Ford Focus II, 1.6Tdci, 2005 - Ford Focus overcooling - acr75

The temperature gauge will gradually increase until it reaches just below 90C (88C or so). Shortly after this temperature is reached, it will drop suddenly to about 75C and then never reach proper operating temperature (88C) again. I have also noticed the engine cooling fan will be running a lot.

I checked the top hose of the radiator and this stays cold for a while indicating that the thermostat is closed to start with and then opens. As far as I am aware, ECU, thermostat or AC pressure switch control operation of the fan.

The local Ford dealer said that a re-program of the ECU could cure it, so I will give that a try. Any other ideas?

Thanks

Ford Focus II, 1.6Tdci, 2005 - engine overcooling - acr75
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Ford Focus II, 1.6Tdci, 2005 - engine overcooling - acr75

PCM repogramming had no effect. This would leave a slow closing thermostat, faulty gauge or faulty temperature sensor. Anyone with any experience of how the water temperature normally varies in a 1.6 Tdci (Ford)? Is what I am experiencing normal?

Ford Focus II, 1.6Tdci, 2005 - Ford Focus overcooling - Dieselhead2

My focus does something similar. The coolant never gets above 57C and the heater output is lukewarm (bad in winter)

I just tested my thermostat in a saucepan and it opens correctly (starts to open just above 80)

Does anyone know what the other output is from the thermostat housing? EGR cooler?

Ford Focus II, 1.6Tdci, 2005 - Ford Focus overcooling - Collos25

One reason for the car not reaching temp is a faulty thermostat but you say you have tested the part another causes are a blown headgasget this can manifest in many different ways depending on how its blown or it could just be very low on coolant due to a leak.The reason for a working thermostat to give a wrong reading in a car engine is there is no liquid present and its trying to operate in air,

Edited by Collos25 on 30/12/2013 at 20:47

Ford Focus II, 1.6Tdci, 2005 - Ford Focus overcooling - Peter.N.

Direct injection engines are very thermally efficient so if you have the heater on in cold conditions it can use more heat than the engine is producing. Try the effect of turning the heater off and see if the temperature rises. My C5 and 406 have auxiluary diesel powered heaters fitted, I suspect yours may also have one. If you get warm air from the heater long before the temperature gauge starts rising that will be why. My cars never reach full working temperature this time of the year unless you are pushing them hard.

Ford Focus II, 1.6Tdci, 2005 - Ford Focus overcooling - Collos25

Then there is the wrong thermostat fitted it should reach operating temp even in the coldest climates.

Ford Focus II, 1.6Tdci, 2005 - Ford Focus overcooling - Dieselhead2

Thanks for your answers guys. I changed the thermostat with a non-ford one and it's even worse than before! I may chyange it back.

Anyone know what the hose coming off the back goes to? It's not the heater or EGR cooler. It appears to be thermostatically controlled by the other end of the stat; mine is wide open.

Ford Focus II, 1.6Tdci, 2005 - Ford Focus overcooling - Dieselhead2
Might block off that third port and see what happens

stuff a bit of rag in it or something
 

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