The_Licht

New Member
So I've a cold running TD4 Sport and after reading the forum I thought that my thermostat might be stuck open. I did the old Gates inline thermostat in the radiator top hose mod but the car is still running cold.
The cooling system has been bled but on a decent drive the temperature will not get over about 60 degrees (measured by electronic temp reader). The vehicle is fitted with the diesel heater unit which seems to run most of not all the time as well.
If it's not the thermostat what else could it be?
 
It's the thermostat. Are you sure the correct thermostat was fitted in the top hose?
The top hose thermostat mod has been used many times the TD4 engine, always giving a much more suitable running temperature.
 
Yes it's been fully bled, car has been used daily to commute. Tried pulling fuse on fbh as well as it seems to run constantly as well but that made no difference at all.
 
Yes it's been fully bled, car has been used daily to commute. Tried pulling fuse on fbh as well as it seems to run constantly as well but that made no difference at all.

The FBH is controlled by the environmental sensor (actually a 5°C electric thermostat). If the weather is hotter than 5°C sensor, then that has stuck closed, triggering the FBH to run. The FBH water jacket also has a sensor to monitor coolant temperature. This will fire the FBH burner, if the coolant drops before ~76°C IIRC. However even if the coolant is over the FHB firing temperature, the FBH fan will continue to run, providing the environmental sensor is telling it to.


You problem does seem strange though, as blocking the radiator top hose with a water thermostat, should cause the engine temperature to climb, so it's a shock that it's not.
 
Is that Gates thermostat the same as the Renault 5 one? That’s the one I used in mine and temperature was ideal after fitting. Details of mine:
 
I knackered the thermostat when pushing it in to the hose when I did mine, of course not knowing until it was all back together, got another, fitted that and it warms up perfectly now.
 
Water pump working fine and it's the gates thermostat. I was very careful fitting it but I think my only option is to renew the factory stat.
 
I think you must have another issue here. If the gates thermostat is working as it should and is in the correct location it will stop the water from flowing through the radiator until the engine reaches temp. If your engine is still running cold then the coolant is still going through the rad.
 
Just a thought. Do you have the blower fan at high speeds than No2? Setting the blower fan on speeds 3 or 4 will tend to draw more heat out the engine than it the engine can make, which will keep it below running normal temperature.
 

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