Duratec over cooling

[Mr MXT]

Thought this would be the best section, having trouble with my Duratec in a Westfield plumbed thus



previously, engine ran at 85-90 degrees with no issues, a holed rad meant I rplaced the standard old rad with a 55mm coolex.

Since then, when the engine gets up to temperature, if I hold it at WOT, the water temperature drops right down, can get as low as 40 if the road is straight enough....

I've changed the stat with no avail.

On the advice ofsome zetec owners I've drilled a small hole in the thermostat to get the flow going. This didn't help, the car ran at 100 degrees and warmed up worryingly fast..

I'veput an undrilled stat back in.

Any ideas ?

[andyf1140]

Have you tried the turbosport forum? They have a lot of experience of Duratec installations...

[Frankthered]

Is the water temperature sensor on the radiator, or in that part of the circuit?

If so, do you have a separate sensor on the engine?

If the water coming back from the rad is that cool, the stat should reduce the flow to the rad to keep the engine at its optimum temperature. To be honest, it sounds like your new rad has some additional cooling capacity that you didn't really need, but your stat should keep the engine happy.

[Mr MXT]

andyf1140 said:

Have you tried the turbosport forum? They have a lot of experience of Duratec installations...

No, but I will. Good shout, thanks.

Frankthered said:

Is the water temperature sensor on the radiator, or in that part of the circuit?

If so, do you have a separate sensor on the engine?

If the water coming back from the rad is that cool, the stat should reduce the flow to the rad to keep the engine at its optimum temperature. To be honest, it sounds like your new rad has some additional cooling capacity that you didn't really need, but your stat should keep the engine happy.

Temp sensor is where the coolant exits the head. I only "upgraded" as I had a hole in the previous rad, I wasn't suffering any overheating issues even when on track for 40 mins at a time.

You can see in the diagram, there is a bypass that circulates the coolant back to the head when cold, to speed warm up, then the stat isn't open / close, it bypasses the bypass, so the coolant flows round the rad once warm.

Its as if the stat doesn't close quick enough, so the engine gets a massive glug of cool coolant that has been sat in the rad....

[Frankthered]

Is the stat electronic or mechanical?

I understand you needed to replace the rad because of the hole, but it seems like you've upset the balance by putting some additional cooling capacity in the system.

If the stat is controlled by the ecu, is it possible it could be programmed to go fully open when the throttle is fully open? (Once everything is up to temp, that is.)

[andyf1140]

I've got a similar problem with a Pinto. The stat lets the engine warm up to 85-90 and then opens and the temp drops to 75-80. This is a mechanical stat so it can only be that it's sticking although I have seen others have more extreme results when they have put the stat in the wrong way round.

[Chris-S]

I had some pretty weird behaviour on the Westy with a Zetec after I did some work on it and it was all down to an airlock. It was a while back, but ISTR it appeared to be warming up OK then apparently suddenly going cold again. I realised it was just that there was no water reaching the temp sender. Took some messing about jacking the car up to shift the airlock but has been 100% ever since. Warms up fast, stable temps under all conditions, fan works as one would like and expect.

[andyf1140]

Perhaps taking the temp sender out would allow the trapped air to escape if that's the problem.