I was heading up north for a relaxing week last Sunday and my air diverter valve did a melt down (see pics below). Fortunately it failed about 25 miles into the trip. Engine is a 1989 460ci-EFI, 142000 miles. I took it home and grabbed another truck.

The valve itself looks like a no-brainer to replace, but is there anything else I should check? Is there anything upstream or downstream from this valve that would cause it to fail (I don't want to replace it & have the new one fail)? The valve itself, or valve housing, melted open. There is one hose that is still blowing hot exhaust into the area surrounding the diverter valve.

Not sure if this is related but: I have noticed recently after its warmed up & at just around 20mph it sounds like something (a valve?) opens up and the exhaust tailpipe sound changes by adding a loud jet-like SSSHHHHH that kicks in and keeps going. I don't actually hear anything physically (mechanically) open up...just the exhaust sound gets much louder. The exhaust system itself is a year old. The catalytic converter is original. No holes in either as far as I can tell. This SSHHH exhaust sound never happened until recently...maybe the last few hundred miles.

any thoughts?
thanks

 

Yes, you need to also replace the exhaust check valve at the engine (exhaust) side of the rubber hoses. Thats the reason it melted down in the 1st place.