Engine Cooling Reservoir Fluid Is Bubbling

[fedorwar91]

Hi, just hoping someone could help out with a small problem

i encountered today with my ford fiesta (mk 4 - ghia)

when i was driving i heard a rattling noise under the hood, i pulled

over, popped the hood and found that the coolant level was extremely high

in the reservoir, bear in mind before i left the level was inbetween min

and max.

my theory is that the coolant mixture isnt correct: i topped up the

reservoir the other day but didnt add anti-freeze (you're ment

to use a 50-50 ratio anti-freeze and water right?), i didnt think

any thing of it until today.

has anybody encountered this problem before? if so what was wrong?

cheers for any help.

[andy64]

Hi,

If the fluid's bubbling but not boiling, it could be a blown cylinder head gasket - allowing combustion gases to escape into the coolant waterways machined within the block & head.

If the bubbling's caused by the coolant boiling, then it could still be a blown head gasket, or a blocked radiator or a hose which has collapsed internally - or something as simple as a faulty radiator fan.

Alternatively, if you topped up a lot (e.g. if the reservoir was empty!) then it could just be air bleeding out of the system - though the coolant level shouldn't actually change on a modern car due to the use of "sealed systems" unless it's leaking somewhere or getting into the cylinders via a faulty head gasket.

While you should never top up with just water - even in summer because antifreeze contains corrosion inhibitors which are essential for the alloy engines & heads used in modern cars, a minimum 50/50 mix is essential - this shouldn't cause bubbling (unless the lack of antifreeze has caused the radiator to freeze, causing a blockage making the engine boil...?)

Hope this is helpful!

[fedorwar91]

the coolant was boiling as well, there was a lot of heat being generated in the car

when i drove on the M4 today.

out of interest, how much would a head gasket cost to repair/replace for

this model fiesta, ball park figures?

thanks for the help btw!

[Lenny]

the post before this is very informal, although it may be worth a try changing your coolant, completly flush out the old and replace with ready mixed, and the glycol in your current could be low leaving it more water than coolant which would bubble, also check the inside of your engine oil cap if theirs a white or gray scum on it, that also means its your headgasket is going as water would be mixing with your oil.

also if the condition worsens and you find your coolant gauge is going high, turn off air conditioning (if fitted) and run the fan as high as possible on HOT to take as much heat off the engine as possible.

i always find eBay a good place to get a rough price on parts too, maybe try doing a search for a new headgasket seal their mate.

best of luck,

and please let us know how it goes.

[mikehaggis]

Hi, just hoping someone could help out with a small problem

i encountered today with my ford fiesta (mk 4 - ghia)

when i was driving i heard a rattling noise under the hood, i pulled

over, popped the hood and found that the coolant level was extremely high

in the reservoir, bear in mind before i left the level was inbetween min

and max.

my theory is that the coolant mixture isnt correct: i topped up the

reservoir the other day but didnt add anti-freeze (you're ment

to use a 50-50 ratio anti-freeze and water right?), i didnt think

any thing of it until today.

has anybody encountered this problem before? if so what was wrong?

cheers for any help.

Hi I have seen the other replies you have had and would like to suggest that you need to assess whether the fan is coming in at high temperature,as it sound suspiciously like the fan controller is not working. First off check the fan itself to ensure that it is turning freely and that there are no rough spots or noises. DO THIS WITH THE IGNITION AND ENGINE OFF sorry for shouting but if you don't you can lose fingers etc. if the fan starts! Secondly and again with the ignition key off turn the engine over by hand to see if the water pump is turning ok and if it is noisy as this could be the problem (rattling noise under bonnet followed by high temperature as you described it.

If these are both OK then start the car and run it until it gets to normal temperature and the fan should come in. It should start up and run for about 20-30 seconds to lower the temperatur and then turn off again so carry out the check three or four times to ensure it is working or not.

If all these points are found to be OK then it will indicte that the head gasket may be on its way out. Coincidentally you did not mention what kind of mileage you have on the car but a head gasket problem is more likely at higher milages especially if the car has had a hard life IE lots of stop start type motoring.

Hope this helps

Regards,

Mike.

[btmaldon]

Before you concider doing anything expensive, try changing the expansion tank cap for a new one. If the old one isn't holding the pressure the coolant will boil at a lower temperature. It also will not circulate properly and will give similar symptoms to head gasket failure.

I know a couple of people that had their head gaskets replaced at great expense only to find the car still overheated. I changed the cap and they were fine.

Good luck