klwehunt

I have a 08 c6 a6 that i bought back in March,on cold start it makes a noise until the oil temp gets up to about 80 degree's and it goes away.The car has an A&A kit long tubes cat bacs 66,000 miles.Just noticed the noise as the weather has got cooler and just changed the oil.Thanks for any thoughts KLW.

enventr

It's hard to diagnose without hearing the noise but I would check the exhaust bolts. One of my cars had a ticking noise when it was cold. After awhile after it warmed up it went away. The reason was one exhaust manifold bolt was loose. I tightened it and the noise went away. Let us know your findings and good luck

Corvette_Ed

You're awfully vague about what kind of noise you are hearing. How about expanding on that a bit?

klwehunt

First thought lifter noise but i can hear the noise more from inside the car and underneath with drivers side door open.It also is very minor at idle.Makes louder noise 1200 1500 rpms and above.Goes away at about 80 degree's oil temp.Not sure if it is an oil temp issue or a time frame issue as far as the noise going away.Checked header bolts all nice and tight.As soon as i get it off the floor will check other exhaust bolts.

Mike's LS3

Interesting, I have a similar knocking noise at cold start up and can hear it more from inside the car and underneath with drivers side door open. I also have an 08 with an A&A kit and now 73k miles, (11k miles with S/C). I had the car de-carbed by Abel Chevrolet injecting a chemical into the spark plug holes which blew carbon out at start up. This has reduced the noise. We were thinking carbon buildup on the ring lands possibly causing a piston slap type noise until warm? Since then, I had the car retuned ( it was rich at WOT) and installed full Z06 exhaust. The noise has almost disappeared, but on colder days you can sometimes hear it.
I do remember a few years ago, before the S/C install, I had a similar noise at cold start up. My car was basically stock (CAI) and I added two treatment of BG44k power enhancer in the gas tank to remove carbon build up and it worked.

Other than that, my car runs great!

extrapilot

Need to get a audio clip of the noise. Most still digital cameras can take short videos with sound.

klwehunt

Follow up on cold start engine noise.Talked to corvette guy at the local dealer,he ask if i had changed plugs and i had so went back through them to make sure they were tight.That made a small difference,also changed oil and filter added a half a quart of Marvel Mystery oil and no more noise at all.I'm thinking maybe a lifter was not pumping up just right and the MMO cleaned it up.Was not sure about running it in the LS3 but have used it in lots of other stuff for years noise gone happy camper.