Hi,

I just bought a 2004 A6 2.7T about a month ago. I have noticed that when I start it from cold it makes
a noise similar to an exhaust leak. It only lasts for a minute or two and then sounds normal. Is this normal
for this car or is it an exhaust leak? I was thinking something wasn't sealing properly when cold but would
seal itself after slight warm-up. I don't know if I should bring this in for service or not.

Any help would be appreciated.

Thanks
Stan

 

Hello,

My 2004 Allroad 2.7T has always done this and it seems to be normal. I believe my 2000 S4 did it also.

 

That noise you are referring to is most likely from the operaton of thesecondary air injection pump.It normally operates for less than 2 minutes immediately after a cold start. Its purpose is to start the warm up of the exhaust catalytic converters soonerby injecting fresh air into the exhaust system before the pre-cats thus adding more oxygen into the exhaust gas stream via a one way 'combi valve'attached tothe cylinder heads at the rear of the motor.

Enjoy!

 

the three 2.7T I have driven all do it. Tjis engine is real rough when cold and sounds like a tractor but I love it!!!