Ford Fusion - Engine overheating

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Sun 18 Feb 2024 12:20
Ford Fusion - Engine overheating - rustonboy

Please can anyone suggest my best way forwards. My engine seems to be overheating as the coolant boils out of expansion tank and makes a mess. I tried a test this morning with a cold engine and coolant refilled to the maximum mark:

1) Started cold engine - still no leaks from anywhere after 15 minutes

2) Attached OBD reader to see temperature with engine running

3) Waited for temperature to rise and cooling fan to kick in

4) Thermostat appears to open okay as hose to radiator becomes hot

5) Temperature got to 101, still no fan, coolant starting to rise in the expansion tank

6) Decided to switch off engine - did so - fan suddenly kicked for just a few seconds

7) Restarted engine - temperature 99 - no response from fan

8) Coolant becomes increasingly agitated and then boils out of expansion tank making a big mess - but still no leaks from anywhere else

I do not know what to suspect first - any ideas would be gratefully received

Many thanks :-)

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Sun 18 Feb 2024 12:23
Ford Fusion - Engine overheating - rustonboy

Ooops, I meant to say

6) ... fan suddenly kicked in (i.e. burst into life)

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Sun 18 Feb 2024 12:27
Ford Fusion - Engine overheating - Andrew-T

Water pump ?

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Sun 18 Feb 2024 12:56
Ford Fusion - Engine overheating - elekie&a/c doctor
Petrol ,diesel engine size ??
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Sun 18 Feb 2024 22:30
Ford Fusion - Engine overheating - bathtub tom

Is this with the car stationary, or does it appear to overheat when being driven?

How long have you had the car? Any work been done on the cooling system lately? Could the cooling system need bleeding?

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Mon 19 Feb 2024 09:07
Ford Fusion - Engine overheating - rustonboy

Sorry forgot to mention:

Petrol 1.6 manual (2003 model). Problem occurs when driving and when stationary. Now limited to using car for short journeys, i.e. stop before boiling point.

This is a great old car - hard to find a cheap replacement. I suspect this fix will be beyond my expertise and/or meagre ration of free time, so I will probably have to invest in local garage support. But it would be good to know what I am likely to be hit with!

Many thanks for your time and advice :-)

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Mon 19 Feb 2024 09:22
Ford Fusion - Engine overheating - elekie&a/c doctor
Cooling fan on these cuts in at around 105 degrees. If the coolant is bubbling and throwing out the expansion bottle, then the system is not able to pressurise or you’ve got a flow problem. Possibly the radiator is blocked . Can you see return flow via the small hose , back into the expansion tank ? Also have you checked for even temperature across the radiator?

Edited by elekie&a/c doctor on 19/02/2024 at 09:29

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Mon 19 Feb 2024 09:32
Ford Fusion - Engine overheating - skidpan

When I first fitted a Zetec engine (a totally different 2 litre one but the cooling system was the same design as the 1.6) to my Caterham back in 2002 it had a very different cooling system to the x-flow. After a few weeks of perfect running it started "boiling" coolant out of the expansion vessel but at the time this happened no fan running.

Since it was a £100 engine form a sc***per I presumed it was the head gasket and simply bought a new one and replaced it, seemed fine at first but in truth no improvement once up to temp.

Solution eventually found, it was the cap on the brand new expansion vessel. A wise man told me they could be unreliable and asked if it had a paint dab on the cap, it didn't. The dap signified it had been checked, no dab no check. He advised I go the Halfords and look through their stock for a cap with a paint dab, found one and fitted it. 22 years on no more issues with the vessel.

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Mon 19 Feb 2024 13:10
Ford Fusion - Engine overheating - rustonboy

Thanks for your inputs!

Interesting to know that the fan is supposed to kick in at 105. Yes - can see coolant coming back into expansion tank via small black hose.

About the cap on the expansion tank. I did replace the whole expansion tank a few years ago (it was cracked and leaking), and had no trouble since then. This problem has started suddenly. Maybe the filler cap has become faulty - that would be a lovely cheap fix.

In the meanwhile I tried a few more tests this morning with a cold engine and coolant expansion tank refilled. I also undid bleed screw at top of radiator until coolant emerged, and squeezed top hose to radiator – it felt the same as bottom hose so assume full of coolant.

I went for a drive for 10 minutes then parked up with temperature at 65, and left engine running and monitored the temperature. I also checked and found that the heater was working okay.

Under the bonnet

1) The top radiator hose became hot, the coolant level in expansion tank remained steady.

2) Temperature got to 100 – still no fan – coolant level still steady.

3) At 104 with coolant slightly rising and agitated, I turned off the engine and the fan started immediately

4) After half a minute, turned engine on again and fan stopped immediately.

I ran the engine again so the temperature climbed from 95 to 102 – still no fan - turned off the engine and the fan started immediately and stayed on for about a minute.

So I think this means that the fan works and the water pump works, and the fan is triggered to come on when the coolant is hot, but only after the ignition is switched off!

Maybe it's just the filler cap, he said hopefully ...

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Mon 19 Feb 2024 16:06
Ford Fusion - Engine overheating - skidpan

and the fan is triggered to come on when the coolant is hot, but only after the ignition is switched off!

That is not right. The fan should come on when the ignition is on.

I have had some cars with fan timers that allow the fan to run after the engine is turned off because the action of the water pump not working after the engine is turned off allows little water circulation and risks cooking the head. Very odd the first time hearing the fan start after you have closed the garage door.

Some Zetecs have a two stage fan (read 2 speed) but pretty sure that is only the bigger ones.

Edited by skidpan on 19/02/2024 at 16:07

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Mon 19 Feb 2024 16:28
Ford Fusion - Engine overheating - elekie&a/c doctor
Usually only get 2 speed fan if the car has Aircon .
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Mon 19 Feb 2024 17:49
Ford Fusion - Engine overheating - rustonboy

I really appreciate your comments - many thanks :-)

This car does have aircon, but it does not cool the airflow (fixing it is sadly not be a priority). But I assume the second stage (higher speed?) of the fan would only be triggered if the air con was switched on?

I bought a replacement cap for the expansion tank (£7) as a hopeful thing to try. Will run the same test tomorrow morning with a cold engine and see what happens. I guess I am hoping the new cap will resist the pressure better and the fan will kick in at 105 with the engine running. Clearly it should, otherwise idling in a traffic jam would be impossible.

Interestingly, the air filter housing on top of the engine says DURATEC, but when this housing is removed you see that the of the engine head cover says ZETEC, so I guess it probably is a ZETEC engine.

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Mon 19 Feb 2024 18:15
Ford Fusion - Engine overheating - elekie&a/c doctor
If the ac was functional, then the low speed fan would come on when the ac is switched on . It probably doesn’t work. It may be an idea to get the slow speed working ( forget the ac) . This may make the cooling fan come on slightly earlier. 1.6 is the Zetec Yamaha engine you’d find in a Focus .
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Tue 20 Feb 2024 01:31
Ford Fusion - Engine overheating - edlithgow

This is newer than anything I have experience of, and may be computer controlled, but I'd assume the fan is still a conventional electric motor which you can jumper direct to the battery with bits of wire.

So I'd do that, disconnecting it first in case you fry your ECU or whatever your particular brain box is called, and ideally finding out which contacts do what.in case there is local duty-cycle controlled electrickey that could also be fried

This will (a) be diagnostically useful, because it will tell you if and what is working, and (b) assuming its at least partly working, it will optionally allow you to rig it permanently on, as a workaround which will allow you to use the car.

After that you can investigate how its supposed to be controlled, whether it is being or why it isn't. On ye olde worlde cars that I'm used to, there's a thermoswitch controlling a relay,which turns on the fan, but yours might well be more sophisticated.

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Tue 20 Feb 2024 09:27
Ford Fusion - Engine overheating - Andrew-T
If the ac was functional, then the low speed fan would come on when the ac is switched on . It probably doesn’t work. It may be an idea to get the slow speed working ( forget the ac) . This may make the cooling fan come on slightly earlier. 1.6 is the Zetec Yamaha engine you’d find in a Focus .

Quite likely the a/c has given up because it has never been 'serviced' - the refrigerant may have disappeared, perhaps because of leaks in the condenser. No doubt it could be revived at some cost, but that may not restore the fan's habits ?

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Wed 21 Feb 2024 21:36
Ford Fusion - Engine overheating - Railroad.
Cooling fan on these cuts in at around 105 degrees. If the coolant is bubbling and throwing out the expansion bottle, then the system is not able to pressurise or you’ve got a flow problem. Possibly the radiator is blocked . Can you see return flow via the small hose , back into the expansion tank ? Also have you checked for even temperature across the radiator?

The pressure in the cooling system is directly related to temperature. The hotter the engine the greater the coolant expands, and the higher the pressure. As the engine temperature falls the coolant contracts and the pressure reduces. The cooling system pressure is therefore regulated by the temperature. The pressure cap is an overall safety valve which will lift if the pressure exceeds around 0.9bar. A second valve in the cap allows air into the top of system to prevent vacuuming, so the hoses aren't sucked flat as the engine cools. The cooling fan will serve no purpose if the radiator is cold. The radiator should be hot at the top and slightly cooler at the bottom when the engine is fully warmed up as it gives off its heat to the outside air. The fan should only be needed when there is little or no natural airflow resulting in no heat dissipation. If the fan cuts in with the radiator cold then you have a clear cooling system circulation problem.

Edited by Railroad. on 21/02/2024 at 21:38

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Wed 21 Feb 2024 23:22
Ford Fusion - Engine overheating - Andrew-T

<< The pressure in the cooling system is directly related to temperature. The hotter the engine the greater the coolant expands, and the higher the pressure. As the engine temperature falls the coolant contracts and the pressure reduces. The cooling system pressure is therefore regulated by the temperature. >>

To be strictly accurate, 'coolant' expands as temperature rises, just like everything else, but the expansion of the liquid would be scarcely noticeable in the ballast reservoir. It's the rising vapour pressure of the water (1 bar when it boils) which lifts the relief valve if the engine overheats.

Once any air has been purged from the system, when the engine cools the vapour pressure reverts to 'normal' - about 0.03 bar at 20°C. That is what could cause hoses to be sucked flat (tho I don't think I have seen that happen).

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Tue 20 Feb 2024 14:33
Ford Fusion - Engine overheating - John F

...4) Thermostat appears to open okay as hose to radiator becomes hot

5) Temperature got to 101, still no fan, coolant starting to rise in the expansion tank

If well warmed up with the thermostat open the whole radiator and the exit hose should be hot too.

Many years ago my son had an old Citroen Xantia with the OP's problem. The diagnosis was a failed water pump. Why? It had plastic vanes on the impellor and they had all gone rotten and disintegrated so the water was hardly circulating. Were old Fusion impellors made of plastic? Thanks to modern materials with minimal internal corrosion, unless someone has poured a load of 'radweld' into it, radiators never get significantly bunged up nowadays.

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Tue 20 Feb 2024 15:32
Ford Fusion - Engine overheating - rustonboy

Thank you so much for offering advice and wisdom - it's really heartening to be helped by strangers - restores one faith in mankind with all the s*** that seems to surround us sometimes ...

So good news - the problem is solved! And what's more it was indeed the expansion tank filler cap, making this possibly one of the cheapest repairs ever at £6.99.

Ran up the engine. At 102 degrees the coolant rose nearly up to the cap, so fearing the previous boiling out, I switched the engine off and the fan kicked in immediately as before. The coolant level dropped quickly - I restarted the engine straight away and the fan stopped immediately. The temperature had dropped to 99 in that short time!

I repeated the above with exactly the same results, suggesting that this feature is indeed an intentional precautionary measure when the car engine is turned off above a certain temperature (the fan was not activated when turning off the engine at 96, for example).

Then I decided to hold my nerve and wait until the engine hit 105. The coolant level was pretty high by this time, but the fan did kick in at 105 and ran for about 15 seconds. The coolant level dropped quickly and the temperature settled at 96. I kept the engine running and let the temperature rise to 105 again, with exactly the same results. So that cycle was repeating nicely, up to 105 then down to 96 with the fan kicking in for approx 15 seconds in each cycle.

This really is a great car, still strong and young at heart after 21 years and about 120,000 miles (the speedo drops out sometimes so not all the miles get registered - can tell the speed from the rev counter so it's not a big deal). We have had this car for 6 years and I want to keep it for ever :-)

As an aside, no response form the fan at all when switching on the aircon. It did not work when we bought the car 6 years ago, so maybe beyond help.

Finally, many thanks again for your help - I wish I could buy you all a drink - but instead will obviously do my best to help others whenever I can :-)

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Tue 20 Feb 2024 15:45
Ford Fusion - Engine overheating - Andrew-T

Ran up the engine. At 102 degrees the coolant rose nearly up to the cap, so fearing the previous boiling out, I switched the engine off and the fan kicked in immediately as before. The coolant level dropped quickly - I restarted the engine straight away and the fan stopped immediately. The temperature had dropped to 99 in that short time!

Assuming that your new tank-cap is holding pressure correctly, I still wonder whether there may be a residual airlock somewhere. At 105° there will be about 1 bar overpressure in the system, but without actual boiling the fluid level should not rise a great deal. Most ballast tanks have MAX and MIN marks - where did you fill to ?

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Tue 20 Feb 2024 21:14
Ford Fusion - Engine overheating - rustonboy

I filled up to just below MAX. The coolant rose well above MAX at its hottest, nearly reaching the filler cap, but I do not think it was boiling despite being over 100. It definitely boiled out of the tank with the old cap - loads of fluid lost, and maybe air got into the system when refilling the tank which then looked pretty much empty. I did bleed the radiator a few test runs ago, and could do that again. Otherwise, can you suggest how I might locate or release another airlock? Many thanks for the follow up :-)

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Tue 20 Feb 2024 23:07
Ford Fusion - Engine overheating - Andrew-T

I did bleed the radiator a few test runs ago, and could do that again. Otherwise, can you suggest how I might locate or release another airlock? Many thanks for the follow up :-)

Don't know about Fords, but most cars have several bleed points to be used when (if) coolant is changed (modern coolants are expected to last the life of the car). In particular the circuit to the heater may need a look. Now you have a system which holds pressure, you can drive normally and small amounts of trapped air should work their way into the overflow tank, so check occasionally when the engine has cooled to see if the level drops a bit.

While on the topic, I hope you are topping up with the correct variety of antifreeze for your engine.

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Wed 21 Feb 2024 08:09
Ford Fusion - Engine overheating - skidpan

The Ford 2 litre Zetec is a doddle to fill, pretty much self bleeds. Would not have expected Ford to design a system that has multiple bleed points but the OP should be able to tell us simply by looking.

But from memory the elephant in the room was the cheap plastic thermostat housing that replaced the earlier robust solid Bakelite type material and before that cast alloy. The plastic ones crack and dump coolant.

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