On our cross-country trip last spring, my 1.9L was reading too cool.
Sometimes the needle was barely going above the bottom line.  I assumed it
was the thermostat, but when we were slowing driving around campgrounds
looking for a site, the radiator fan would come on but the gauge was still
barely registering.  How could the fan be coming on if the coolant was
still below operating temperature?  Eventually I decided that there could
be a bad connection at the sending unit.  On the 1.9L it's a female push on
terminal to a pin with a flat head on it.  I cleaned the connector and pin
as best I could with a DeoxIT pen and carefully squeezed the connector with
a pair of pliers to give it a tighter fit.  The temperature gauge has read
right where it should since then.

On Mon, Dec 22, 2014 at 3:41 AM, SDF ( aka ;jim lahey' - Scott ) <
scottdaniel@turbovans.com> wrote:

> as stated some already ..
> a sudden loss of coolant can result in no change being noted on the temp
> gauge..
> since the sensor can't read steam or air very well.
>
>
> to the original poster ..
> AND..on a water cooled vanagon while driving you should look at the temp
> gauge about every minute..
> or every two minutes max.
>
> on a 2WD 2.1 waterboxer engine the t-stat housing is originally and
> usually plastic.
> there are two temp sensors..
> one is for Engine Coolant Temp to the ECU ..
> the other on runs the gauge .
>
> some things to watch out for ..
> the 4 hex head screws ( 10 mm wrench size ) about 20 times I've had the
> brass insert in the lower part of the housing spin in the plastic ..
> giving you a screw that won't come out ..
> making drilling or grinding the head off necessary.
>
> if it does come apart nicely ..
> put anti-seize on the threads of the screws going back in.
> fwiw ..unless I did it ..I have yet to see one drop of anti-seize on any
> threaded fastener on hundreds of vanagons I have worked on ..just
> something that people don't seem to know about or consider.
> it can make a huge difference next time it comes apart.
>
> where the temp sensors stick in the holes on the side of the t-stat
> housing ..
> if touching those ...nice to have new o-rings on hand.
>
> the big metal clips ..last time I got some at the VW dealer they are now
> plastic.
> Keep those good metal clips.
>
> the plastic where the metal clips go can break ...that plastic gets
> brittle with age.
> if you can ..
> replace the whole thing with a metal one.
>
> I like to run the warmer t-stat in the winter.
> I use only good german ones ..Behr brand .
> or Waller sometimes.
>
>
>
> On 12/21/2014 4:01 PM, Dennis Haynes wrote:
>
>> The 1.9L needs to have coolant actually flowing to read temperature also.
>> Even engines with the sensor in the head need the coolant to be accurate.
>> Same problem if the pump stops turning such as a belt failure. In both
>> cases the gauge will not read high until after you make steam or melt
>> stuff. Over the years I have removed a number of heads that have actually
>> melted along with some piston tops.
>>
>> Dennis
>>
>>
>> -----Original Message-----
>> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
>> Of mark drillock
>> Sent: Sunday, December 21, 2014 8:05 PM
>> To: vanagon@GERRY.VANAGON.COM
>> Subject: Re: 87 Westy overheating after coolant change
>>
>> That is an excellent point. The 86+ has the temp gauge sender in the
>> thermostat housing. It needs coolant flowing to get an accurate reading,
>> especially with the plastic housing most vans have. Syncros have a metal
>> one and there are metal aftermarket ones available as well.
>>
>> Mark
>>
>> Kevin Duvernay wrote:
>>
>>> Thanks. I will add a new thermostat to the to-do list. Quick question,
>>> where is the sensor for the temperature gauge? Is it measuring coolant
>>> temp or engine temp? Im trying to think about what its response would
>>> be if there was a catastrophic loss of coolant, a major leak.
>>>
>>> Kevin
>>>
>>>
>>>
>>