it in next Friday 3/16/12.

 

[dlr2416]

I have a 2008 Denali with the 6.2l and it does the same thing. I took it to the dealer and they said they couldn't hear what I was talking about. I'm just waiting for the engine to die then they will have to replace the entire engine. Way to go GM products and service folks.

 

[DRC]

I have a 2008 Denali with the 6.2l and it does the same thing. I took it to the dealer and they said they couldn't hear what I was talking about. I'm just waiting for the engine to die then they will have to replace the entire engine. Way to go GM products and service folks.

What I did was I left my Denali over the weekend so the engine was nice and cold. I then arrived @ the dealership Monday morning and held their hands as we walked out to my vehicle so we all could hear the normal piston knock together. The GM people are not to be trusted when alone.

 

[dlr2416]

I know exactly what you mean, because I still have an AC issue that they have had my Yukon for over a month for and it is still not fixed.

 

[Big Bad Allis]

I haven't heard the "Piston Slap" on my 11 Yukon 6.2. However I don't think that most engines will fail because if it. In our company car program there are a lot of GM vehicles that have the "Slap". We run the cars up to 225,000 or so miles before changing vehicles. The only vehicles that have had engines replaced at lower mileage have been the Chrysler mini vans. It is also mandatory that we use Mobil 1 in our company cars and change at 10K mileage intervals.