Date: Thu, 15 Aug 2002 21:51:50 -0700
Reply-To: TinkerMan <tinkerman007@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: TinkerMan <tinkerman007@YAHOO.COM>
Subject: DIY / Homemade coolant system pressure testing
Content-Type: text/plain; charset=us-ascii
Hello Volks!
Following a recent coolant hose rupture probably as a
result of excessive coolant pressure due to radiator
fan resistor failure, I have decided it was time to
devise a method to check that coolant expansion tank
pressure release cap and cooling system in general,
whenever I wanted to (and not having to go to the
dealer just for that).
AFAIK, that pressure release cap has a 15psi threshold
that releases extra pressure into the coolant reserve
tank and sucks coolant back when vacuum inside cooling
system increases above about 3psi (it's a dual
threshold device).
In lieu of a commercial VW coolant system pressure
test tool, which has adapters for testing both the
cooling system as well as the cap, I've thought of an
extremely lowcost method to test the above.
I was thinking of connecting a lowcost bike pump with
integrated gauge (I already have) to the cap union
(the one that goes to coolant reservoir). Of course,
there would be some inherent inaccuracies due to the
pressure drop across the cap pressure valve, but
still, I would be able to check for cooling system
pressure leaks and test pressure release valve
functionality (both ways) in an approximate fashion.
What I'm concerned about is possible damage to the
expansion tank cap pressure release valves due to
non-standard operation of the cap (normally, it never
experiences appreciable back pressure from the coolant
reservoir. Here is my test procedure:
1. Disconnect hose from coolant expansion tank cap
(easy).
2. Connect cap union (is that the right term?) to the
gauged bike pump with adapter.
3. Slowly (and carefully...) start pressurizing the
cooling system. Verify that air starts to go into
system at about 3-5 psi max (tests the reverse valve).
4. Continue pressurizing the cooling system to about
20psi (15psi maximal permitted pressure PLUS reverse
valve threshold of about 3-5 psi).
5. Stop pumping, and look for any leaks in the coolant
system (this time without motor running and hot
coolant squirting around...). Make sure that pressure
on gauge doesn't drop over time due to leaks.
6. disconnect pump from cap union, and listen to some
air going out due to 15psi pressure release valve
activation (now that the reverse back pressure has
been removed, the 15psi release valve goes into
action). Not much air should go out, because we had
only a few psi over 15psi).
7. Release pressure by removing cap, and topping off
if necessary.
My questions:
1. Anybody been doing this already with good results?
2. Any foreseeable damage to the cap valve mechanisms
due to these games?
3. Any other suggestions?
Due to our waterleakers being extremely vulnerable to
coolant leaks, I think the above test procedure could
help safeguard us from unexpected failures along the
road, which as always happen at the most unexpected
times...
I welcome your comments and suggestions.
=====
Cheers, T-man.
__________________________________________________
Do You Yahoo!?
HotJobs - Search Thousands of New Jobs
http://www.hotjobs.com
| 
