Series 3 Should the temperature gauge usually move much when driving?

If it's the original gauge it is suspect number one, followed by sender then wiring.............. bin the lot, avoid another [no doubt Chinese] electrical gauge and get a traditional, mechanical gauge made by Durite or Tim - £30.00 or so, done job and suits the vehicle.......................... good luck, you're symptoms suggest dodgy gauge rather than overheating motor - does the heater run hot? [as hot as a LR heater can!] If so all is probably fine............

The heater does work fine.

I replaced the sender and wiring when I rebuilt the vehicle.

But not the gauge? your choice but I'd go mechanical.........

Your title / question is very open as it will depend on the air temperature, the terrain the load in the vehicle etc.
What is the issue ie is it boiling .
Is it fitted with a voltage regulator as that can chjange the reading depending on whether it is working and or your battery and charging systems state.

It isn't actually boiling, the gauge just seemed to me to be reading high.

There is a voltage reguator fitted. I remember reading on here that the fuel gauge will also vary if the regulator is bad. The fuel gauge seems fine.

I had a look at the Durite gauges on ebay. How does the union nut seal around the probe? That isn't clear from the photos.

Bobsticle said:

I just got one of these. The sender sits under a tie wrapped piece of closed cell foam on the top radiator hose. The red one is good in daylight and not too bright at night. I did have to extend the sender cable.

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I ordered a couple of those thermometers, they finally arrived this week.

Did you connect them straight to a live terminal in the dashboard for power?

Webley1991 said:

I ordered a couple of those thermometers, they finally arrived this week.

Did you connect them straight to a live terminal in the dashboard for power?

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As far as I can remember. I do have a lot of other things that are voltage sensitive and are recommended to have no more than 12v so those are fed off some simple regulators I soldered together but Im pretty sure the LED readouts go straight to available voltage. The LED voltage readouts that are very similar obviously need to read the voltage as is, so the temp readout should be the same.

Thanks for the reply.

What components did you use to make the regulators?

Webley1991 said:

Thanks for the reply.

What components did you use to make the regulators?

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Read this its good for LED switches and the like that would blow at 14v from an alternator. I just followed the diagrams and got the bits from ebay china.
http://www.reuk.co.uk/LM2940-12V-1A-Low-Dropout-Regulator.htm

This was my post bag from ebay and one regulator I had made up in the centre of the picture.

Thanks for the reply. I wired one up to the map light socket over the weekend and it worked fine without any kind of regulator.

The temp never got above 65 degrees with the vehicle sitting still and ticking over. I didn't have time to take it out for a road test.

I took it out on a run today and it seemed to average around 65 degrees all they way. It touched 70 a few times but nothing above that. There doesn't seem to be any cause for concern.

Temperatureis to low not good for your engine,

They were the readings from the digital thermometer with the probe mounted on the metal of the radiator inlet.

The readings are in degrees centigrade, not farenheit. 70 c doesn't seem too far out as I have a 74 c thermostat fitted.

Yep............. Mine sits at the same when moving but I dont have a fan on the engine so when in traffic it goes above 75. Thats when I flick on the electric fan. I was going to fit a thermostatic switch but its fine as is.

One thing that nobody's yet mentioned...

Webley1991 said:

Something I noticed was that the temperature gauge did seem to move a fair bit.

When running for a while it would hit about 2/3rds of the way up the gauge and stay there, but would drop when driving with the engine at lower RPM.

Is this normal for a Series? I'm comparing it to modern cars where the gauge usually sits at a certain point once the engine is warm and doesn't change much.

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Modern car temp gauges don't actually tell you the temp. They're ECU-driven, and really just say "Cold - Normal - Hot". The needle will sit stationary all the way between the thermostat closing/opening temp and (quite probably the upper) fan switch temp.

74degC is really, really cool for a car cooling system - most thermostats are up in the low 80s. The thermostat sets the lower bound for the normal operating range, the fan switch (on something with an electric fan, obv...) sets the upper bound - so 82ish to 95ish would be a perfectly normal range. Pressure and the additives from the "antifreeze" range boiling temp from 100degC to 105-110degC.

Yes thats cars for you. Whats this got to do with series trattor engines that have run at this temperature since their inception in the 1940s.

I now have both meters for the coolant to and from the radiator installed. The meter on the pipe coming from the engine reads around 65 c when running. The pipe back to the engine seems to run between 15 and 20 c cooler than the pipe from the engine to the rad.

I am sure it also runs a few degrees cooler now I have the plastic fan fitted.

Running to cold not good for your engine.

It would probably read hotter if the sensor was actually mounted inside the block (which it isn't). Both are mounted on the outside of the metal radiator pipes. They are held in place with foam and cable ties.

I fitted a new thermostat, so that should hopefully be fine. I can't see any other reason why it would be running too cold other than a stuck open thermostat.