Coolant Temp Gauge - Actual Temperatures

[sport1901966 8]

Thought my recent test may be of interest to others!

 

We all know the reputation of the dash gauges and since rebuilding the engine I decided it would be worth finding out exactly what temperature the coolant temp gauge bars indicate.

 

I used some 50:50 antifreeze, a digital thermometer and a camping stove. I took out the gauge sensor and hung it into the antifreeze right next to the digital thermometer sensor. I used the vehicle wiring and some temporary extension wires (earthing on the thermostat housing as would be the case when mounted). I heated the antifreeze up to about 130^oC and noted the position of the gauge and associated temperature throughout.

 

Anyway here is the set up:

 

 

And the results:

 

 

Surprisingly accurate really considering the reputation. The first thin bar is 60^oC then a 20^oC jump to 80^oC at the following thick bar then up in 10^oC jumps from there on. This was done on a G reg 1.9, although I assume these would be standard across the range.

 

Anyway hope this is of use to people!

[Tesstuff 222]

Excellent post mate, I like to see something different

[Anthony 1,003]

Interesting to compare your results with what they are in theory supposed to be...

 

 

What would be interesting is to compare several sets of gauges and senders, and see how widely they differ, as my suspicions is that there will be a fair variation. I know that my own 205 for example seems subjectively to more closely resemble the clocks above, judging by the thermostat temperature (82 degree), rad fan switching temperature (92 degree) and overheat warning light switching temperature (110 degree).

 

Good test though

[sport1901966 8]

Excellent post mate, I like to see something different

 

Thanks!

 

Interesting to compare your results with what they are in theory supposed to be...

 

Image

 

What would be interesting is to compare several sets of gauges and senders, and see how widely they differ, as my suspicions is that there will be a fair variation. I know that my own 205 for example seems subjectively to more closely resemble the clocks above, judging by the thermostat temperature (82 degree), rad fan switching temperature (92 degree) and overheat warning light switching temperature (110 degree).

 

Good test though

 

 

Thats a great image to compare with, it would appear my results are about 10^o higher at any given position. I suspect your right with regards to the variation though. I did the test a couple of times and at least the gauge positions are repeatable. I think I have another couple of senders lying around, if i get (very) bored maybe I'll test those as well. Although this still wouldn't account for potential variation in the gauges themselves. I guess we know why they didn't bother printing numbers on them!

[Henry Yorke 269 3 Cars]

Great test. The fan is two speed though so I think one comes in at about 86 degrees. Having lost the factory fan on mine, I just run a single speed and that kicks in at about vertical. I also run an 82 degree stat too. IIRC there are some variations in the rating of this as some are higher. I think the stats have the temperature stamped onto them.

 

I once did a similar test with a stat in a pan of boiling water on the hob!

[Anthony 1,003]

There's numerous different thermoswitches Henry which all have fairly significant differences in switching temperature, as well as some that were single speed and some which were dual speed - I did do a post listing them all once upon a time. A trawl of various 80's and 90's PSA models in the scrappy tends to reveal three common later style thermoswitches, identified by the purple, red, and yellow bandings on them to indicate the different temperatures.

 

There's two common different 'stats available - 82/83 degree and 89 degree, 205 GTi's having the later as standard from what I can tell. There are other 'stats available - I'm not sure exactly what car/model it's originally from, but Skip Brown supply/fit a 72 degree 'stat to their engines for example.