Dave pb Posted October 11, 2019 Report Share Posted October 11, 2019 Hello The temp gauge has always read at the same place between Cold and Normal for the last 15 years, except once when it really overheated in a queue on the M6 and went up to Hot, so it definitely works. It would be nice if it read Normal when it is normal. Likely fix? New thermostat? New sensor? Any suggestions? Cheers Dave === Link to comment Share on other sites More sharing options...
Nigel Clark Posted October 11, 2019 Report Share Posted October 11, 2019 Normal on my 1972 GT6 has always been about 40% of full gauge deflection, ie slightly below midway. Anything more and the engine is getting too hot in traffic etc but comes back to the usual reading when in the move. Could your thermostat be faulty? Nigel Link to comment Share on other sites More sharing options...
Dave pb Posted October 11, 2019 Author Report Share Posted October 11, 2019 Hi Nigel It could be faulty, and I could try another. Your gauge seems to have the same "normal" as mine by the sound of it. Perhaps that is "Normal"? Dave Link to comment Share on other sites More sharing options...
Clive Posted October 12, 2019 Report Share Posted October 12, 2019 Several checks can be done. What is the actual temperature? Simple way is to buy a digital thermostat off ebay for a couple of £, loosen a hoe clamp and poke the sensor into the join far enough it is in water. Test the thermostat in boiling water for accuracy first (mine read 99degrees, which is plenty accurate enough) If all is well, and the water reads approx thermostat temp when running, it could be: voltage regulator (is the fuel gauge accurate or does that read low too? both fed from the 10v regulator on the back of the speedo) the sender unit. Care needed, some sold look correct but are for Landrovers and over read.... Gauge under reading. Years ago a friend had an overheating issue. In fact it wasn't, it was spot on, but the gauge ran at 3/4 as normal. At the time I had some spare used sensors and gauges. I swapped them around until I got a combo where it sat in the middle. He was very happy that the overheating had been fixed.....not sure he really grasped what I had done. Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 12, 2019 Report Share Posted October 12, 2019 In after market there are 3 thermostats a 78c 82c and 88c The general std for these cars in uk is 82c if fitted with a78c it will read lower than mid way If a 88c then higher than mid way Stats that have been boiled /overheated are best dumped as they can get de calibrated by cooking Even a cheapmstick thermometer from the local chemist stuck in the filler will give you some sound clues Most voltage stabilisers tend to over volt and give high readings when the 10.5 v becomes 12v stabilised gauge Senders are GTR108 if its fitted with a non stab sender 121997 you get really odd readings These used to be colour coded green or red but many are now all cheap black Pete Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 12, 2019 Report Share Posted October 12, 2019 17 hours ago, Dave pb said: Hello The temp gauge has always read at the same place between Cold and Normal for the last 15 years, except once when it really overheated in a queue on the M6 and went up to Hot, so it definitely works. About 1/3 of the way along, certainly just under halfway, seems to be the usual point. If the car isn't overheating or running even slightly too hot, just accept this as the usual position, and then you'll easily recognise any movement in either direction. If mine approaches the 6 o'clock position I'm starting to get paranoid. Link to comment Share on other sites More sharing options...
dougbgt6 Posted October 12, 2019 Report Share Posted October 12, 2019 My gauge used to sit at halfway, but having flushed the block, moved the number plate from obstructing the grill, And replaced the sagging radiator cowl it now sits at a third. Gauges can be inaccurate, the important thing is “is it reading different from yesterday?” Doug Link to comment Share on other sites More sharing options...
Dave pb Posted October 13, 2019 Author Report Share Posted October 13, 2019 All makes sense. from an aesthetic point of view I would like it to point to midway, I think I will try a different thermostat and see what happens . thanks Dave ==== Link to comment Share on other sites More sharing options...
JohnD Posted October 13, 2019 Report Share Posted October 13, 2019 Dave, The sensor/gauge system on Triumphs, and many other cars, is dead simple. The sensor is designed to fall in resistance as the temp rises. This is contrary to the usual way that all other conductors work, and is a bit iffy! But as the temp rises, more current flows through the gauge and it also rises. That's it. But you can calibrate it. Take out the sensor, and arrange it on a long lead in pan of water that you can heat. In the garage, a camp stove is ideal. With the ignition on, heat the water while observing the temperature on the guage. Measure the water temp. in the pan at, say, a quarter, halfway, threequarters of the temp scale, and at "HOT". Now you know exactly where you are! If you want to diddle with the position of the needle, then you need to change the resistance of the sensor, or at least what the guage 'sees'. Try a few different sensors - they vary a bit. You may find one that puts your need where you want it. John Link to comment Share on other sites More sharing options...
dougbgt6 Posted October 13, 2019 Report Share Posted October 13, 2019 Guy across the road got a camping stove in the garage for this very purpose. His wife thought it a great idea, had him cooking all the fried food in the garage to save making the kitchen smelly. Pretty soon he was cooking ALL his food in the garage. Then there was the garage shower unit...... You have been warned. db 1 Link to comment Share on other sites More sharing options...
Adrian Cooper Posted October 13, 2019 Report Share Posted October 13, 2019 I had the same problem with the temperature gauge reading too high on my Spitfire even though a check with a thermometer confirmed the engine was not overheating. I tried several different senders and none of them put the needle in the middle. So I took Pete's advice on a previous thread and adjusted the gauge to read 'normal' in the car's usual operating temperature. I've had a quick search for the thread but couldn't find it, but the adjustment of the gauge is fairly simple, if a bit 'hit and miss'. If you take the gauge out of the car and look on the back you will see two small holes filled in with small rubber or cork bungs. These give access to the adjustment within the gauge which should be done with the correct tool, but a small screwdriver can work. Small movements at a time are the trick. I ran the car for the next few days with a cheap ebay digital thermometer, with its probe attached to a water hose, just to check that the gauge was going to indicate if the engine did get hot and I was happy to see that it did go above normal when stopped in traffic. It was a bit of a faf but I now have a gauge that sits in the middle and one that I can have some confidence in. I'm sure that Pete will be along soon if I have got any of this wrong. The picture attached shows one of the adjustment points and the other is in the plate marked 'coil' Adrian 1 Link to comment Share on other sites More sharing options...
JohnD Posted October 13, 2019 Report Share Posted October 13, 2019 Gosh, Adrian, I never knew that! You have educated me! You made me research it further, so may I post this link, becasue I think it augments your valuable post! "TonyFixit" in Canada, shows some more details and pictures on how to calibrate your gauge: https://www.triumphexp.com/forum/odds-and-ends-forum.9/calibration-of-smiths-temperature-and-fuel.1405143/ John 1 Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 13, 2019 Report Share Posted October 13, 2019 I'm going to risk sticking my neck out here (It's not like me!!) and ask: can't you just bend the needle? Gauge internals are reading the same but needle now sits in the preferred bit of the face? Link to comment Share on other sites More sharing options...
Adrian Cooper Posted October 13, 2019 Report Share Posted October 13, 2019 Good detective work John, that's where I discovered this stuff. And that answers why I couldn't find the thread on this forum too! That's an interesting point Colin, In theory just bending the needle would reduce the available range of movement in the gauge, whereas using the adjustment points will shift the centre point of the whole gauge; In practice I doubt it makes much difference in such a crude instrument. Adrian Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 14, 2019 Report Share Posted October 14, 2019 the two dots on the face are the calibration marks for a set voltage as used by the smiths test box or the maker. for testing senders and gauges we had a hot tank with a temperature control and circulation which was controlled to within better than 0.1C be it senders or stats youre not boiling an egg that may give you an idea but its more techy than that pete Link to comment Share on other sites More sharing options...
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