# 1999 Audi A6 2.8l subtle idle sound a little like a diesel



## Michael Peanuts (Jan 29, 2010)

It's Got 160k on it. I just got it. Please tell
Me its not catastrophic. Could
Fresh oil and tbelt change fix this?


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## O_o (Nov 12, 2009)

These engines make a fair amount of valve noise, especially when first started after sitting for a while. Let it run for a few minutes, and if it doesn't quiet down, come back and let us know.


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## Michael Peanuts (Jan 29, 2010)

Thanks, its really when its completely warmed up. Inside the car, it idles beautifully smooth, in fact it runs terrifically. Its only when i step outside that i hear this. Its due for an oil change so that will be done extremely soon. Aside from the cat related CEL and the usual C5 quirks the car is the best I have had.


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## O_o (Nov 12, 2009)

Yeah, if you can't hear it in the cabin, I wouldn't worry too much about it, unless you hear that there is a valve in particular that's tapping.

See if you can find somebody with the same engine, and compare.


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## O_o (Nov 12, 2009)

I forgot: the other possibility is that the cam-chain tensioner is going. Do a search for youtube videos of CCT noise, and see if it's the same thing.


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## Michael Peanuts (Jan 29, 2010)

Thanks a lot for your input. I have been reading about that and when I get the CEL taken care of I will look into that and its replacement (if necessary).

Would a heavier weight oil be advisable? I live in AZ and my old MK2 GTI was using 20w50 versus what the manual called for.


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## O_o (Nov 12, 2009)

It depends. If the lifters are worn a heavier oil sometimes helps, but if it's gunk preventing the lifters from getting enough hydraulic pressure, then a lighter oil might help.

However, I think I might be confusing you. Because I forgot about the CCT initially, it kind of reads now like it's an afterthought, a "maybe also". But really, that's the most likely source of unusual valvetrain noise, especially since you describe it as sounding like a diesel. In other words, it should have been the first thing I thought of.


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## Michael Peanuts (Jan 29, 2010)

Understood. Googling the CCT shows it to be fairly common. I will look into that for sure.

Thanks so much for your input, I am extremely thankful for your advice.

:thumbup:


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