chattering

[swoop]

I own an 07 Denali . It has the 6.2 litre. I bought with 24,000 miles, with 51,000 now. Since I have owned it it has on occasion had a annoying start issue. What is happening is, either piston slap or I have valves chattering. It is loud enough to hear while driving. I try and keep out of the gas pedal until it warms up enough to go away. Once the temp guage gets above 150 or so it gets quiet. Then once at 220 it will go away completely. I'm not sure what it is or if it is cause for concern. But it is the only vehicle that I have owned that has done it. Anyone want to shed some possible light on it?

 

[GM Customer Service]

I own an 07 Denali . It has the 6.2 litre. I bought with 24,000 miles, with 51,000 now. Since I have owned it it has on occasion had a annoying start issue. What is happening is, either piston slap or I have valves chattering. It is loud enough to hear while driving. I try and keep out of the gas pedal until it warms up enough to go away. Once the temp guage gets above 150 or so it gets quiet. Then once at 220 it will go away completely. I'm not sure what it is or if it is cause for concern. But it is the only vehicle that I have owned that has done it. Anyone want to shed some possible light on it?

Hello,

I do apologize for the troubles that you are having with your vehicle. It appears that you may have the powertrain warranty on your vehicle still. I would suggest taking it in to the dealership and having them take a look at it. Sounds like it may be a powertrain issue. If there is anything I can do to help, please let me know.

Geoff Allen
GM Customer Service

 

[mike1944]

If I let my Deanli sit for a few days it will make a pretty loud noise that I always associated with tappets - might be something else.

After it warms up it goes away.

Won't do it again until it sits unused for a few days .... again.

 

[mike1944]

Found this on a chevy forum.

Synthetic oil has better flow characteristics when cold as well as hot than conventional oil. If it can flow in better, then it can flow out better as well. I think that this is why engines with cylinder deactivation have this lifter noise at startup. The mechanism that allows this function also allows oil to drain down overnight, or several hours. When I test drove my Yukon XL, it was 10 degrees F. outside. When I picked it up it was the same outside temp., and heard no lifter noise at start-up.

Everything was fine for first 3 weeks until I decided to treat my engine to Mobil 1, then a day or two later I thought I was hearing things in the mornning at startup. Sure enough, my almost new engine was sounding like an old clapped-out GM when started after a few hours, clack,clack,clack,clack, for a second or two.

The duration of this clacking, got longer each day, until it was maybe 3 or 4 seconds each morning. This was driving me crazy. I was standing outside the vehicle at each start just to confirm what I was hearing.

Then it hit me. Maybe it was the synthetic oil draining down. Went to dealer and told them to change oil and filter again , it's my money, humor me. Next day, no lifter noise.

 

[KMeloney]

I own an 07 Denali . It has the 6.2 litre. I bought with 24,000 miles, with 51,000 now. Since I have owned it it has on occasion had a annoying start issue. What is happening is, either piston slap or I have valves chattering. It is loud enough to hear while driving. I try and keep out of the gas pedal until it warms up enough to go away. Once the temp guage gets above 150 or so it gets quiet. Then once at 220 it will go away completely. I'm not sure what it is or if it is cause for concern. But it is the only vehicle that I have owned that has done it. Anyone want to shed some possible light on it?

I had this with my '02. The dealer asked what octane gas I was using. When I said 89, he asked why I wasn't using 87, and said that I should be. Whereas I don't recall it being a very appropriate response, I used 87 from there on out, and I don't recall having the problem for too long after (although I did continue to have the problem initially).

 

[deangrell]

I have a very loud significant clapping noise that sounds like something stuck in a fan...is this what we are talking about? I haven't heard it in awhile, but my best description would be to have a fan on, and put a wooden spoon into the blades. It's about that loud...and it only lasts about 3-5 seconds on startup.

 

[swoop]

Thank you guys for all the insight. It is intermittent. Some days when it is 40 out which is not that cold it will do it even if I have driven it that day and let it sit for a few hours. Other times it can be even colder and and not make any chattering noises. I do have the 100,000 power train warranty. So thats good. I was at the dealer yesterday on another weird episode with my Denali. The vehicle remotes stopped working. Both of them. Tried reprogramming them several times with no success. Dealer checked them out and said that they had a weak signal. But the odd thing is if I open the door with the key and then use the remotes I can lock and unlock. Even remote start it. So after searching the Internet for new remote FOB's, I ran across a tech. article that said even a new remote will not work if your vehicle has a check engine light on. Well my Denali had a electrical gremlin a couple of days prior and the service stabilitrack message appeared in the DIC. Followed by a solid engine light. Well I went through the process of shutting down and letting it sit per owners manual instruction. And the message went away along with the solid engine light. "BUT" there must have been a code stored because after I removed the battery cable to clear the computer yesterday to see if that was keeping my remotes from working. They did indeed work after hooking back up. Go figure. Sorry for the long winded story.