He would have to mean at the airbox connector to test the connections he mentioned... which is how the Porsche factory service manual calls for testing.

It's like a valid point to look for possible cracks and leaks pre-turbo, but I personally would still do it after I've tested and fixed all post-turbocharger leaks if you don't want to be chasing your tail hunting down phantom leaks (like through the turbo oiling system).

Also, everything pre-turbo is at ambient pressure or vacuum, never pressurized. You could probably test that section effectively at much lower than 1 bar.

 

...I see Kevin clarified while I was still writing my response. This sounds like the best course of action for a completely thorough test, though I think F pipes, diverters, check valves, loose hoses on the vacuum/pressure switches, etc. are much more common failures and all will be found fairly quickly when testing at turbocharger inlets.

 

 

I don't know if it causes damage to the seals, but it seems fairly common to have a bit of leakage into the oiling system when you pressurize pre-turbo....

But no doubt if you pressurize, and keep increasing the pressure on systems beyond their intended environment, you will eventually hit a failure point.

 

Turbocharger seal damage?? I see 4.5 to 5 bars of oil pressure on one side of the turbocharger seals>>don't you?? That's why the first sign of turbocharger failures (other than FOD damage) is oil in the inlet compressor side.. The oil pressure pushes oil past the worn sealing ring!! 1 bar of intake pressure won't damage the turbocharger seal!! If it does, one needs a turbocharger rebuild.

 

 

Thanks Kevin.

 

great info/thread.

i've tested my car at the turbo inlets many times. never *not* found a leak ( if/when i had one ). as for inlet piping above? just give the intake hoses a good tug after any r&r. never a problem. boost leaks are more common on poorly maintained cars, than not.

 

So pfbz lives 5 minutes from me and was kind enough to come over and help me with the some boost leak testing. Found a large leak on the bottom of my passenger side O ring connection, probably caused by me not seating it completely when I'd put it back together after doing the spark plugs/coil packs.

With that fixed the car now held pressure fairly well, with a 2 psi drop within 30 seconds starting at 15psi. There's an audible leak that isn't bubbling with soapy water spray, it sounds like its coming from the Y pipe to tbody connection.

I ran out of time to drop the motor and investigate further so my plan is to order the Y pipe O rings and a few check valves that are in that same area, drop the motor, replace that stuff and pressurize it again and see what happens...

 

that area atop the the t-body plenum area is where the infamous #16 check valve sits, and it is cheap and plastic and prone to cracking. then it *hisses" with escaping air under a proper pressure test. cheap part to r&r and famous for being the source of "leaks".

 

Yup, I believe that's one of the check valves I plan to replace.

 

its *usually* the culprit. GL w it.

 

Actually, it didn't appear to be the #16 check valve, at least not leaking in the way I'm used to them leaking, which is down the pipe to the drivers turbo intake...

Might be the small black and white check valve that also comes off the plenum, or the TB gasket,, or the suction valve... Need further listening/spraying/lowering engine but ran out of time. And the suspect parts are cheap, so it makes sense to have some of them on hand before going too much further

Some part numbers for Josh and others:

• #16 Check valve 996.110.135.70 - $27.30 -
• Boost hose o rings 996-106-801-06 $5.65
• Check valve black and white small (qty 2) 964-110-950-02
• Throttle body gasket 996-110-318-02
• Suction jet pump (aka venturi tube) 996.110.652.70

 

didnt realize the others were actually called check valves. in either event, the one atop the plenum is the only one i've ever had to deal with.

in other news. that guy is lucky to have you as a neighbor lol

 

These are the small check valves... I don't know if they ever cause massive leaks like the #16, but one of mine was definitely leaking when I went through my turbo plumbing last year.

Bad:




Good:


This picture shows one of the two small check valves coming off the plenum... The other one is on the line that goes to the diverter valve controller. You can also see the throttle body o-ring that often leaks...