Thread: 200TDI possible over heating issue

Originally Posted by Alvedin

Hello legends,


1994 200TDI defender.

Daily driven 75km on highway to and from work.

I’ve been scratching my head for the past week trying to resolve a suspected faulty water temp gauge. For the past week it has been reading at max! Well past the final white line. This only happens when I drive for about 2 mins, as the engine is heating up.

Ive been checking before every drive my coolant levels and they are fine.

Radiator upgraded by previous owner. New viscous fan by myself a few weeks ago.

I’ve done some research on how the water temp gauge and sensor work. Of course it’s down the the heat transfer. I noticed when I touched the temp sensor to the water pump it would be extremely hot to touch. If this meant to be hot? Could this be effecting the gauge? I’ve really done the sensor but no change.

What am I missing?

I’m keen to take the defy on its first beach trip but very hesitant due to the heating issue

Maybe a thermostat issue?
Have you got a non contact thermometer to check the temperature

Economy Non-Contact Thermometer | Jaycar Electronics

If you can confirm the factory sensor/gauge is correct, that would be where to start

I would also look at installing a engine guard auxiliary sensor/alarm

ENGINE GUARD EG01-1Single Temperature Sensor Kit | Engine Guard


Gav

I second the thermostat theory. It could be as simple as the thermostat staying closed. It is easily changed. If you do opt to change it get the gasket aswell. You could take it out to check it and see if it is stuck closed. I had one that stayed open and I had no heat at all!
Defender Parts | Cooling System | Thermostat and Housing
You could also do something simple like flush out the cooling system with a bottle of radiator flush in case there is a blockage or a build up of crude. Seems unlikely with the new radiator etc but sometimes it is just a simple solution that works.

Another vote for the thermostat as the place to start.

Originally Posted by Gav 110

Maybe a thermostat issue?
Have you got a non contact thermometer to check the temperature

Economy Non-Contact Thermometer | Jaycar Electronics

If you can confirm the factory sensor/gauge is correct, that would be where to start

I would also look at installing a engine guard auxiliary sensor/alarm

ENGINE GUARD EG01-1Single Temperature Sensor Kit | Engine Guard


Gav

Thermostat replaced this morning but no change to the water gauge. Still ready extremely high. I’ve done some research to test if the gauge is faulty but I do not believe it is. My sensor is still getting extremely hot to touch. I’m attempting a full system flush as suggested. Fingers crossed.

Could it be a faulty water pump not pulling enough fluid through? Hmmm

Originally Posted by Alvedin

Could it be a faulty water pump not pulling enough fluid through? Hmmm

It's poss, but IMO unlikely, as they tend to go over time. But the impeller could have fallen off I guess. But the rapid heat up suggests a blockage of some sort which is why we thought thermostat. Being hot to touch is normal at operating temp. Think about your hot water in your house, it's likely set at around 60°C and I'll bet you can't hold your hand under it for long. Your car likely runs 20/30 °C higher.

Originally Posted by Alvedin

For the past week it has been reading at max! Well past the final white line. This only happens when I drive for about 2 mins, as the engine is heating up.

Can you clarify this? Does it only show HOT for those 2 mins? What happens then?

Originally Posted by Alvedin

Thermostat replaced this morning but no change to the water gauge. Still ready extremely high. I’ve done some research to test if the gauge is faulty but I do not believe it is. My sensor is still getting extremely hot to touch. I’m attempting a full system flush as suggested. Fingers crossed.

Could it be a faulty water pump not pulling enough fluid through? Hmmm

What Tins said

I’d be checking temp with a touch less thermometer to confirm temperature sensor/gauge
Stock gauges are reliably unreliable until after the fact (not just LR)


Gav

Originally Posted by Tins

It's poss, but IMO unlikely, as they tend to go over time. But the impeller could have fallen off I guess. But the rapid heat up suggests a blockage of some sort which is why we thought thermostat. Being hot to touch is normal at operating temp. Think about your hot water in your house, it's likely set at around 60°C and I'll bet you can't hold your hand under it for long. Your car likely runs 20/30 °C higher.



Can you clarify this? Does it only show HOT for those 2 mins? What happens then?

This issue has arisen since I replaced the snapped water pump housing bolts and replaced the viscous fan. Today I replaced my thermostats and did a bleed of the coolant just to make sure there wasn’t air in the system causing the issue. Next step is to do a full flush to make sure there are no blockages as you mentioned.

My temperate gauge reads HOT constantly. Well past the final white line. When warming the car up the temp gauge does not move. Once I begin the drive, the temp gauge rises straight up to full HOT. As if it was faulty…. I’d consider replacing with some VDO gauges but don’t want to do it unnecessarily.

Originally Posted by Tins

It's poss, but IMO unlikely, as they tend to go over time. But the impeller could have fallen off I guess. But the rapid heat up suggests a blockage of some sort which is why we thought thermostat. Being hot to touch is normal at operating temp. Think about your hot water in your house, it's likely set at around 60°C and I'll bet you can't hold your hand under it for long. Your car likely runs 20/30 °C higher.



Can you clarify this? Does it only show HOT for those 2 mins? What happens then?

I’ll get my hands on a thermometer tomorrow to confirm temps. Today I managed to replace the thermostat and bleed the coolant just to make sure there was now air effecting the reading. I didn’t get around the doing a full flush. But that will be a task for tomorrow. If the thermometer reads different from the gauge I’ll look into replacing with some VDO gauges.

The HOT reads soon after I set off with the car. When I’m idling, getting the car warmed up in the morning there tends to be no movement of the gauge. The reason I thought a faulty gauge was due to it ready beyond MAX temp. (Well beyond the HOT)