Series 3 Temperature gauge reading hot

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Re 10v vs 12. The 12 v supply varies with battery charge so to get the gauges to read the same regardless of battery charge they run on a 10v supply. There's a liitle box behind the dash that has a heater coil and bimetallic strip (its VERY low tech) and it averages 10v. The gauges should come off of that, but I have a feeling the oil gauge does not but tempand fuel gauges do. Follow the wires. voltmeter wont work as its an average 10v and the voltmeter will jump all over the place from 0 to 12.5..
 
Welcome to the joys of old Land Rovers!
A laser thermometer will give you some peace of mind that it's not actually overheating, then you can spend the next few days/weeks/months figuring out why the gauge is wrong...
If your engine is from a 90/110, it should have an 11H engine number, in which case it may have the wrong temp sender. I don't think you can identify the sender just by looking at it, but a non-genuine Series sender is cheap enough to try. The threads are the same on the Series and early 90/110 senders.
IMG_0703LR.JPG
If that doesn't fix the problem then it could be the gauge itself, or the stabiliser, or the wiring. If the wire to the sender is shorted to earth, the gauge will go to max as soon as you turn on the ignition. Does the gauge read zero if you disconnect the sender?
 
I bought a "laser guided" temp gauge for very little on Ebay and it is great for seeing the temp of hose and thermostat housing etc, and seems very accurate. I can also tell now if my son is bullshirting me when he says he has a temperature and wants a day off school.
 
Hi everyone, thanks to all for responses and help/advice. So, managed to find out my early Landrover 90 engine had a 5/8 thread on the temperature sender. Contacted mini spares who checked and confirmed their capillary gauge was 5/8 as well. Here’s it fitted, working well and yesterday it showed my running temperature to be between 80° and 90°.

As you can see, I’m used a wee bit of PTFE on the thread; wasn’t sure if this was needed but wanted to be safe. Fed the sensor through with the speedo cable. The bracket was originally right angled for mounting on a horizontal surface but just bent it out so I could bolt it on like so.
 
That temp is fine. Looks like you have an 88’ c thermostat. Ok to 100’c
At least you can now spot any water probs easier than the normal gauge

Sort the pipe work between the heater matrix & front of engine. Otherwise it will rub on the HT leads ;)

Looking good
 
And now Highlander will know what his engine temp is :) while those who keep messing with old gauges [ that were not that good in the first place ] old voltage regulators and forty year plus wiring are still guessing.:(
 
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Hi all,

Apologies for reviving this thread but I thought I’d leave it here after battling with my own temp gauge

- Almost always sat just below the red
- Had various replacement thermostats and a new radiator, plus cooling system flush etc
- Fuel gauge fine
- Wiring pretty decent
- Meat thermometer in the top of the rad suggested all was well

After considering my life choices as to vehicle purchasing, I stumbled across some testing advice in a forum (can’t find it now, but thank you whoever it was!)

A suggestion was to check the gauge by earthing the sender to the block which should cause the gauge to go to the top with the ignition on. It did — leading me to think that it was the sender.

However, I noticed the sender connection looked grubby — not surprising given I do take it off road etc. Gave it a clean up, and suddenly all was well!

No clue how this works, as electricity is a dark art to me — but I hope it helps someone else out who may be scratching their head too!
 
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