I've got an exhaust leak coming from under my UIM. The smell is accompanied by a the standard pulsating gurgle. I've also noticed the airpump moo is a lot louder than before this leak started when coming off-throttle.

I'm thinking ACV or EGR but I don't really know how to diagnose these short of tearing things apart. Any suggestions? Anything else it could be? Almost positive it's not turbo/downpipe related as I used the old pipe-to-ear method to probe around the engine bay and the sound is loudest right under the UIM.

Thanks!

 

do you mean a vacuum leak?

spray brake cleaner and listen to the idle. If it drops, you've found your leak.

 

U can use a propane mini-torch to check for leaks as well. (don't light it) if idle increases you found your leak.

You're probably right with the ACV though since it's tied into the exhaust, nothing else under there except the PCV is connected to the exhaust system.

 

Not a boost leak, definitely exhaust. It's obnoxiously loud and once boost comes on you better be holding your breath.

 

ACV. last one i saw, the check valve behind the ACV fell out of its groove before the valve went back on.

 

Okay I guess the UIM is coming off :P I just put it on too. Weirdest thing, dropped the new motor in, ran great for 80 miles, then the exhaust leak started. I never touched anything on the LIM. What are the chances?

 

you should be a pro at removing the UIM by now...if not consider this practice and a chance to give everything else a good look over. I can do it in less than 10 mins.

 

Heh yea, but I just put the damned thing ON when I re-did everything that I thought was important on this new motor while it was still on the engine stand. Not the ACV gasket apparently ;P

 

Problem solved! It was indeed the ACV. When I pulled the UIM, I found that there were exactly zero nuts holding the ACV in place. One was sitting nearby. They must have been only on finger tight on the motor I bought. I assumed there would have been no reason to remove the thing so I never checked to ensure they were fully tightened :P

Thanks for the help guys!