Good points, but in this case the original poster has an 87 2wd with 2.1
and on these the thermo housing is plastic. It has a 2 wire sensor that
pushes into a smooth hole in the housing with an o-ring to seal it and a
clip to retain it.

On a 1.9 or a Syncro 2.1 there is a single wire sensor and these tips
apply more directly.

Mark

Daniel L. Katz wrote:
> list:
>
> would add to this that an alternate test is to run a jumper wire from a
> known good engine ground to the sensor housing, essentially the part you
> put your wrench on, which should be grounded where it screws into the
> thermostat housing, and see if gage reads properly. it is possible for the
> thermostat housing itself, via bolt corrosion i suppose, to lose its
> electrical bonding to ground. if there are several thousand ohms between
> thermostat housing and ground, then ditto for sensor housing, and gage
> will read cold irrespective of engine temperature.
>
> dan
>
> On Thu, 29 Nov 2007 09:53:55 -0700, Don Spence <dkspence@TELUS.NET> wrote:
>
>
>>Jumping in late here and uninformed as to what was said previously
>>but... with the ignition switch on, if you remove the wire that goes
>>to the sensor and ground it the gauge should  swing over to HOT.
>>Don't leave it there too long though. If the gauge doesn't move you
>>have a gauge or wiring problem.  If it does I would suspect the
>>sensor/sender.
>>On 29-Nov-07, at 6:18 AM, Automatic digest processor wrote:
>>
>>
>>>Subject: Re: Changed thermostat - temp gauge still reads stone cold
>>>
>
>