blowing exhaust on start up

[tinman1.8t]

Hi all! wondering if anybody has had this problem?
my 2002 1.8t avant sounds as though the exhaust is blowing (around the manifold/turbo area) on start up. after 20 - 30 seconds the blowing stops. if i switch off the engine and then restart it there is no blowing, therefore it appears heat related.

any ideas?

[Dave Avant]

Cracked manifold? Could also be a leaky joint. The heat will seal it as you said. Check all the joints and nuts for a leak and tightness. Might eaven see a crack/blackend joint where its leaking from.

[Crasher]

The secondary air injection system can make them sound odd and it shuts off if you turn the engine off and then re-start. Have you owned the car long?

[tinman1.8t]

had the car 3 1/2 years. definatetley sounds exhaust related. blowing stops while engine is still running so doesn't give much time to locate noise.

[Crasher]

It sounds like a problem in the secondary air injection system and that runs for about a minute.

[tinman1.8t]

don't suppose you know the best way to investigate this? will i damage the car using it with this problem?

[Crasher]

What is the engine code, do you have a registered copy of VAG-COM?

[tinman1.8t]

excuse my ignorance, but i don't have cag-com or know the engine code.

thought i'd sorted it friday as there was a pipe off under the air filter inlet tube. i reattached it and left the car to cool down. started it later and the noise is still there, however much quieter, and again it went off after 30 seconds to a minute. sounds like the noise is coming from back left of the engine above the turbo where some pipes go around the rocker cover and into somesmall 'housings'. noise stops instantly like a valve or switch has closed

[Crasher]

The pipe from the SAS pump may have come off the valve on the back of the head.