what is this part, part II, with pics

[kewpie79]

hopefully the pics come through. Can anyone tell me what this part is? It was located to the left of the alternator and had a hose coming off the air pump and the air breather. You can see in one picture that it has melted. i put another part on from a junked car and it melted even worse. Any ideas what this is and why it keeps melting?

http://www.flickr.com/photos/kewpie79/?saved=1

 

[85GPLef41]

I think its a air diverter valve. i have one too and its hooked to the air pump,air injection pipes and the the cats. As for why its melting the only thing i can think of is that its resting on your exhaust manifolds or headers. Hope this helps you some.

 

[85 Cutlass Brougham]

It's definitely the diverter valve for the AIR system. As to why it keeps melting, do you have headers? Do you have manifolds and are missing a heat shield? Is your catalytic converter plugged? Is the heat riser valve stuck in the shut position? (Assuming Small Block Chevy with stock emissions). Is the diverter valve bracket bent in such a way as to make it too close the the manifold? Those are all the possibilities that come to mind for me.

 

[kewpie79]

No headers. Stock engine.

 

[joe_padavano]

No headers. Stock engine.

The diverter valve is melting because the check valve on the A.I.R. manifold (the air injection pipes that bolt to the exhaust manifold) has gone bad. This allows hot exhaust gas to flow all the way back to the diverter valve. The plastic valve body doesn't last too long as a result. Had the same thing happen on my 307.

 

[kewpie79]

how do you go about fixing the check valve? Is it a part that can be replaced?

 

[85 Cutlass Brougham]

The check valve is replaceable. It is what the hose attaches to on the AIR manifold which bolts to the exhaust manifold.

 

[kewpie79]

In regards to the diverter valve, I found two at NAPA. One is with a deceleration valve and the other one without. Which one does the 305 have?

 

[joe_padavano]

The check valve is replaceable. It is what the hose attaches to on the AIR manifold which bolts to the exhaust manifold.

Just be aware that it is very easy to twist the thin tubes of the A.I.R. manifold when you try to loosen the check valve. I had to apply heat to get it to unscrew.