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
>
>