My 2009 1.6 petrol automatic Fusion has a cooling problem. 

It overheats intermittently. It can be fine for a week or two then will suddenly overheat as follows...

When driving, the temperature gauge sits at around 90 degrees, pretty rock solid. The car heater though is blowing only cold air. Then very SUDDENLY the temp gauge will shoot up to >200 deg and the warning light will come on with message ENGINE TOO HOT and there's steam coming from the coolant expansion tank etc. Leaving the engine off to cool, then topping up coolant and restarting the car, it will run fine again for a week or two.

It  happens when I'm not on dual carriageways/motorways - as the weather is currently cold I'm guessing the flow of air is keeping everything reasonably cool at constant high speeds. But like I say, can be fine around town too for a week or two.

Funny thing is after these overheating episodes the heater blower starts blowing nice warm air.

Then the cycle repeats.

I've had a full electrical diagnostic run and the 2 stage fan, temp sensor etc are all working perfectly.

I'm thinking maybe a blockage somewhere in the cooling circuit or maybe the water pump isn't working properly. Any ideas?

I would consider the thermostat first, sticking.

Also consider air trapped in cooling system, which i think requires running car (static) with coolant tank lid off and heater being switched on. I think that was what i read up on at the time, i was expecting to have this problem like other fusion owners had, bit i never did.

Imo, i don't think it would be water pump, as this is belt driven, mechanical device would be either good or bad.

Out of interest when was water pump / cam belt replaced ?

If i am wrong, then there are more experienced members who will correct me.

On 1/11/2025 at 11:45 AM, fullwavebridge said:

I would consider the thermostat first, sticking.

Also consider air trapped in cooling system, which i think requires running car (static) with coolant tank lid off and heater being switched on. I think that was what i read up on at the time, i was expecting to have this problem like other fusion owners had, bit i never did.

Imo, i don't think it would be water pump, as this is belt driven, mechanical device would be either good or bad.

Out of interest when was water pump / cam belt replaced ?

If i am wrong, then there are more experienced members who will correct me.

Thanks for the reply,

Both thermostats have been changed already. I will try bleeding it to see if there's an airlock.

If you're getting no warm air through the heating system then suspect an air lock (if you know the thermo is good)

Could also be a fault not telling the fan to come on

The cold heaters is the interesting part.  The thermostat shouldn't affect those.  Is there a heater control valve on this model/engine?

1 hour ago, TomsFocus said:

Is there a heater control valve on this model/engine?

Not that I am aware of.

25 minutes ago, Paulkp said:

Not that I am aware of.

That suggests a large airlock, possibly caused by a cracked heater matrix leak, or a faulty waterpump to me then.  The heater inlet hose is usually just after the waterpump on most engines.  Though I am baffled why it's only happening occasionally.

Yes, could be waterpump

So is it possible seal / gasket on water pump is leaking ? sucking air in thus creating air lock in the cooling system ?

Or even a bad hose joint, or as Tom suggests a bad heater matrix.... would it be worth checking under carpets for a possible leak too...

Thanks for suggestions everyone. As there are no leaks that I can see, I'm going to change the waterpump (pretty cheap part) and see how it goes.

I'll report back when I have a result.

13 hours ago, Trev1981 said:

Thanks for suggestions everyone. As there are no leaks that I can see, I'm going to change the waterpump (pretty cheap part) and see how it goes.

I'll report back when I have a result.

The waterpump is cheap but it's not an easy job on these.  For some reason Ford decided to fit it behind the timing belt, even though it's driven by the auxiliary belt.

I had a cracked expansion box on the thread for the cap. Intermittent on over heat errors but you could feel the heat when it was ran for a while. Do you always have to fill up the coolant? It's going somewhere,