I have seen this item discussed in the past on this forum. We have a 2006 1.4 Ltr Fiesta with the cooling fan failing to run. I have tested that the fan will run when given a feed, the relay and fuse are good, and the temperature sensor has been changed. The water pump is functioning okay. The temperature gauge goes halfway and no more. I have run live data, and the sendor reached 100 degrees at which point the expansion tank cap let go. I then thought that the ECU may be the cause, but I have now received it back with no faults. I have checked the head gasket and tested the coolant system to 15psi. So here I am, hoping that someone could throw some light on it for me. Many thanks in advance

Sounds like you need a new cap. It shouldn't release at 100c. If this is a single speed fan then it won't be switched on until 105c.

If it's a dual speed fan then it sounds like you're missing the low speed. In that case, check the resistor on the bottom corner of the fan cowling.

Whilst you are doing this, we have a Fiesta and Fusion of this ilk, and I have replaced both header tanks in the last couple of years, as they were showing stress lines - I don't know current price, but if you are still on the original, it might be prudent to have a good look.

The expansion tank has already been changed and the cap was replaced but leaked before the 100 degree point, but good suggestions thanks.

Hello there, i ve seen this topic and i have an important question for my 2006 fiesta 1.6 16v (fyja). Is any chaces to be single speed fan? I dont have resistor, cable to plug in resistor. In the relay case next to battery it is only one relay. The fan is working, when ac is on(obviously) and when ecu heated sensor reach 105. For this the speed fan is at the same speed. It is normal to switch on only whens is reach 105? Thought? Im afraid its dangerous for to run on this high temp. Thanks!

2 hours ago, Bling11 said:

Hello there, i ve seen this topic and i have an important question for my 2006 fiesta 1.6 16v (fyja). Is any chaces to be single speed fan? I dont have resistor, cable to plug in resistor. In the relay case next to battery it is only one relay. The fan is working, when ac is on(obviously) and when ecu heated sensor reach 105. For this the speed fan is at the same speed. It is normal to switch on only whens is reach 105? Thought? Im afraid its dangerous for to run on this high temp. Thanks!

Yes. That is correct for your car.

5 minutes ago, TomsFocus said:

Yes. That is correct for your car.

It will be helpfull to mount radiator from 2.0 st to keep it enough cool for trackdays? Appreciate it

10 minutes ago, Bling11 said:

It will be helpfull to mount radiator from 2.0 st to keep it enough cool for trackdays? Appreciate it

People with 2.0 ST track cars often fit aftermarket radiators to them. So I would not just use standard 2.0 ST radiator on 1.6 either.

You can also add a fan controller so you can choose the exact temperature the fan starts. Normally this would not be a problem but track driving is different.

1 minute ago, TomsFocus said:

People with 2.0 ST track cars often fit aftermarket radiators to them. So I would not just use standard 2.0 ST radiator on 1.6 either.

You can also add a fan controller so you can choose the exact temperature the fan starts. Normally this would not be a problem. But track driving is different.

Thats why i was concerned about. I will take this into consideration. Many thanks!