Overheating problem

[Valawen9]

Hello! I drive a 2012 Ford Fiesta… A few months back I couldn’t figure out why the car was overheating. Started with small fixes and worked my way up. In the end the guy I went to changed the thermostat (3 times), cooling fan, water pump, radiator, and radiator hose. He also mentioned some sort of oil clog. Car ran great for about 3 months. Now I noticed once again, whilst sitting in traffic the A/C started blowing less cold and the high temperature warning light came on. Also the cooling fan would blow even after the car was turned off. It SEEMS like when the car is driving at a normal or higher speed the AC stays cold and the warning light turns off. Hitting traffic I had to pull over several times to let the car cool down. 3 mechanics have checked for head gasket issues and they all agreed that wasn’t the case. What is the culprit here? Another bad thermostat?? And if so what would cause 4 thermostats to go bad in such a short amount of time??

 

[Handy Andy]

The only thing you have not mentioned...

The condition of the radiator and its core - those fins.

When the AC fan kicks in - that is the same fan the Radiator uses to cool the engine - so if the AC for the PASSENGERS is getting warm, better check those front grills and their vent system - I've heard of the front air grille area having slats that may get stuck in a closed of partially open position - when the engine is cold these slats close down to let the engine warm up fast, then the slats begin to open allowing outside air to enter and flow thru these two (AC in front the Egnine radiator right on and to its back) cores get air thru them and take the heat away. (Your model may not have or use this to help the engine warm up - but some of the different trim lines this car has might use such a system)

So, check to see if you have those cooling system slats designed to be closed when cold, but open when it is warm - they are supposed to be fully open in 70 and above temperatures even when starting a cold engine.

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You may also want to warm up the car, turn on the AC so the fan kicks on - and take a stream of water and force water to flush out your radiator fins before other problems and winter sets in - this way - that gunk, bugs and road dust, cottonwood and pussywillow lint - moths and pollen - doesn't plug up your radiator or AC core preventing air from flowing thru to take that heat away.

 

[Valawen9]

Well… today the warning light came on regardless of traffic. So it seems my car is just full on overheating. Have to keep pulling over to cool down on my way to work.
Touched the hoses and they all seem warm or hot to the touch. Coolant level is fine. Radiator is not dirty at all.

 

[Handy Andy]

How long ago has the radiator been flushed?

That action also would help with your thermostat issue.

Unless your water pump has died - but you'd have no heat in the passenger compartment when you switch to heat, no heat will come out - then that tells you the pumps quit

 

[Valawen9]

Radiator flushed 2 months ago. Water pump is brand new.
Is it possible the warning light is illuminating and telling me the car is overheating when it’s really not?
I used a scanner app yesterday and the temp read 220°, but I don’t know if that reading could be false as well.

 

[Valawen9]

To clarify, heat in passenger cabin works fine.

Just double checked coolant level… it’s fine. Ran the car until the fan kicked on and the hose that’s supposed to get hot, did. So I assume this indicates the thermostat is operating?
The scanner showed the temp get up to 238°. Warning light did NOT engage. Turned the car off.

 

[Handy Andy]

The it is possible the radiator core is plugged - by corrosion and improper flush, but, to check- feel the top hose, it would get warm first, then bottom hose gets warm more slowly that the upper hose as the coolant circulated back into the engine from that open thermostat.

IF the top hose gets hot and the bottom hose stays cold or cool - then suspect plugged core.

Either way, if the sensor was damaged - it may need replacement - the numbers are quite high.

An infra-red thermometer can help verify the actual surface temp of those hoses - if they are less than 110C - the sensor might be faulty - but again, if surface temp of a COLD hose and the TEMP of the scanner read the same - then the THERMOSTAT might be installed improperly - has to be Spring Side in, with bubble/bell valve to the top of the casing.

To help, there are several threads about this similar issue...
https://www.fordfiesta.org/threads/2011-fiesta-1-4i-heating-issues.7565/post-16670
https://www.fordfiesta.org/threads/fiesta-1-4-tdci-overheating-problem.8359/post-21515
https://www.fordfiesta.org/threads/ford-figo-2014-model-overheating-problem.8499/post-22231

 

[Valawen9]

Forgot to mention... when I initially had all the components of the cooling system replaced, my mechanic told me I had the worst case of stop leak buildup he'd ever seen in all the years he's been working on cars. He replaced what needed to be replaced and then flushed as much as he could out.

After two months of driving the car with no overheating issues, is it possible that more of the stop leak could have made its way through the system and re-clogged it?

 

[scotman]

Is your heater putting out hot air when you crank it up on high fan speed and hot temperature? It’s entirely possible that the radiator core is blocked by excessive stop leak.
Considering the age of your Fiesta, it might be more practical to get a new radiator!

 

[Valawen9]

Is your heater putting out hot air when you crank it up on high fan speed and hot temperature? It’s entirely possible that the radiator core is blocked by excessive stop leak.
Considering the age of your Fiesta, it might be more practical to get a new radiator!

Yeah its definitely putting out hot air!
Also the radiator is brand new as of 3 months ago. Literally have replaced the entire cooling system with new parts.

 

[Handy Andy]

Hmmm....

Where is the best or easiest place to pour stop leak?

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Now this can create an even more difficult condition, you now have the container - its hoses, and that multi-port connect housing where this tank flows into it, thru the engine's thermostats outlet side, spreads out into the radiator, oil cooler, Heater core and all points south.

Not sure how they did a flush before - but looks like it may need to be done again - this time, removing the container and install a petcock on the lower hose to help drain and backflush this stuff out of there.

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Sigh...I've used this and more than once - so the bottle is good for any type of coolant but NOT ALL types of vehicles - this is a concentrate and if not used property - can plug up your car and kill the water pump you're trying to save.

I've used this on a Chevy Nova with a small block V8 - replaced the radiator when I got the chance to do so.

Did this to a Chevy Spint 3-cylinder engine - WAY TOO MUCH - coolant capacity was so small it plugged up in a similar fashion as to your car - required several days of long-term cleaner and several flushing's to remove it and then fix a bad water pump - spent more time and money cleaning up this mess than it was worth. (It's a concentrate - so use only as directed)

Start by emptying the radiator - then pour water thru the coolant tank thru the system then out the bottom - then use a long term cleaner to finish the job then flush it and all debris out similarly as described and then refill with proper coolant - that's all I can tell you - it's the process - don't skip steps! The longer you wait, the worse it can get.

 

[Valawen9]

Yeah that would be the easiest place to pour it. Still waiting to hear back from my mechanic as I dropped the car off yesterday. But after talking to him initially he seems to think another flush is needed.