I've got a 2005 GMC Envoy with 4.2L 6 cylinder with 54K miles.
I recently noticed a high pitched whine that starts up when I start
the car cold and then winds down after about 20 seconds. It sounds
like some bearings failing in a motor some place.
I took it in to my local mechanic to look at he and he says I have an
exhaust fan inside the exhaust system and a check valve that prevents
vapor flow back into the engine on start up and that the valve and fan
have failed.. and that it's about $600 for parts and labor to replace.
Anyone ever hear of such valves and fans and know anything about them?
He says it's just below the drivers door which is why I noticed it so
Thanks in advance for any info.