OscarBoy

Member

• Apr 26, 2024

• #1

Hi,

The temperature gauge on my Defender 110 300 Tdi 1997 is not registering any heat on the temperature gauge.

I tested the thermostat and that is opening with no issues. I also replaced the sensor on top of the engine thinking that might be at fault but that hasn't resolved the issue either.

Before I buy a new temperature gauge is there anything I can do to test the gauge or is there anything else I should also look that might be causing the issue.

I've seen threads about grounding the wire to from the gauge direct to the block but they seem to only have one wire from the sender to the gauge and mine has two wires (pink and a green). There are no sensors in the thermostat housing at all.

A side symptom of this is I am getting no hot air from the cabin blowers.

Any advice or guidance on what to do next would be very much appreciated.

Thanks in advance,
Mike

 

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miktdish

Guns n Chainsaws

Full Member

• Apr 26, 2024

• #2

Hi. That isn't the engine temperature sensor.
The engine temperature sensor is in the side of the engine just below the thermostat housing on the same side as the air filter box.

It has 1 wire going to it.
That wire has +12 on it.

 

OscarBoy

Member

• Apr 26, 2024

• #3

miktdish said:

Hi. That isn't the engine temperature sensor.
The engine temperature sensor is in the side of the engine just below the thermostat housing on the same side as the air filter box.

It has 1 wire going to it.
That wire has +12 on it.

Click to expand...

Thank you. I totally didn't see that one under there.

So is that the one I ground to earth to test it?

 

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miktdish

Guns n Chainsaws

Full Member

• Apr 26, 2024

• #4

Yes

If you ground the wire that goes to it, the temp gauge reads 100% hot.
Check there is 12V on the cable. This proves you gauge.
If the engine is hot and the gauge reads cold then you probably need a new sensor.

There are two types - a black and a green.

 

OscarBoy

Member

• Apr 26, 2024

• #5

I just shorted that sensors connector to earth and the gauge is working. So I will get a replacement sensor and hopefully that gets it sorted

 

OscarBoy

Member

• Apr 26, 2024

• #6

I've ordered one here. It looks to be the same.

Temperature sensor - 300TDI

AMR3321 Temperature sensor - 300TDI

www.paddockspares.com

 

tottot

Well-Known Member

• Apr 26, 2024

• #7

Find out why your heater is not working. 300's hate getting overheated due to the high water pump and possible air locks in system and first sign is no heat from heater.

 

Dippypud

Never Knowingly Understood

Full Member

• Apr 26, 2024

• #8

tottot said:

Find out why your heater is not working. 300's hate getting overheated due to the high water pump and possible air locks in system and first sign is no heat from heater.

Click to expand...

Usually a sludged up rad ... and or heater matrix .

Back flush to see what you get out ... too much rust and a re-core is the way to go ...

 

OscarBoy

Member

• Apr 28, 2024

• #9

I fitted the new sensor and everything started working, although it did seem to take a little longer than normal to reach operating temperature. To err on the side of caution, I will do a full coolant flush and replace tomorrow.