The temp gauge responds to the coolant that should be flowing through the
engine. The radiator fan is turned on by a switch in the radiator itself.
Having the engine overheat without the radiator getting hot enough to turn
on the fan is the symptoms of a bad thermostat or when intermittent
combustion gasses getting into the cooling system.  These gases and/or a bad
pressure cap can cause coolant to blow out while driving and then be low for
the next cold start turning on the low coolant light until the coolant warms
and expands.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Mike Miller
Sent: Sunday, January 08, 2012 6:11 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: temp gauge shenanagins

Sorry for the late replies, I've been out and about.

The needle has done this before, swept over to high but no high speed fan
on, then later fall back to normal with nothing changing.

Now red light blinks all the time but the needle is behaving, for the time
being at least.

Mike

On Jan 8, 2012, at 9:32 AM, David Beierl wrote:

> At 12:02 AM 1/8/2012, Mike Miller wrote:
>> But...my temp gauge goes sl[e]wing up to the red zone and the light
>> blinks.
>
> Less common reason: short to ground in the temp sender wiring.
>
> More common reason:  you have an old-style coolant-level controller as
> found in roughly pre-'85 vans, and it has triggered.  Could be a bad
> controller (and anyway you'd rather have the newer, cube-shaped one
> which will cause the light to blink without visibly affecting the
> needle), but more likely it's an open in the wiring of the level
> sender (the plug comes to mind) or the sender itself which is just two
> s/s pins sticking down into the pressure bottle.  Scrub the pins with
> ScotchBrite, check/clean the connector, make sure the ground is good.
> If you're running a very weak coolant mix that could conceivably cause
> this as well.
>
> Sight unseen my bet is on the connector at the pressure bottle.
>
> Yrs,
> d