I'm new to the forum, just got a 2008 Tahoe Z71. Had a few weeks now and about 3 or 4 times when I have started the car there is a veryloud grindingsound coming from somewhere under the hood that lasts only couple of seconds. Almost sounds like a mini jack hammer.It's random and doesn't last very long so haven't been able to tell what it is. The car runs fine but know that's not normal for any car.

Haven't taken back to dealer yet since it happens so infrequently couldn't replicate it for them so would be a waste of time.

Any one had this problem or idea what it is? Thanks.

 

Not sure if mine ismaking the same sound as yours....I get like a metallic creeking from under the vehicle somewhere. The best I can figure is the cat converter is hot and expanding contracting making the noise.

 

Take it to the dealer and have then ducument the problem, this just may save your *** down the road some day?

 

Welcome to the forum. I remote started mine the other day and I thought the engine was self destructing. Never did it again. Have no idea what it was but sounded like a fan blade hitting something which is not possible since fans are electric and not even on.

 

Yeah, I have that random rattle or otherfan blade hitting something sound also. Took the truck to the dealer and of course they could not reproduce the sound. They said it might be the sound of metal expanding while warming up - rriigghhtt.... [:'(]

Let us know if a shop actually finds the cause.

 

I've noticed the same sound, I think, as well. Each time it was when we were starting up the car for a test drive. I even asked the sales guy what the sound was because he noticed it too. I think we both agreed it was the A/C compressor making the noise as the engine started up. It seems, in my experience, that they tend to leave the A/C on when they shut the car down so that if they show the car the A/C is on to cool the car down right away.

Anyway, I've tended to notice this odd noise when turning the A/C on some, but not all, of the Tahoe's we looked at.

 

The noise is coming from the A/C compressor, the condition known as "slugging" is believed to be due to liquid refrigerant collecting at the suction side of the compressor. As the compressor clutch engages, the liquid refrigerant is being pulled through the compressor.

There is no fix and the noise does not indicate a problem or failure may occur.

 

Back in the day that condition was caused by an overcharge. Is something else at work here?

 

We have had the same noise coming from our Suburban when we use the remote startup. It doesn't happen every time, but it does happen more often than not when the engine is cold started with the remote start. It makes sense about the noise coming from the refrigerant collecting near the suction side. But at first I did think it was the fan blades hitting the shroud. No wonder GM is going bankrupt. I spend 50K on an SUV and when I start it up it sounds like a piece of $hit car. It's a little embarrassing when it happens. Just make sure it's documented with the dealer so if there is a problem in the future you can make a case.

2007 Suburban LTZ Black
2009 Harley Davidson Ultra Classic Black