Most all Audi VW thermostats are the dual disc types. This is a special
design as this is actually being used as a mixing valve. None of these
should have a bypass or bleeder. Single disc stat designs need the bypass so
that hot coolant from the engine can flow to the stat so it can open.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of C
B
Sent: Friday, June 04, 2010 1:28 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Rich Running Chilly 1.9l WBX

Hopefully I have found the culprit, a thermostat both failed and
incorrect to begin with.

Dennis gave me a precise description of the *correct*, plain 87 C
t-stat, which *no bypasses or relief valves* (t-stats that do are for
other Audi/VW applications, not Vanagons). Mine, which I unwittingly
installed after a water pump replacement soon after purchasing the
camper, has a small ball-valve bypass, which has failed open. This
explains why Cunegonde usually ran cool, and then below operating
temperature with the failed t-stat. I expect her to run warmer now
(report after test drive).

TECHNICAL NOTES
Even with the rear of the van up on stands, at least 2 gallons of
coolant will need to be drained from the overflow tank and engine
compartment cooling pipes
I used a 5-gallon tub to drain and catch coolant.
The t-stat housing is fastened to the water pump with 2 long 10mm bolts.
Work from underneath for the t-stat housing bolts, above for the
water pump bolts.
The front bolt can barely be accessed with a 10mm deep socket,
preferably with the oil filter removed
The rear bolt only fits a regular socket or flat closed ratchet
Once the bolts are removed, the t-stat housing *with the t-stat
installed* *will not clear the exhaust header*
Don't forget to lube the o-ring (perhaps with something water-based,
ahem) and also the bolts (I used a touch of clean 10w-40)
I ended up loosening the water pump to get the t-stat housing back on
with the t-stat in place so as not to damage the t-stat O-ring
And... re-fill and bleed the cooling system when all is back in place

Total time, about 1.5 hours not including a second bleed.

--
Brett's

1983 1.9l WBX Ivory Westfalia "Cunegonde"