Crawfie Posted July 30, 2014 Report Share Posted July 30, 2014 A little update on SVN850K...... Carb heat shields fitted. Mechanical fan reinstated. Thanks Conrad. Evans coolant ...removed and anti freeze and water back in. Thermostat replaced and temp sensor replaced. Running great. Expansion bottle 1/2 full. No leaks. SO why is the bloody temp gauge needle go straight to the red ???? It stayed there the whole time I drove the car. I ignored the gauge and enjoyed the ride tonight and saw a nice red TR4 on the moors tonight. What's gone wrong this time ?? Steve Quote Link to post Share on other sites
carld Posted July 30, 2014 Report Share Posted July 30, 2014 What was the fuel gauge reading Steve? Quote Link to post Share on other sites
Crawfie Posted July 30, 2014 Author Report Share Posted July 30, 2014 Hi Carld, The fuel gauge reading was in the middle. Are you thinking that the voltage stabilizer is buggered ?? When the Evans was in, the temp gauge never did this. Never went straight to the red and stayed there like now. I have a kenlowe and a original fan . Steve Quote Link to post Share on other sites
PJM Posted July 30, 2014 Report Share Posted July 30, 2014 Temperature sender or duff connection or lead Quote Link to post Share on other sites
Crawfie Posted July 30, 2014 Author Report Share Posted July 30, 2014 Hi PJM, New sender fitted today. Black tipped one from Rimmers. Are they any good or us there a better supplier ?? I'll have a look at the cable and connections tomorrow. Steve Quote Link to post Share on other sites
Fireman049 Posted July 30, 2014 Report Share Posted July 30, 2014 Have you an airlock in the cooling system? Tom. Quote Link to post Share on other sites
TR NIALL Posted July 30, 2014 Report Share Posted July 30, 2014 Have you got the Stat the right way up??? Quote Link to post Share on other sites
Don H. Posted July 30, 2014 Report Share Posted July 30, 2014 Always look for confirmation of data that alarms you. Maybe a cheap IR thermometer pointed at the black metal near the thermostat housing? On my TR3B this confirmed that the temperature was indeed higher than target, confirming the capillary gauge and the puked coolant on the garage floor. With no other symptoms of hot running on your car the data has to be double-checked. On my car a combination of factors returned the car to perfectly normal. These included replacing the modern Wizard Cooling aluminum radiator with a re-cored original, replacing the puny four-bladed fan with a high-pitch, six-bladed tropical fan, and replacing the carburetors after the original rebuilder re-bored the shafts crooked leading to binding. The remaining thing we didn't need to get to on my car was confirming performance of the water pump. Good luck -- watching a temperature gauge is no way to enjoy a TR. I know this firsthand. Quote Link to post Share on other sites
Dave Smith Posted July 31, 2014 Report Share Posted July 31, 2014 Steve Two things you may wish to consider I would revert back to your original temp sensor, and see is that consistent with before your changes. Test your thermostat or remove it for a whilst. Quote Link to post Share on other sites
hot-growler Posted July 31, 2014 Report Share Posted July 31, 2014 definitely electrical issue, wire is earthing somewhere along it's run. straight to red has nothing to do with temp of coolant. either replace wire, or fit alternative temp device. Quote Link to post Share on other sites
carld Posted July 31, 2014 Report Share Posted July 31, 2014 I was potentially Steve or earth, however the lads have all comeback with the usual likely issues, I take it that the kenlowe wasn't kicking in and that you don't actually have an overheating problem. Cheers Carl Quote Link to post Share on other sites
trt74 Posted July 31, 2014 Report Share Posted July 31, 2014 Have had just the same problem and it appeared to be the voltage stabiliser after all! Because of the fact that your temp gauge needle goes straight into the red after starting, I would put my money on the voltage stabiliser. Cheers, Tim Quote Link to post Share on other sites
Steves_TR6 Posted July 31, 2014 Report Share Posted July 31, 2014 (edited) you can easily check the voltage 'stabiliser' by measuring its output voltage, should be 10Volts or swap for a know good one from a local TR pal, or i have one if no-one else does. you can also measure the resistance of the sensor side connection to the gauge, but i dont know the correct resistance, it should not be 0 ! again try swapping for a know good one. IF the needle goes to the red without the engine even running then that's an earthing problem, ie the sensor wire is shorting to earth. hth steve Edited July 31, 2014 by SDerbyshire Quote Link to post Share on other sites
peejay4A Posted July 31, 2014 Report Share Posted July 31, 2014 You haven't swapped the ignition coil and the temp sender leads over by any chance? Quote Link to post Share on other sites
Crawfie Posted July 31, 2014 Author Report Share Posted July 31, 2014 Thanks for the advice gents !! Thermostat is in the correct position. Correct wire connected. The temp needle , after starting up, went as a gradual sweep to the red and stayed there. Very little movement from the red. I've done something when I fitted the new parts and got rid if the evans coolant. I will check everything suggested tomorrow. I suspect the cable is dodgy , but i will work through all the advice given. I have got a new voltage stabilizer ready to go in. The car ran really well yesterday. The best for ages . Very unsettling seeing temp gauge not behaving . Fingers crossed ! Update tomorrow . Steve Quote Link to post Share on other sites
peejay4A Posted July 31, 2014 Report Share Posted July 31, 2014 What's the voltage at the temp sender contact? Quote Link to post Share on other sites
john.r.davies Posted August 1, 2014 Report Share Posted August 1, 2014 To say that voltage stabilser volts should be "10V" is misleading, unless you have a modern diode stabliser. The OE version is a magnificent bit of Victorian engineering, a bi-metallic strip that bends as it is heated by the current, breaking the circuit so that it cools down again, bending back and remaking the contact. Current flows, it heats up again and so on. What you see with a multimeter is 12V (or whatever the system is delivering right then) - Nought Volts - 12V, alternating. If you don't expect this, it looks like a faulty stabiliser, but that's the way it works! The guages are heavily damped, so they average this intermittent voltage to 10V. And "straight to red" is a way of checking the guage, by earthing the wire at the sensor, for both temp and fuel gauges. Instaed of the variable resistance in the sensor, NO resistance causes the gauge to head for HOT/FULL and stay there. NIot a good thing to leave it there, so check the wire between guage and sensor for a short, asap. Meanwhile disconnect from gauge, else the wire and guage may overheat. John Quote Link to post Share on other sites
ken foster Posted August 1, 2014 Report Share Posted August 1, 2014 A little update on SVN850K...... Carb heat shields fitted. Mechanical fan reinstated. Thanks Conrad. Evans coolant ...removed and anti freeze and water back in. Thermostat replaced and temp sensor replaced. Running great. Expansion bottle 1/2 full. No leaks. SO why is the bloody temp gauge needle go straight to the red ???? It stayed there the whole time I drove the car. I ignored the gauge and enjoyed the ride tonight and saw a nice red TR4 on the moors tonight. What's gone wrong this time ?? Steve Which thermostat did you replace? I had a problem with boiling with a new stat. (TR6) I drilled a hole in the new one and fitted the poppet valve from the old original. That allows the air to escape upwards. Worth doing if you have a poppet valve. I just drilled a hole in another classic I own, (the thermostat, not the car) and it helped stabilise the cooling. (V6 Essex engine) Good luck Quote Link to post Share on other sites
DIYBOSSCAT Posted August 1, 2014 Report Share Posted August 1, 2014 Steve, another thing you can try is to run a separate wire from the sender straight to the gauge, if it still goes to red then its prob a voltage stabiliser fault. Cheers, Vince. Quote Link to post Share on other sites
Crawfie Posted August 2, 2014 Author Report Share Posted August 2, 2014 OK.... Today I changed the temp sender. Same result. Run a new cable from gauge to sender. Same result. In the process of fitting the new cable, gauge fell to bits.!! New problem. So I need a new temp gauge. Went out for a run, noticed fuel gauge went from 3/4 to 1/4. Will be taking out the speedo tomorrow and replacing the voltage stabilizer. There is a real horror story behind the wooden dash. I have never seen so many wires that connect to nothing. Bulb holders with no bulbs in etc. Winter project will be a dash refurb. Thanks to all for the advice and tips. Steve Quote Link to post Share on other sites
simpson Posted August 2, 2014 Report Share Posted August 2, 2014 OK.... Today I changed the temp sender. Same result. Run a new cable from gauge to sender. Same result. In the process of fitting the new cable, gauge fell to bits.!! New problem. So I need a new temp gauge. Went out for a run, noticed fuel gauge went from 3/4 to 1/4. Will be taking out the speedo tomorrow and replacing the voltage stabilizer. There is a real horror story behind the wooden dash. I have never seen so many wires that connect to nothing. Bulb holders with no bulbs in etc. Winter project will be a dash refurb. Thanks to all for the advice and tips. Steve Yeah, one needs to be really careful with the behind the dash wiring connections and all the misc. gauge post fittings. If any are inverted/upside down or too close or touching the gauge mounts etc, bad electrical spooks show up. Quote Link to post Share on other sites
Marc R Posted August 2, 2014 Report Share Posted August 2, 2014 (edited) @ Crawfie, Is your issue new or you faced this issue since a long time? On my Stag I faced since the beginning a same issue, temperature gauge moving quickly (usual warm up sequence) near to the red zone but then very stable , Voltage stabilizer was Ok, the Fuel gauge was Ok, the thermostat was working as expected .... and the car was working very well! I bought a IR thermometer and discovered that the issue is the calibration of the Temp. Gauge, Instead of changing the sender, I solve the issue with a ohmic resistance in serial to reduce the amp (cost nearly nothing). After few tests, I find the right ohmic value to have the needle near the middle of the scale ! Kind regards Edited August 3, 2014 by Marc R Quote Link to post Share on other sites
john.r.davies Posted August 3, 2014 Report Share Posted August 3, 2014 Steve, Rather obviously, but not previoulsy mentioned, the probelam is not the water syetem but the "real horror story behind the wooden dash". Good luck with that, and forget the fictitious overheating for now. Spend money on an infrared thermometer, a useful tool that will vastly reassure you. JOhn Quote Link to post Share on other sites
stuart Posted August 3, 2014 Report Share Posted August 3, 2014 Better still spend money on a new loom by the sound of it. Stuart. Quote Link to post Share on other sites
Steves_TR6 Posted August 3, 2014 Report Share Posted August 3, 2014 (edited) One of the first jobs I did on my present tr6 was to strip out all the unnecessary additional wiring fitted by various POs. I was astonished how much there was! This made the winter dash refurb much simpler as there were only the original wires left! Steve, I have a good used voltage reg and spare inwards for the temp/fuel gauge, and spare veneer, if you need them. Steve Edited August 3, 2014 by SDerbyshire Quote Link to post Share on other sites
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