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Post by halkyon on Jul 26, 2022 18:16:14 GMT
Just went for a shake-down drive as I plan to attend a rally on Saturday. All went well until I lost all auxilliary electronics - stopped and replaced the fuse even though it looked fine to no improvement, then wiggled the connection blocks on the firewall and it seemed to come back to life - perhaps the connections on the back face of the fuse block.
Also - my temperature gauge is scaring me. I have an aftermarket temperature sensor in the top hose to turn the fan on at 85c now and the gauge is kissing the white 'H' line by then! 10v voltage stabiliser?
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Post by dave1800 on Jul 27, 2022 0:38:03 GMT
Unless your aftermarket sensor is identical to the original the gauge will not read correctly. You could disconnect the sensor when the engine is hot and the reading is as shown in your pic and without delay measure its resistance. Then take it out and place it in water heated to 85C to compare the resistance which should fall as the temperature increases. Someone here may have a calibration chart for the original part or it's worth a Google search.
David
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Post by halkyon on Jul 27, 2022 8:02:12 GMT
Sorry I should have been more clear - the aftermarket sensor only triggers the fan relay and the original sensor (as far as I know) is wired to the temperature gauge.
Looking behind the gauges it has been messed with at some point, with a modern plastic splicer in there doing something.
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Post by foglaursen on Jul 27, 2022 8:54:04 GMT
Just yesterday I tested 4 different used temperature sensors and one new sensor. They all gave significantly different readings. Peter
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Post by dave1800 on Jul 27, 2022 9:41:19 GMT
Hi Peter That's interesting. The sensor output is not linear. For example the details I have found show the following resistance values: 0 C 5896 ohms current through gauge at 10V = 1.6ma 40C 1179 ohms current through gauge at 10V = 8.5ma 80C 323 ohms current through gauge at 10V = 31 ma 100C 185 ohms current through gauge at 10V = 54 ma It would be interesting to see whether there was a significant variation at the higher temperatures. David Just yesterday I tested 4 different used temperature sensors and one new sensor. They all gave significantly different readings. Peter
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Post by dave1800 on Jul 27, 2022 9:45:47 GMT
Definitely something worth sorting out and checking whether the gauge is reading high or if the engine really is running on the hot side. Is the sensor that triggers the fan relay adjustable? If so it may be worth getting it to turn on a little earlier to be on the safe side. David Sorry I should have been more clear - the aftermarket sensor only triggers the fan relay and the original sensor (as far as I know) is wired to the temperature gauge. Looking behind the gauges it has been messed with at some point, with a modern plastic splicer in there doing something.
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Post by foglaursen on Jul 27, 2022 10:27:40 GMT
I tested the sensors at temperatures around 80C with a 52mm Smiths instrument. The readings were as follows: Sensor 1, new: 35C above actual temperature Sensor 2: 16C above Sensor 3: Exact Sensor 4: 7C above Sensor 5: 45C below The sensors could be intended for other instruments than mine, which might explain the difference. The used sensors are mostly from 1800 Landcrabs.
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Post by halkyon on Jul 27, 2022 10:43:13 GMT
Is the sensor that triggers the fan relay adjustable? If so it may be worth getting it to turn on a little earlier to be on the safe side. It isn't, so I've wired up an manual switch to activate the relay too. Turning that on does lower the temperature - but for all I know that could be a voltage drop across the gauge circuit!
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Post by dave1800 on Jul 27, 2022 12:59:56 GMT
Thanks Peter. This shows the importance of matching gauge readings to reliable temperature measurements before trying to diagnose apparent hot or cold running. I wonder how many of us have done this (I hang my head in shame!) David I tested the sensors at temperatures around 80C with a 52mm Smiths instrument. The readings were as follows: Sensor 1, new: 35C above actual temperature Sensor 2: 16C above Sensor 3: Exact Sensor 4: 7C above Sensor 5: 45C below The sensors could be intended for other instruments than mine, which might explain the difference. The used sensors are mostly from 1800 Landcrabs.
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Post by halkyon on Jul 27, 2022 14:07:22 GMT
Would a second temperature sensor fit in the top of the radiator where my old inoperative sensor for the fan is? Or perhaps there is a blanked off area somewhere on the cylinder head?
The security of a well calibrated gauge with degrees might be welcome.
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Post by Penguin45 on Jul 27, 2022 17:30:16 GMT
Thermal Senders by Penguin 45, on Flickr Temperature senders - item 9. BMK1644 is the red one. 13H8304 is the black one. 88G580 appears to have disappeared. 13H5602 is a black one and appears to be the correct one for the 2200. The Otter fan switch is URP1126. There were three and they all supersede to that one. Moss stocks it, so it's still available. Many six potters also have a manual over-ride switch as well, just in case.... Chris.
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Post by halkyon on Jul 27, 2022 17:40:52 GMT
Yep that looks like those fit to the A-Series that I'm familiar with too, likely all the same threads and likely similar voltage requirements. I shall investigate.
I note that my current instrument voltage stabiliser does not look like 13H3553/148876. I think I have a spare one of those (same as the Minor again) so will compare the voltage across them when on and the resistance.
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Post by dave1800 on Jul 29, 2022 5:11:54 GMT
Let me know if you need details of how to measure the "regulated" voltage, it requires a couple of additional components before it can be read by most meters as it is achieved by switching between the power voltage and ground and the temperature gauge averages out the time the power is on and off, known as pulse width modulation (PWM). David Yep that looks like those fit to the A-Series that I'm familiar with too, likely all the same threads and likely similar voltage requirements. I shall investigate......
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Post by halkyon on Jul 29, 2022 12:50:19 GMT
Ran down to MGOC this morning and picked up BMK1644/GTR104 and 13H5602/YCB000101EVA/GTR101. Tried both and they both over-read even compared to the existing sensor. So there goes that theory, or perhaps YCB000101EVA isn't a valid replacement for 13H5602 and GTR101 isn't a valid alternative to YCB000101EVA!
I'll try a genuine 13H5602 from a Land Rover supplier, but could it be the gauge itself?
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Post by dave1800 on Jul 30, 2022 0:46:17 GMT
It is possible the instrument voltage stabiliser contacts have fused closed. Easy to test with a voltmeter across the sensor with the ignition on. If the voltage doesn't turn on an off it has failed. Of course, the engine may actually be too hot!
David
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