|Since I recently got the car running I've been trying to hunt down a nasty boost leak. Did a boost leak test and there was a clearly audible sound from the around the passenger side of the plenum that I couldn't isolate. I first started with the usual suspects (intake clamps, vacuum hoses, PCV, balance tube seals, etc). That didn't solve it, so I went deeper. Removed all the passenger side intake piping and as I would add piping back in I'd pressurize that section. No issues there whatsoever. By process of elimination I figured the next possible leak must have been the intake vale cover since I recently removed that during the engine pull. So I pulled the plenum, resealed the valve cover and got the the intake system all buttoned up to re-test.
The leak persisted! Motherfu...
At this point I was probably on my last nerve. I was starting to think it was leaking from the spark plug tubes in some way (highly unlikely), but as I was fishing my fingers around I stumbled on the issue. The plenum itself.
Side note: I picked this up from someone since it was already powdercoated and my local shop was closed due to the pandemic. So, the PSA here is that if you buy a used plenum, be sure to look it over before installation. Check all the threads, even those you might not think you actually need to use.
Back to the story...Pulled the plenum AGAIN but now with insight as to the source of the leak.
It was right where I'm pointing to in the picture. These standoffs are meant for the coolant hose hardlines. Air doesn't flow through those at all, but for some reason this one was pierced through.
The bane of my existence right here.
Luckily the threads themselves were still good, so a bit of teflon tape on a bolt and sealed it shut.
It's moments like these I appreciate the 300 degree fuel rail hose routing. I was able to pull the plenum without having to open the fuel lines. Pressure was purged anyways just as a precaution, but being able to just move them out of the way is very helpful.
Also, pulling / re-installing the intake valve cover was super easy with the BDE studs.
All buttoned up again and finally holding pressure!
To celebrate the win, drove down to the waterfront yesterday. It was the first proper drive of the season having the leak sorted out and the new shoes on. Snapped some pics while there. Enjoy!
Reminds me...I should probably update my signature at some point...