Exhaust sound coming from smog pump, normal?

[smcmanusx]

'97 Z-3 2.8 just installed the new secondary air pump as the old one froze up. The new pump works but I'm getting an exhaust sound from the pump after the pump shuts off. I pulled the hose off and the noise was coming from there and it felt like there was vacuum on it. So what else needs replacing now?

Thanks
Steve

[Bob S.]

The pump that is sitting by the firewall is an air injection pump which pumps fresh air into the exhaust manifold at times when the engine is still cold, leaning out the exhaust gases by helping the cat run a "second burn" of the exhaust. If it is this pump then you should check the Vacuum Control Valve [P/N 11 72 1 744 255]located just off of the exhaust manifold. It's where the hose from the air pump runs to.

Hope this helps.

Bob S.

[s-retire]

That might be why the first pump failed. Don't let it go unchecked for very long.

[smcmanusx]

Thanks guys. I'll cork the hose up and pull the plug on the blower until I can get a new valve in there. I had heard from some other folks that they'd replaced the secondary air pump a couple of times so I figured that 14 years and a hundred thousand miles might have killed it. It does make sense that exhaust flowing back through the blower could ruin it.

Have a nice day
Steve

[smcmanusx]

I put the new valve on and that fixed it! Thanks for the good advice.

Will the check engine light go back out after x number of cycles, or do I have to reset it?

Have a nice day
Steve

[@ bimmer2.8]

should go out after x number of cycles, cold cycles.