[s-cars] Pressure Test

[Ed Walsh]

Some may know, ad nauseum, that I have been trying to
fix a lower than expected max boost issue.  S6 MTM 1+.
 (stumble appears to have been fixed my BM's MAF)

It was recommended that I try to pressure test the
motor to see if I have any leaks (minor ones that
would appear only under boost).  Well, after testing,
I think I might....

I made an adapter out of a 3" male sewer clean-out cap
(great tip!), for the hose that attaches to the MAF.
I installed an air compressor quick connect adapter
thru the cap.  All is air tight.  Here is what I did
the perform the test, tell me if I am doing this
righto:

- Told wife she looked nice today and that I was
looking forward to her parents next visit
- Pressurized my 2 gallon portable air tank to ~20 PSI
- Ask wife to help me read the boost gauge in my car
:)
- With wife/eyes in place, Connect quick connect to
home brew adapter, pressurizing the system.

My suspicion is/was that an air tight system would
hold these 20 PSI and that it would indicate this on
the boost gauge.  No?

- Wife reports that, not only is it cold and boring in
the garage, she only saw 2.5 PSI after I pressurized
the system.  After about 10 seconds, the pressure on
the gauge actually rose to about 3.5 PSI.  Weird?
I'll explain.

- When I initially connected the air tank to the
adapter/cap, I heard a deep rush of air being moved.
(like a jet engine heard from 30,000 ft below). I had
thought this was just the system being pressurized,
but it appears that the noise was from a leak.
Where?, I don't know, but the sound seemed localized
in the under the turbo area (crossover pipe?)

I couldn't feel or see any air leaking, but it had to
go somewhere... Or am I screwing the test up?

I hypothesize that the reason the pressure actually
rose to 3.5 PSI after about 10 seconds
(coincidentally, the same amount of time I heard a
deep rush of air being moved) was the result of the
leak re sealing itself.  It would then hold that 3.5
PSI for 30+ minutes.

So, as long as I have done the test right, I may have
figured this out.  Can anyone confirm the test is
accurate b4 I battle hell's gate (the belly pan)?

Thanks a Million,  Ed


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