Thermostats don't prevent overheating, they make sure the engine reaches a
certain operating temperature. And at 90C, a 80C thermostat is just as open
as a 87C thermostat! In other words, a lower temp thermostat doesn't solve
an overheating problem because your engine is way beyond either thermostat's
range when it's overheating.

But that doesn't keep misinformed people from trying and I see the practice
over & over again. My 77 Vette had a 140F thermostat installed when I bought
it and the car would overheat at long idle. It would actually spit-up
coolant at long traffic lights. I chased the issue down to a leaky radiator
cap that would not keep the cooling system pressurized. I replaced the cap &
installed the correct 152F thermostat and it hasn't overheated yet!

Most causes I've seen for overheating have been a slow leak, a leaky head
gasket, engine timing and a plugged radiator - it's surprising how few
radiator cores need to be plugged before you have an issue.

Also the only thermostats I've seen fail have failed open, not closed.

Tom
www.kegkits.com

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf Of
Scott Chapman
Sent: Wednesday, April 14, 2010 8:13 PM
To: vanagon@GERRY.VANAGON.COM
Subject: 80c or 87c thermostat?

I see that there's lower temp thermostats avaialble for the Westy.
What's the use of a lower temp thermostat?  Stock is 87 and these are 80
IIRC.