Help needed figuring out why my fiesta sometimes overheats

[BernardFiesta]

Hello, I would like to ask if anyone had this issue: My 2010 TDCI 1.4 diesel fiesta sometimes randomly overheats. It happens in any weather conditions and temperatures from -12 C to +20 C and also it can start literally any time. You just start to hear your fan spinning at max speed and it feels like the power is instantly cut in half and the car can barely start moving. ( It requires 2K rpm from standstill). and the stupidest thing is that my fiesta doesn't have a temp gauge so I pretty much have no idea of actual engine temp. Any ideas? Thanks!

 

[econoboxrocks]

Sounds like a failing thermostat, or something has gone wrong in the electronics.

 

[Handy Andy]

IF you have a lot of miles on it - the thermostat might be stuck closed - so no fluid can get out of the engine into the radiator to help cool the engine.

You have other places or things to check...

Does your heater work? IF it's slow or little to no heat, it could mean the water pump is going out. No fluid to circulate heat or even move to heat your heater core to provide cabin heat. That means water pump is going out or bad belt / pulley is not turning the pump

OR your coolant tank has lost it's seal.

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• See that "orange color" container in the upper left?
  • That is your coolant reservoir.
  • It uses a cap and if the coolant is discolored or low,
  • it could be that the tank is failed, it can't hold pressure, or has oil mixing in from a bad/failed head gasket.
• Also possibly means your Water pump is going out - or hoses or radiator is leaking

So your system overheats because the coolant is low, or has no pressure or circulation to help with cooling.

Do you smell hot radiator fluid?


The "random part" can mean many things - better check the system to make sure the engine is getting cooled, you'll have to feel the hoses - just watch for and keep clear of moving engine parts but you'll have to verify the hoses are not leaking - you have coolant and the system is pushing fluid thru the hoses to help cool it..

IF the above check out ok, then look at wiring - even a bad ground wire will "open" up a temperature sensor, that if not grounded - will send the wrong signal and the system thinks it's overheating.

 

[BernardFiesta]

Thanks for such a detailed reply, My car has around 200 000 km or 124274 mi on the clock. My heater does work, although it takes quite a long time to heat up when it eventually does it works quite good. ( When the random overheat starts it works even better My coolant and its reservoir seem ok. My car doesn't leak, when I tried to check the hoses everything seems to be fine.

 

[Handy Andy]

Ok, seems to point back to a bad thermostat.

The Heater "Works really good" when it "overheats" so that tells me the "slow response" from previous may mean the thermostat is not working very well anymore.

It would stick open letting some coolant leak thru, now it's not regulating even on that - so it or the water pump? You say - you have heat so that rules out the water pump (for now)

200,000 km / 124,000 + Miles is pretty good!

 

[BernardFiesta]

I guess i can just replace the thermostat. I hope they don't cost a lot D

 

[Handy Andy]

Cheaper than another engine.

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Runs less than $20 USD - add in shipping...

RT - 1211 190F - 87C

 

[BernardFiesta]

Well, that's quite cheap, I'm just going to order it and replace it. Thanks for the help!