[V8] Exhaust re-installed, but now we have vibration at idle

[urq]

If you still have the factory exhaust there's no need to get anywhere near
the engine/transmission to mess with the exhaust.  Audi installed sleeve
couplers between the cats and the remainder of the exhaust ... 

It may be that the exhaust is not now positioned properly and is contacting
the body somewhere, but based on your report I'd look for the engine or
transmission touching the subframe or body somewhere.  On the urq bad motor
mounts caused the oil pan to touch the subframe and make that sort of noise.
You have two options, one is to crawl around under the car and check
clearances between the drivetrain and the body, or to check the motor mounts
specifically.  On the V8, the torque snubber mounted up near the alternator
can be a tell tale ... if you find that the rubber mount up there has
separated, it means that one or both of the motor mounts have collapsed.  

Steve Buchholz

-----Original Message-----

This local shop just welded a new center section onto my very loud  
exhaust.
They had to remove the exhaust to do it, and muttered something about  
removing engine mounts to get the exhaust off.
I just picked the car up, and now I have this vibration of the whole  
car at idle that I'm sure wasn't there before.
I haven't had a chance to look underneath, but what mounts were they  
referring to? and how could they mess up the re-attachment?
There's no clanging sound or anything, just a pronounced higher  
frequency vibration throughout the car.
When I accelerate, it diminishes.

Mark.
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