Modern shops have a newfangled heat sensor gun that is hand held and can give a
temp reading anywhere on the engine.

This device was first developed for the space program to be able to read the temps
at various points on the rockets. It's use was picked up by the auto racing
industry because it allowed the pit crew to take reading when the car was on the
track.

When aimed at the thermostat inlet and outlet lines it will definitely reflect the
opening and closing of the thermostat. You can read the temp change right off the
dial. As well as cylinder head temps. etc.

John Rodgers
"88GL Driver

Sharon & Miguel Calvin wrote:

> List gurus,
>
> These new-fangled water-cooled engines sure are different from my old 1600dp.
> Is there any way to check wether the thermostat is opening without removing it?
> I need to be certain that coolant is flowing through the rad so that I can
> be sure that my fan thermo-switch is bad.  See, if the thermostat is stuck
> closed, then the thermo-switch might never get hot enough to activate the
> fan.
>
> TIA
>
> Miguel Calvin                              ==+=========
> mcalvin@ican.net                          /[ ][  ][  ]}|
> Guelph, Ontario, Canada                  |  _       _  |
> "Frieden" is our 83.5 VW Campmobile      =='O`-----'O`-= ~~
> with 1.9l wasserleaker and manual trans.