Secondary Air Injection

[cook28]

I'm familiar with the purpose of the system but recently during warmup the whistling has been getting louder until it shuts down. I know there is a filter that sits at the very top of the unit which is enclosed, can the top be removed and the filter be changed or does this come as one unit only?

Thanks
cook28

[Jeron]

This is an E36?

I have never taken mine apart, I did not think there was a filter.

I would check the in and outlet hoses for restriction. Are you sure the noise isn't a bearing?

[cook28]

E36 328i, sure enough, I removed the upper hose that appears to just be a vent because it connects to nowhere and looked inside with a light an noticed this small circular filter. I think the the other hose coming off this part runs to the EGR. I guess I'm more curious if the whistling sound on cold starts is a normal thing.

[Jeron]

The upper inlet hose doesnt go anywhere. The outlet should go to a valve then to the exhaust manifold.

It should sound like a blow-drier on cold starts for about 1 minute, then go off.

[cook28]

I think were ok then. Thanks!