How do I...

[Shnozz]

get a thermostat temperature reading so as to see whether the gauge reading is accurate. I am 99% certain the gauge reading is 20 degrees over what the actual temperature is. A lack of overheating and the fans switching on ok but at 120 suggest thats the case! I think I may need to either try a new temp sender or add some resistors to the set up to make the gauge reflect the true temp but I want to get a thermostat reading so I can be certain the gauge is 20 degrees over.

Any ideas? many thanks

[Le TVR]

A non-contact (IR) thermometer should work.
Some garages use them for diagnostic work. You just point it at the part you want to measure.

[s3swiss]

How about sticking one of these on the thermostat housing or whichever metal pipe you require?
www.frost.co.uk/item_Detail.asp?productID=8691

[mickypee]

I fitted an adjustable temp gauge sender to my Griff, but it will fit the S. The product is from Modwise, and it fits on top of the sender, and plugs into the loom. Simply adjust until the gauge reads correctly. Only costs a few pounds, well worth it.

[profstoff]

You could take the sender out and stick it in a pot of hot water with a reliable thermometer. Then compare the reading on the temp gauge with the thermometer. The surface measuring devices mentioned earlier in the thread would give an indication but you would have to factor in the fact that they are only reading an external surface temperature, not the temperature of the water.

[honourablepickle]

IR thermometers are a bit hit and miss unless you have a posh one
I've found plumbers thermometers the best and spot on readings for £20
reb

[Pies]

You could set the gauge to your fans.I.E you know what temp your otter switch cuts in at so you could just wait until the fans cut in,job done.It does not need to be superbly accurate as its only a gauge.

Get the modwise adjuster as previously mentioned

[Shnozz]

thats the thing you see - how do I know the otter switch is correct? Shirley thats as unreliable as the temp sender? The fans are cutting in ok and the car isnt overheating when the gauge is reading 120. The fan cuts in them but the gauge hasnt got any more room to go up further!

I guess by setting the gauge to the fans using resistors would be a start

Thanks for the other ideas chaps. Will try contacting David Beer at Modwise but his time in the far east usually means weeks if not months before you get a response.

[Pies]

If you want to borrow an IR thermometer, i have one

[Shnozz]

cheers Pies. How accurate are they? Geography may dictate that I decline your kind offer though mate, but I may be able to source one locally

[Pies]

plus minus two degrees

P.S the post system seems to work

[Shnozz]

I'll mail you Sir

[JONZO]

Schnozz, i had exactly the same problems as you describe, so booked the S into a car electricians to check out all the wiring etc to the fan & otter switch. He tested the temp throughout the day comparing the S gauge to his thermom. He confirmed the gauge was reading 10-15 degrees over at all times, so the fan had been kicking in when it should, thankfully, not when it was in the red as the guage indicated. He also confirmed the wiring in an S is a mess and several items were overloaded !! He said he'd done the same procedure on a few S's so it must be another case of 'they all do that sir'?