Question about 2000 BMW M5

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Bmw air injection pump problem...HELP!

I have a 2000 bmw328i and when I first start it up in the morning... it has a loud screeching sound on the outside, and in the inside it has a suction sound. But then after about 2min the sound goes away and the car drive fine.... there are no check lights on. when I apply pressure on the secondary air pump the frequency (high pitch noise) changes.... I also have a small exhaust leak... does anyone know if this could be where the noise is coming from if so... is it hard to fix...or could I just bypass it....and it is not a belt problem

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I read that the SAP is for supplement air feed when the engine is cold, typically winter conditions starting the car after it sat over night chilling. The SAP comes on after several seconds and runs for about 1/2 min to 2 minutes. It's job is done. This is why can make noise on cold start up for only a couple of minutes.

The SAP is a black flat disc shape. With older BMWs, it isn't uncommon for 2-3 of the 6 rivets that hold the housing together to get loose or fall out. The fix is to remove the other rivets, take the SAP apart and clean it. Then reassemble with good fasteners.

If diagnostics indicate a problem with the SAP system and it isn't the SAP, it could be a faulty/dirty check valve. You've probabaly already fixed your problem from 5 years ago, but this is still an on-going gremlin for many even today.

Posted on Mar 19, 2013

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Sounds like the secondary air pump has water contamination. If you unplug the connector for the air pump, and check it on cold start, did the noise go away? If the pump is bad, you need to replace the secondary air valve. Sounds like maybe it is contaminated and not seating fully.

Posted on Mar 09, 2009


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