Thread: Rebuild Auto Gearbox now Engine runs cold

Could just be a coincidence, thermostat stuck open??

Have you checked if the motor is actually cool rather than just showing it on the gauge?

I'm not sure about the TD5 disco 2. But normally the auto transmission fluid is cooled also by the radiator. In order to rebuild an auto it would also mean the coolant would need to be replaced.

I'd make sure the correct coolant was used as engines don't like having the wrong one. I think the TD5 uses the pink coolant. If it is green i would stop driving it until you are sure it is correct.

The thermostat could be stuck open, this may have happened simply because the coolant was drained and it was on the way out anyway. I would have thought it would be standard to change thermostat when draining the coolant. Maybe they changed it with the incorrect temp thermostat?

Another reason could be the auto has been running hot for a long time so someone change the thermostat to a cooler one to compensate. Now the auto is fixed the engine is running too cold?

Hope that helps. You will need to do some research to find out what coolant is required in the TD5 and the correct value temp thermostat. This forum should be able to answer these questions for you. You will also need to find out exactly what the auto rebuilder did.

Actually ignore below it is incorrect for me to say the needed to drain the transmission fluid. It would not be required. I had a brain fade as i'm unwell. But the other info still stands.

Originally Posted by Jazzman

I'm not sure about the TD5 disco 2. But normally the auto transmission fluid is cooled also by the radiator. In order to rebuild an auto it would also mean the coolant would need to be replaced.

I'd make sure the correct coolant was used as engines don't like having the wrong one. I think the TD5 uses the pink coolant. If it is green i would stop driving it until you are sure it is correct.

The thermostat could be stuck open, this may have happened simply because the coolant was drained and it was on the way out anyway. I would have thought it would be standard to change thermostat when draining the coolant. Maybe they changed it with the incorrect temp thermostat?

Another reason could be the auto has been running hot for a long time so someone change the thermostat to a cooler one to compensate. Now the auto is fixed the engine is running too cold?

Hope that helps. You will need to do some research to find out what coolant is required in the TD5 and the correct value temp thermostat. This forum should be able to answer these questions for you. You will also need to find out exactly what the auto rebuilder did.

No need to drain coolant, but they would have disconnected the trans cooling lines, still doesn't account for a temp drop

As already said check actual temp and thermostat operation