ScottR400D Posted May 25, 2016 Share Posted May 25, 2016 just a quick question! The water temperature sensor in my car is a brass 1/8NPT threaded VDO one, 0-150 DegC. The spec of this sensor says it suits VDO gauges of the same temperature range. The gauge in my car reads from 40 to 120 DegCI guess this may be a dumb question but does it matter? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 25, 2016 Member Share Posted May 25, 2016 Not dumb: it might.Can you find the part number on both?Jonathan Link to comment Share on other sites More sharing options...
ScottR400D Posted May 25, 2016 Author Share Posted May 25, 2016 Not on the gauge. On the sensor it has various markings on the hexagon flats:150C; TC600; 0000901; 6-24; 4DFrom what I can see looking on line, it's not an OE VDO sensor (hey are normally clearly marked VDO) but it is what Caterham supplied with my kit last year. It seems to work OK, in that the car runs between 75/80C or so on the gauge, (normally at 80 but drops momentarily when you wind the speed up, returning to 80 when 'cruising'). I believe I has an 82C stat. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 25, 2016 Member Share Posted May 25, 2016 Hmmm... I'm trying to think of the best approach: Wait and see if anyone who knows the answer comes along... Try and work it out from manufacturers' data sheets... Measure the resistance of the sensor against known temperatures then put those resistances across the gauge... Heat some water to 90° and put the sensor in it and see what the gauge says...JonathanPS: That running temperature below the thermostat value isn't explained yet, but it's not uncommon. I'd ignore it until we know the gauge is about right. Link to comment Share on other sites More sharing options...
ScottR400D Posted May 25, 2016 Author Share Posted May 25, 2016 Thanks JK. I don't think it's far off, when the gauge shows 80, a pyrometer aimed at the sensor body indicates about the same. But the idea of putting the sensor in water of a known temp makes sense. I can rig that up quite easily I think because I have a couple of spares. The car came with two similar sensors one of which goes into a tapping in the oil tank, just to plug the hole. I've put a switch in and wired both sensors in so I can flick between water and oil temps, and it dawned on me that the sensor range doesn't match the gauge range, though I don't know that it needs to Link to comment Share on other sites More sharing options...
ScottR400D Posted May 26, 2016 Author Share Posted May 26, 2016 Well, I've just returned from a run to try out my dual temperature sensing set up. I put two new sensors in, which had better, IMO, connections, being a threaded post and nut, rather than the 'button' tops that CC supplied.The water with the new sensors is running at the same temperature, as you'd expect, but is less sensitive in that is slower to move between 80/75 than it was. I would have thought the sensitivity was more in the gauge but it appears not.The switch works which has enabled me to measure the oil temperature at the bottom of the oil tank, before the oil goes back into the engine. It reads about 70C, which is OK I think, after cooling and when not being worked too hard, though I'd appreciate any opinions on that. Link to comment Share on other sites More sharing options...
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