Kevo_6 Posted August 16, 2021 Report Share Posted August 16, 2021 On the way back from Malvern (which was very good) about half an hour from home, my temperature gauge started to drop to about 1/4 way past cold. My gauge is always in the centre when up to temperature and never really moves much, occasionally in traffic on a hot day it will rise. I’m assuming that the stat has stuck open. Is this a correct assumption? or is there any thing else I can check. I’ve not touched anything as of yet. Quote Link to post Share on other sites
HSM Posted August 16, 2021 Report Share Posted August 16, 2021 If the fuel gauge is also reading low, suspect voltage stabilizer on rear of speedo. Harvey Quote Link to post Share on other sites
HSM Posted August 16, 2021 Report Share Posted August 16, 2021 I forgot to mention that modern wax type t/stats fail in the closed position unlike the old bellows type that fail in the open position Harvey Quote Link to post Share on other sites
Kevo_6 Posted August 16, 2021 Author Report Share Posted August 16, 2021 Hi Harvey, thanks for your reply. My fuel gauge is reading good so doubt the voltage stabiliser. I will whip out the stat and check what I’ve got. Quote Link to post Share on other sites
PodOne Posted August 16, 2021 Report Share Posted August 16, 2021 Hi Kev Sounds more like a possible bad contact at the temperature sender unit or sender wire to the gauge. I'd suggest first cleaning the temp sender contact in the engine bay and check the wire where it connects to the spade for corrosion/oxidation before doing anything else and then perhaps change the sender if that fails to resolve the issue. Andy Quote Link to post Share on other sites
Mike C Posted August 16, 2021 Report Share Posted August 16, 2021 I changed the thermostat after a similar problem but it made no difference- in my case it was the voltage stabilizer or its wiring. Maybe try checking for a temperature difference between the water pump case and the top of the radiator during warm up with a remote sensing IR thermometer. Quote Link to post Share on other sites
Waldi Posted August 17, 2021 Report Share Posted August 17, 2021 Hi Kev, you can check the T-sensor with an Ohm-meter. The value (resistance) changes with temperature. My sensor failed too, and I first checked the new sensor, there are different types that can confuse you and can give wrong readings. Waldi Quote Link to post Share on other sites
Kevo_6 Posted August 18, 2021 Author Report Share Posted August 18, 2021 Thank you everybody, I now have plenty of things to check. Quote Link to post Share on other sites
astontr6 Posted August 19, 2021 Report Share Posted August 19, 2021 On 8/16/2021 at 5:12 PM, HSM said: If the fuel gauge is also reading low, suspect voltage stabilizer on rear of speedo. Harvey I would suspect the sender unit in the back of the thermostat housing or the wire Lucar terminal at the same place? The conductor can start break away leaving only a few strands connected ! This has happen to me in the past. Bruce. Quote Link to post Share on other sites
Alfrom Posted September 2, 2021 Report Share Posted September 2, 2021 sudden change to low reading temp gauge has happened to me twice now in 9 years. On both occasions caused by sensor going faulty, confirmed by resistance measurements taken against increasing water temp . In both cases resistance fell until about 75 degC was reached and then increased as temp continued to rise. Simple and inexpensive fix!! Gauge now reading dead centre with thermostat housing at 92degC, using an 82degC thermostat for reasonable heating in the winter. No mechanical fan just a rarely used manually-operated Kenlowe in front of the radiator, for the occasional need in certain traffic situations. Quote Link to post Share on other sites
Kevo_6 Posted October 18, 2021 Author Report Share Posted October 18, 2021 Just to bring this thread to a conclusion, it was the temperature sender that was at fault. Fortunately I had one in my spares. Sorry for the late response and many thanks to all that posted with your advice. Quote Link to post Share on other sites
TR6_PI_1969 Posted October 18, 2021 Report Share Posted October 18, 2021 Hi Kevo, Which one do you use now? Black one as in the attached picture or red one? The subject has been already treated on the forum... Thanks, William Quote Link to post Share on other sites
Kevo_6 Posted October 19, 2021 Author Report Share Posted October 19, 2021 Hi William It is a black one, not sure of it’s age though as I bought a job lot of spares about 10 years ago. The new one is a bit shorter than the old one. Temperature gauge now reading in the middle like the old use to do. Quote Link to post Share on other sites
roy53 Posted October 20, 2021 Report Share Posted October 20, 2021 where to purchase a good one ? Quote Link to post Share on other sites
Kevo_6 Posted October 20, 2021 Author Report Share Posted October 20, 2021 I don’t know Roy, but I would like to know also. Quote Link to post Share on other sites
John L Posted October 20, 2021 Report Share Posted October 20, 2021 I had a feeling that a while ago some were made with the wrong colour collars, so I suppose you need to take a resistance meter when buying. John Quote Link to post Share on other sites
TR6_PI_1969 Posted October 20, 2021 Report Share Posted October 20, 2021 12 hours ago, roy53 said: where to purchase a good one ? Hi, Maybe here, but it seems to be in the US... https://mossmotors.com/triumph-tr6-250/electrical-ignition/dashboard-gauges/gauges-switches-tr250-tr6-thru-1972 Quote Link to post Share on other sites
Waldi Posted October 21, 2021 Report Share Posted October 21, 2021 I bought mine from a local general car parts shop, once I knew the correct type (number). I checked the resistance before installing and it is fine. Waldi Quote Link to post Share on other sites
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