Date:         Tue, 10 Feb 2009 17:54:08 -0800
Reply-To:     John Bange <jbange@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         John Bange <jbange@GMAIL.COM>
Subject:      Mocal sandwich plate plus oil cooler equals overcooling
Content-Type: text/plain; charset=ISO-8859-1

Since I've never been happy with the way my oil temps climb above
220degF when laboring up and over hills in my tool and part laden work
Vanagon, I went and bought an oil cooling system. The Mocal 19 row
cooler squeezes in nicely behind the left taillight and gets great
airflow. Unfortunately, I'm now seeing EXCESSIVE cooling. Even after
roaring up the mountain pass at 65mph+ with half a ton of junk in the
back, my oil temp gauge barely manages to break 150degF. Previously,
before the oil cooler install, I'd see almost 225degF after a run like
that. My first notion was that perhaps the sandwich plate thermostat,
which is supposed to close the bypass hole at 180degF, was stuck and
was pushing oil through the cooler all the time. When I got to work
this morning the oil cooler was hot to the touch, so it's definitely
seeing oil flow. I'm wondering, though, if perhaps it's not the
sandwich plate thermostat stuck shut, but that the bypass is too
small. It's not a very big hole, and the cooler is plumbed with AN-10
hoses (a bit under 5/8" ID) which is pretty sizable. I can imagine
20W50 oil being thick enough to create enough of a pressure
differential across that bypass hole that enough oil would be pushed
"the long way 'round" through the cooler, reducing the oil
temperature. Am I over-imagining, or has anyone else ever run into
something like this? I'll likely be pulling the sandwich plate off and
stove testing it in my wife's best cooking pot this weekend to sanity
check the thermostat, but I'm still curious... am I going to have to
install a manually operated flap to block airflow to the cooler just
so I can reach adequate operating temperature?
--
John Bange
'90 Vanagon - "Lastwagen"
'90 Vanagon GL - "Wiesel"