Afternoon All - our '96 300TDI 90 has decided to pose a challenge for us..... Temp gauge is doing weird things - normally rock solid, takes about 5' running to get to normal running temp (showing about 2/3rds up on gauge) then stays there all solid.

However - the last few journeys the temp gauge has behaved as normal for the 1st 20', then the needle will start fluctuating wildly - heading way past the red zone, then back, flicking back and forth (never below the point of the normal running temp). Then, for no apparent reason, it will go back to the 'normal' position, before starting its 'flicking' at some intermittent point.

The engine is not running hot, there is coolant in the system.

We replaced the section of wiring from sensor to socket in the engine bay, no change.

Any thoughts? We were messing about at the back of the lighting binnacle (oil pressure sensor needed changing) so wonder if wiring could have been disturbed in that area.

Thanks
 
Afternoon All - our '96 300TDI 90 has decided to pose a challenge for us..... Temp gauge is doing weird things - normally rock solid, takes about 5' running to get to normal running temp (showing about 2/3rds up on gauge) then stays there all solid.

However - the last few journeys the temp gauge has behaved as normal for the 1st 20', then the needle will start fluctuating wildly - heading way past the red zone, then back, flicking back and forth (never below the point of the normal running temp). Then, for no apparent reason, it will go back to the 'normal' position, before starting its 'flicking' at some intermittent point.

The engine is not running hot, there is coolant in the system.

We replaced the section of wiring from sensor to socket in the engine bay, no change.

Any thoughts? We were messing about at the back of the lighting binnacle (oil pressure sensor needed changing) so wonder if wiring could have been disturbed in that area.

Thanks
Could be the temperature sensor. I think they screw into the top of the head. From memory, there are several types.

Buzz up LRP tomorrow and get one, they aren't a lot of money, so worth a try for elimination anyway.
 
Temp sensor is in the block at the front of the engine (left side) just below the thermostst housing.
A new sensor is less than a fiver ...
 
Sensors cheap and easy to change but after that it could be a bad earth
Gauge on my 300 tdi defender goes close to the red when I put headlights on !
 
Thanks for the replies. Looks like it was an intermittent earth issue. When we were sorting out the lights on the light panel I had noticed that the bracket holding the temp gauge in place was loose and the gauge was rotating. I didn't sort that out at the time, but this morning had a proper look - the threaded bolt through the bracket was not secured properly so the ring connector to the gauge was also loose. Have tightened everything properly and the test run had the gauge needle nice and solid.
😀
 

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