Engine Intermittently Overheating?

[FreqFace]

Hi, recently I noticed my engine keeps overheating, oddly it doesn't happen gradually, I can be driving around for 10 minutes, ill stop and suddenly the engine temp shoots up, but then it will 'cool' down again very quickly, which doesn't make any sense. The cooling fan is also quite audible and it never was before. I havent had a chance to look under the bonnet properly, but whats likely the problem? Also when I turn the heaters on full the temperature quite obviously changes considerably as the engine temp changes. It seems to blow out cool air and the engine temp shoots up and then it does the opposite. This happens seemingly at random while driving. what should I check for ?

[jmurray01]

Sounds like a head gasket to me... If the heater blower changes the temperature... Though being a fellow 1.25 owner those 1.25's would last to at least 200,000 miles before needing a new head gasket! Looks like your one's been used as a racing car by the previous owner... :(

I could be wrong though as I'm not a mechanic! But have seen head gaskets fail before with the same symptoms...

[mintalkin]

the most common cause of overheating on the fiestas is when the HCV(heater control valve)packs up, you can try removing the two pipes from the valve where they go into the bulkhead and join them togeather with a length of copper pipe and hose clip and then see if the car then overheats if it does not you have found your problem.

[FreqFace]

Also at first I thought it was just leaking coolant, which it was. I looked at it yesterday morning and it was empty (leaked), I topped it up again last night but this morning its still full (not leaked?), however it now the water looks dirty? How do I tell for sure its a head gasket?

[jmurray01]

Well if the water is dirty it's not been changed for ages and the engine pobably has corrosion in it... Probably on the HG...

[artscot79]

Well if the water is dirty it's not been changed for ages and the engine pobably has corrosion in it... Probably on the HG...

well theres a few options here the water is dissapearing while driving so either the pressure cap is faulty and the pressure is causing the coolant to come out the tank it will also boil as theres no pressure in it a new cap costs a couple of quid ide try that first.

if that shows no results then take the car for a drive now you want to park the car up with the engine running let it get nice and warm feel the top and bottom rad hoses are they both hot should be if top hose isnt its a blocked thermostat if top is and bottom hose isnt then its the flow so rad could be clogged up with rubbish inside or the water pump has failed which is what it sounds like no pump means the water isnt flowing as it should this will cause the coolant to boil and dissapear als o the hot air will be there from the heater then it will blow cool as the heat is taken out of the coolant also look into the coolant tank you should see water come through it.

from youre description ide change the cap then get it checked for a failed water pump before you do serious damage if it is the case youll get the rad flushed and new coolant put in just water will kill the engine as it will boil without coolant in it

[Eljan66]

My fan keeps coming on after 5 mins driving but does not over heat any idea why

[Martin-Fiesta-MK6-1.4]

12 hours ago, Eljan66 said:

My fan keeps coming on after 5 mins driving but does not over heat any idea why