Hodgie

I have a 2004 A4 3.0 and when starting a cold engine I often get a bit of a rattle from the engine for about half a second once it starts up. If I restart the car after the engine is warm it's a smooth, quiet start. Anyone else experience this?

akula-ssh

How cold is cold? I'd say that's abnormal, unless you're running a very viscous oil. Also, what kind of rattle is it?

wailshark

What oil do you have in there?

Almost sounds like the cams aren't getting enough oil to them and that they're knocking against the valves until the engine warms up.

Hodgie

I always use 100% synthetic oil, changed every 7500km. By "cold" I mean when the engine hasn't been running for a few hours. It's a very brief rattle or knocking sound then it's smooth. I decribed it to the dealer and they said it had to do with the oil pressure in the crankcase and that it was characteristic of the 3.0. I still have a few months of factory warranty.

akula-ssh

What's the weight of the oil? I wouldn't say it's a "characteristic" of the 3.0, for I don't have that. I do hear more valvetrain chatter (i.e., more diesel sounding) before the engine warms up, which I consider normal.

Hodgie

Thanks for your input. Not sure what you mean by the "weight" but it's Castrol Synthetic 5W-40. I've topped up with a 0W-30 on occasion too. Interestingly, before I bought this car I heard the same start-up noise on another 3.0 that I test drove. I even found this on a you-tube video that another 3.0 owner recorded!!! (see YouTube - Normal Starting Noise Audi A4 2.0T). This leads me to believe it is inherent in the 3.0 engine. I've heard it has something to do with the cam chain tensioner waiting for the oil to pump up. Make any sense? Any other 3.0 owners hearing this sound on a cold start?

Thanks!!

akula-ssh

5W-40 is a perfectly good weight to use in our 3.0, so that shouldn't be a problem... It's always possible that what you consider a rattle I think of as merely valve train chatter. It's certainly reasonable that it takes a short amount of time for oil to circulate up to the heads, but to have so little oil left prior to startup that a rattle or knocking can be heard is, to me, a bit disturbing.