[Vwdiesel] [Diesel Volkswagen Club] 1981 Rabbit water temp sensor

[Val Christian]

Yes, I've seen it happen.  Sensors can be bought readily.  
Try any of the outfits selling VW parts over the internet.
Email me, and I will give you my primarily source, but there 
are several which provide reasonable prices and great service.
I'm just guessing, that you will pay 12-20 bucks for a sensor.
Chances are the sensor you buy will not be made in China.

You really don't need anything more accurate, just get the system fixed.
Probably the sensor.  If your gas gauge is reading wrong, then
it might be the voltage regulator in the instrument cluster.
One of the list contributors has posted detailed instructions
on replacing the voltage regulator.  (I did one before he posted
his instructions, so I have not used them.)

Owning a passive radiometer (so called laser temperature gauges) is
a GREAT diagnostic tool.  Keep in mind they are radiometers, and
relay in radiated energy to give you a temperature.  For a spot 
read, use them up close. 

They are affected by the emissivity of a surface, and the best
surface to use with most, is a painted surface.  I spray 
painted flat clack rectangles on a cyl head and radiator of a
vehicle I was having problems with.  That way I got consistent
and more accurate readings.  Shiny surfaces can have quite different
emmissivities than painted or dull surfaces.  Most PIR gauges
are set for a .95 emmissivity, which is close to most paints and
skin.

Start with the sensor.  After 25+ years they can fail.

Val


> 
> About a year ago, the neck on my plastic radiator broke off, and the 
> motor over-heated.  Afterwards, it repeated over-heated all the 
> time.  After exhausting (no pun intended) all the other 
> possibilities, I gave up and admitted it had a blown head gasket.  
> When I took it into the local specialists, they convinced me I'd be 
> better off having them rebuild the motor.  After getting it back, it 
> appeared to be running hot (and yes, after driving it with a blown 
> head gasket for almost a year, I was spooked).  I took it back 
> yesterday, and after checking everything out with an infared sensor, 
> determined that the gauge was reading more than a little high.  I've 
> never had either a water temp sensor or gauge go bad in any 
> vehicle.  I'm thinking that the odds are it is the sensor and not 
> the gauge, and that maybe the repeated over-heating "cooked" the 
> temp sensor.   Anyone else seen this happening?
> 
> I was just going to put in an accurate digital temp sensor gauge in 
> addition to the existing gauge, but I'd still probably keep watching 
> the wrong gauge out of habit.  I've had some pretty poor luck with 
> Chinese "Rabbit replacement" parts, can I still get a replacement 
> temp sensor from a good source?