Defender 300tdi temp gauge fault?

heuer27 · Mar 25, 2010

I have recently had a disaster with my defender and had to replace the engine.
As a result of this my temp gauge is reading faulty, I think.
When the ignition is off the needle sits at a low normal position. When the lead to the temp sender uint is earthed it returns to the bottom as normal . After running the engine the temp gauge rises and just about hits the red .After switching off the ignition again it falls to a low normal reading again.
I have changed the temp sensor and thermostat No joy.
Can anyone shed any light . The gauge was working perfectly before the engine killed itself ( failed oil pump).

wiltshire landyman · Mar 25, 2010

poor earth

tekwane35 · Mar 26, 2010

Heuer27
When the wire to the sensor ( in the thermostat housing ) is earthed , the guage should go full limit to the red.
Keep in mind that there are two types of sender unit for 300Tdi Defender , I don't know what the difference is , but one has a green plastic top and the other a black . Having the wrong one will make your guage do crazy things .Make sure the contact between the wire and the sensor is good and as always , check that all the earths are connected and clean . Your main areas to check earths is from the neg battery lead to the transfer case and one from your engine to the body .

heuer27 · Apr 5, 2010

Thanks guys, I've checked the earth to the sender and it hits the red as you described.
Its a green sender i fitted thats what was in the old one.
I got behind the dash and disconnected the gauge completely and it still read low normal. So i'm thinking its the gauge unless anyone can say different.
I've got a TD5 gauge will that fit right in. Looks different though i think its just the mounting.

heuer27 · Apr 11, 2010

Fitted new gauge and still overheated . Turned out the new thermostat was not opening and causing it to over heat . I didn't know the water pumps the wrong way from most other cars which caused a lot of stripping down and head scratching before working out what the problem was .Should it be an 88deg thermostat or 83deg seems you can fit both .

wiltshire landyman · Apr 11, 2010

heuer27 said:
Fitted new gauge and still overheated . Turned out the new thermostat was not opening and causing it to over heat . I didn't know the water pumps the wrong way from most other cars which caused a lot of stripping down and head scratching before working out what the problem was .Should it be an 88deg thermostat or 83deg seems you can fit both .

personnal choice

j3mym · Apr 1, 2013

Im having this problem, i have a 300tdi in an ex v8 disco 2, the engine gave up and i replaced it but now my temp guage is over reading, i changed the sensor for the original one but still reads the same, checked the stat thats fine, any ideas?

gramgramfirey · Apr 7, 2013

You need the black sender not green. Green is Disco and will not talk to the defender gauge. I had the same problem recently. Broke sender off in housing and replaced with the green one. Wrong one. You get that!

lanny man 90 · Apr 7, 2013

Earth cable from neg on battery has a clip type thingamajig (located by gearbox crossmember ) I had the same problem on my old 300 clean it with wire brush an reattach to chassis the clip might even need a hit with a hammer to tighten it back on to the copper

Defender 300tdi temp gauge fault?

heuer27

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