Chasing Vacuum Leaks

[Mike_Buckham at ptk.pioneer.co.uk]

LL,

(1) and (4) I used an electric tyre pressure pump this weekend which was
attached to the intake port where the hose to the ECU sensor is usually
attached. I disconnected the big fat metal tubing from the boot over the
airflow sensor plate (the other end of which goes to the turbo intake) and
pressed my hand over the end. I was able to pump up the system and very
quickly detect if there were any leaks (of which there was one).

(2) I managed to patch mine. It used to rub against the crank pulley when I
bought it and it made a hole. I cleaned it up then patched it with 3 layers
of repair products: firstly water hose repair tape, then aluminium exhaust
repair strip (very flexible and sticky, like stiff tape) and finally with
some PVC insulation tape. It made an extremely secure and air tight seal
and has cause no problems at all.

(3) I believe that the default state for the wastegate frequency control
valve is to let air into the top of the diaphragm from just before the
inlet of the turbo. If your diaphragm was leaking, then intake air would
end up back to just before the turbo and cycle round the intake system.
This would cause problems with the intake pressure and also with the fuel
mixture.

Cheers, Mike.

=====================================================================

Message: 15
Date: Mon, 19 May 2003 13:05:59 GMT
To: quattro at audifans.com
Subject: Re: Chasing Vacuum Leaks
From: l.leung at juno.com


Patient (as I'm not...anymore) '89 200Q - Chipped 1.8 Bar

Symptoms - hissing under boost, max boost about 1.3 bar definitely  leaking
=
 boost SOMEWHERE. Car cuts off power if boost demands get higher
than moderate (not gentle) acceleration. RPM not dependent. Didn't have tim
=
e to recheck using the dipstick test, but it did fail prior to my temporary
=
 patch.

Probable cause - leak. In the time availible, I've checked all of the vacuu
=
m hoses, MM hose, ISV hoses manually. Rechecked valve cover gasket. Did fin
=
d one hole in the "T" breather hose on top of the valve cover, fixed a temp
=
orary patch with rubber tubing and a hose clamp. (part will be ordered toda
=
y). SO, it's down to the lower IC to Turbo hose (yeeesh, $$$) or the IC its
=
elf. Or it COULD be the boot over the airflow plate, but that is new as of
=
last year.

Question 1 - how do you check the IC for leaks?

Question 2 - where are good sources for lower IC hoses?

Question 3 - could a torn WG diaphram cause any of these symptoms (I don't
=
believe it could, as it's not in the intake stream, right?)

Question 4 - HOW or more precisely, WHERE does one hook up a MityVac to hop
=
efully cause enough vacuum to cause enought noise so that I can find this s
=
tinking leak?

TIA!

LL - NY


This e-mail and any files transmitted with it are confidential and intended solely for the use of the individual to whom they are addressed.
If you have received this e-mail in error please notify your system manager.

Please note that any views or opinions presented in this e-mail are solely those of the author and do not necessarily represent those of the company.

Finally, the recipient should check this e-mail and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this e-mail.