Date: Sat, 1 Dec 2007 21:07:56 -0500
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: New thermostat funky?
In-Reply-To: <47519AEA.8090805@gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
So you are going crazy trying to get that last mile to the gallon and you
go ahead and install a thermostat that lowers engine temperature 10C. I
will display a bit of attitude here but there is no good reason or benefit
to doing this. In warm whether and high load, if the radiator can not keep
up with the heat load, the lower stat opening sooner only delays the
in-evitable. In addition, all aftermarket thermostats I have come across
just don't wok quite right. VW has done some work here and the OEM stat is
now on revision F. The major difference is the upper disc actually has a
rubber type seal on so that when it is closed there is virtually zero
passage of coolant to the radiator. The response is also much faster than
most t-stats.
The VW T-stat is actually used as a mixing valve. It is not a simple
open-closed set up.
Also, in extreme conditions, the cooling system should be able to handle
peaks up to 240F or more. Remember that 15 psi and 50-50 coolant mix
should be good up to 260F not the we want to go here. Low temp stats and
fan switches are either compromises for other issues or a false sense of
security. The real test is that coolant stays pressurized and flowing.
You also want to get the engine warm and have it stay fairly steady.
Having it constantly vary will add wear and each of these cycles helps get
those stud and gasket failures.
Yes, on extended down hill runs it is normal for the engine to cool off.
Especially if the front heater is going full blast. I always get a kick
out of folks opening all the levers and putting the front heater fan on
high to warm the interior up quickly. All that air is outside air! Yes
best heat is with that fan on a lower speed. In fact once under way I turn
the fan off and just let the ram air push in. Plenty of heat that way!
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Michael Elliott
Sent: Saturday, December 01, 2007 12:34 PM
To: vanagon@GERRY.VANAGON.COM
Subject: New thermostat funky?
A couple months ago I replaced the water pump -- it was making an ominous
grinding noise. Felt crappy when it was removed, too. Installed a new Temp
II sensor and thermostat at the same time. The thermostat came from one of
the usual online presences, can't recall exactly who but could find out if
it's relevant. The packing list noted that it was one that was set for 10
degree cooler than stock.
Indeed, with normal city driving at outside temps in the 70F range, the
temp gauge seems to rest just at the left edge of the LED whereas
previously it rode straight up, bisecting the lamp.
This morning I just returned from a two-night camping trip in the San
Diego mountains. It was 35F this morning and the first 2/3rds of the drive
are mostly downhill, a 6,000 ft elevation drop in about 60 miles. For most
of the downhill portion, the temp needle sat between the painted "box" at
the left-hand side of the meter face (this is a 1984 1.9L) and the left
edge of the LED, mostly closer to that painted box than the LED. In other
words, at about halfway between left (dead cold) and straight up.
The engine was so cool that the ECU went open-loop during long downhills
(auto transmission in "2," holding road speed down), as determined by the
Ken Lewis O2 monitor.
Once I got to the flats, in 55F temp, freeway speeds of 70 mph or so, the
needle rarely kissed the left edge of the LED.
This is new behavior, I'm not used to seeing the engine run that cool. I
know that a thermostat with a cooler set point may make it run cooler when
it's not being worked hard, but it should keep the engine warm. I can't
recall seeing the coolant that cold during downhills. That said, this was
the coldest weather I've made that run in. But still.
Next month I'll make the same trip, and it could be 20F cooler. I want to
be certain that the thermostat isn't, like, stuck open or anything.
--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR
