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2011 focus engine cool down when I turn on the heater and some coolant disappearing

113 Views 4 Replies 2 Participants Last post by  amc49
Hi all,

I have a 2011 Ford Focus 1.6 (1560ccm) CDTi. Last November, while driving on the highway, I noticed that the engine temperature was increasing. I immediately pulled over when the temperature reached around 80-100 degrees Celsius and stopped the car. I called a tow truck to take it to the garage, where they determined that the oil cooler was faulty and replaced it. Once I got the car back, I drove a few kilometres and noticed that the engine temperature was dropping on its own when I was waiting at red lights. I checked the coolant level and found it to be nearly empty. I took the car back to the garage, and they explained that sometimes extra air can remain in the system, causing the coolant level to drop. They assured me it was normal, so I decided to keep the car.

After a few days, before going anywhere, I checked the coolant level again and found it to be empty once more. Additionally, I noticed a leakage next to the thermostat. I returned to the service centre, and they replaced the thermostat. I took the car back, but after driving a few hundred kilometres, I checked the coolant level again, and it was gone. The initial service centre referred me to another service centre, suspecting a head gasket issue. Now I am at the second service centre, where they disassembled the entire engine to diagnose the problem more accurately. They realized that by taking everything apart, it would be easier to identify the main parts that needed to be replaced. Consequently, They fixed the head gasket then replaced the entire timing belt and water pump, all the filters (as I did the first time), checked the injectors, replaced them as needed, cleaned the EGR valve and all related components, and cleaned the particulate filter.

When I got the car back, it was running perfectly fine, with lower fuel consumption and smooth operation, except for one small issue. Whenever I turn on the heater, the engine temperature decreases, and after driving a few hundred kilometers, the coolant still disappears. I'm unsure if there's any connection between turning on the heater for cabin warmth and the coolant disappearing.

Does anyone have any ideas or suggestions?


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Can't tell the flag but they must have some real idiots doing work in that country. You just had an engine taken apart for possibly nothing if the heater core is leaking.

You are either leaking coolant or burning it, need to fix the issue.

Extra air only stays in the system if the person working on it has no clue, Ford cars self bleed all air out.

It is NORMAL for you to turn the heater on and have the engine get slightly cooler, they ALL do it. A heater on simply acts like a bigger radiator.
Thanks! I will ask a service to check it. Before they changed the head gasket they checked it (I trust them they fixing my cars since 2008). When I turn on the heater it's not getting just slightly cooler. I can actually cool the engine completely down (by the meter) in 5 min
That meter is wildly inaccurate, the zero on it is only a few degrees from where the blazingly hot full overheat is. The gauges haven't been linear in many years. The PCM uses them like an oil pressure,light that just seems to moderate in temperature, the computer just moves the needle slowly so it appears to function correctly.
To self bleed Ford uses way too many hoses. Commonly the leak can be underneath car, you crawl around and look at each hose for the stain telling you there is a slight leak there.
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