Water running temp is cold

rkeil

Member
Hi I drive a 1.4 TDi which I have had for 15 years and fast approaching 300K.

The water temperature gauge beauty moves from 60. and the heater does get warm but I remember it hotter! When I am stuck in traffic slowly the water temp gauge creeps up to 90 and then the electric cooling fan comes on, as it should.

I have changed the thermostat and it worked properly straight away, but in less than two weeks it was back to running cold.

Scratching my head on this?
 

rkeil

Member
I did check the original thermostat in the kitchen and it opens and closes as it should. Just home and the car just cold, dipping finger in expansion tank the water is warm and the radiator is stone cold, pipes are all warm but not hot.

If pump was faulty, wouldn't; the car run hot?
 

Robin_Cox

Member
Could there be an airlock in the top of the radiator? - there is a vent for this at the top right-hand side (as you look at the car from the front)
 

spike

Well-Known Member
Cold running can be caused by the thermostat not sealing correctly and allowing cold water to leak through the stat.
In winter it does not take much flow to prevent the engine from reaching operating temperature.
The 'pan' test is fine for checking the opening / fully open temps but there is no easy way to check how well the stat seals when cold. Maybe a visual check with a light would show if the disc has good contact with the stat body
Even trickier to check is how well the stat locates in the thermo housing which could be another leak source

Cheers Spike
 

rkeil

Member
Took stat out again and found a small piece of plastic holding it open. (i think broke from the plastic housing) removed and so far all working again.
 

Howey

Member
Took stat out again and found a small piece of plastic holding it open. (i think broke from the plastic housing) removed and so far all working again.
Mega!
On a different subject have you ever replaced your oil pump chain/tensioners and which tdi engine have you got 75 or 90 bhp?
Glad you got a good result!
Cheers
Howey
 
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