Td5 running cold.

[landy]

Hi all.

l had to replace my radiator in the Defender recently. It had been leaking at the end tanks for some time.
Prior to this it never had any issues running hot/cold. I just lost a little coolant each month.

I was was coming home along the Hume Freeway today and noticed the temp gauge just between the blue and the first white marker. No coolent leaks, hot smells or high under bonnet temps. The expansion tank was at the correct level, maybe 1cm low and top hose slightly pressureised and hot, but not to hot to touch. No signs of blowing past the cap.
the radiator was cold and so was the bottom hose. Heater was blowing hot air as normal.
i was stopped for about 40 mins and drove away. The temp gauge then returned to normal, just under half way and stayed there only a matter of minutes. It then went back to running cold.

I suspect the thermostat to be stuck open. Has anybody experienced these symptoms and what did you do about it.

cheers all

[Eevo]

replaced thermostat

[harro]

There is a 'restrictor' in the line to the fuel cooler.
Small alloy tube.
If this is not fitted or removed the cooling system will run too cool.

Paul.

[PhilipA]

IMHO the most likely explanation is that the temp sensor is faulty.

Over time the oil that invariably comes out of the front of the engine dirties the plug on the temp sensor.

The first action to take is to remove and replace the plug a few times and if possible spray the contacts with electronic cleaner spray.

Then look at the other things such as thermostat.
How do I know? It happened to me.
Regards Philip A

[landy]

There is a 'restrictor' in the line to the fuel cooler.
Small alloy tube.
If this is not fitted or removed the cooling system will run too cool.

Paul.

Thats been fitted. I did that when I replaced the radiator with the new type.

[landy]

IMHO the most likely explanation is that the temp sensor is faulty.

Over time the oil that invariably comes out of the front of the engine dirties the plug on the temp sensor.

The first action to take is to remove and replace the plug a few times and if possible spray the contacts with electronic cleaner spray.

Then look at the other things such as thermostat.
How do I know? It happened to me.
Regards Philip A

Regardless I'll replace the sender simply as a precaution, I'm sure it's the original one fitted. But that wouldn't explain the cold to touch radiator.
Ive tested the gauge it's all ok. So happy that the sender is reporting true value.

Im fairly happy that the thermostat is stuck open. I don't think it's the pump drive or it would be over heating. Coolent is being pumped around the system. But I don't think there is any restriction.
Im more hoping someone will say 'yeah mine did that. It's XYZ' like you.

Thank you.

[landy]

IMHO the most likely explanation is that the temp sensor is faulty.

Over time the oil that invariably comes out of the front of the engine dirties the plug on the temp sensor.

The first action to take is to remove and replace the plug a few times and if possible spray the contacts with electronic cleaner spray.

Then look at the other things such as thermostat.
How do I know? It happened to me.
Regards Philip A

It never fails to amaze me the knowledge that abounds these pages.

I asked a question and got the answer. I wasn't convinced but tried a new sensor as suggested by PhillipA and he was spot on. All back to normal now.
Thanks Phillip for sharing your knowledge. $20 for a new sensor and $100 saved on a Thermostat. Can't say fairer than that.
I owe you a beer mate.