[s-cars] Pressure Test

[Ian Duff]

Sounds plausible. You might want to get a pressure regulator for your air
tank, with two intended results: 1) allowing air tank to hold full pressure
and automatically, continuously allowing only the pressure you want into
system, and 2) staying in wife's good graces by virtue of not needing her in
cold, drafty garage.

A regulator configuration like this would allow you to pressurize to
whatever pressure you hear the leak, then with the regulator pumping in just
a little more pressure, snooping around until you discover what's leaking.

HTH.

-Ian.
-----Original Message-----
From: s-car-list-admin at audifans.com
[mailto:s-car-list-admin at audifans.com]On Behalf Of Ed Walsh
Sent: Sunday, 27 April, 2003 9:40 AM
To: s-car-list at audifans.com
Subject: [s-cars] Pressure Test


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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