The most likely cause of overheating is a defective thermostat. Are you sure it is overheating as in normal operation it can run close to boiling point, is it actually boiling?

Hi, I read you post with interest, as my wife has exactly the same car (Fiesta Flight 51) with EXACTLY the same problems. No hot air - so I replaced heater valve (which worked temporarily), then saw what I thought was oil seepage from rocker head gasket and coolant leaking from inlet manifold gasket, so replace both of those.

The water in the expansion tank was viritually boiling and the top pipe into the radiator from the thermostat was seriously hot, so rather than prolong the inevitable (and Parkers Parts doing a good replacement radiator at £42.08!) I decided to replace the radiator.

Even with a new radiator, the water in the expansion was tank STILL boiling, so I then replace the Thermostat.

Figuring I had sorted all possible ills, I took the car for a short drive and the coolant in the expansion tank STILL boiled! ..infact it later boiled even at idle within 12 or 13 minutes, so something is really wrong.

When I took it for that short drive, the boiling built up pressure enough to force the spring clip on the bottom hose of the expansion tank to expand - and the ALL of the coolant in the expansion tank emptied (amidst plumes of white smoke as I was driving along) all inside the engine compartment!

I am now seriously puzzled. I don't appear to have any oil in with my water, so don't 'think' the head gasket is to blame, and water does 'appear' to be circulating, so I don't (with my limited skills) want to start tying to replace the water pump.

My guess is that replacing the head gasket may do the trick as it could the cause of super-heating the water, BUT also if the pump is not functioning 100% it may not be circulating the water fast enough to allow it too cool properly.

Throughout all of this, the old AND new radiators have remained cool enough to touch by hand (even when the expansion tank is boiling like crazy) and the radiator fan never comes on - but as the radiator isn't getting very hot, I guess that is to be expected.

If you cured your problem, you might be able to help me cure mine!

Any thoughts/help to resolve this would be appreciated, before I have to pay someone more clever than me to replace either or both the head gasket and water pump

Thank you!!

Hi thanks for the quick response!

The expansion tank is that hot that the contents are litterally 'boiling'. It isn't just bubbling due to gas pressure etc. Unfortunately Ford decided not to equip this car with a temperature guage, so all I can tell are levels of 'hotness' like 'seriously hot' (e.g. the expansion tank and the top pipe from the thermostat to the radiator are seriously hot!) or 'warm to hot' (e.g. the radiator and other pipes are warm to hot - but still not a problem to touch. The radiator is more hot at the top where the flow from the thermostat pipe enters the radiator - and the rest remains largely 'warm' - which I guess shows the radiator is doing it's job?!)

The only 'filler cap' on this car is that on the expansion tank. I DID think my problem was the water pump, but having disconnected the thin return pipe (which goes from thermostat back to top of expansion tank), I can see that water IS being pumped back up there - so conclude that the pump is working ok.

Everything remains the same, whichever way I turn this around and whether or not I have the thermostat in or out, so I am fairly set on the problem now lying with the Head Gasket. I am guesing the Head Gasket has split and is pushing hot compressed air into the coolent channel, effectively super heating the liquid ..although I still would have thought that it would then go back around the system and be subject to the radiator cooling it down...?!?

I am running out of ideas. i've asked a 'mobile garage' to come and do a pressure test to determine IF the Head Gasket is the culprit or not, so we'll see...

Thanks again.

Edited by KJ1812 on 23/01/2012 at 18:05

Hi. Problem fixed. Despite my having taken the return pipe off the expansion tank to prove to myself that thepump WAS pumping water ...the problem, infact the root cause of all heating problems on the car, turned out to be the Water Pump. ..Unfortunately for me, I was left with a choice of Water Pump of Head Gasket, and picked wrong, so I replaced the Head Gasked first. Don't get me wrong, it WAS a mess, the holes for the coolent to flow through in the Head Gasket were partially clogged or even completely clogged with the K-Seal I put in a month ago, but the root cause was the Water Pump.

In some stupid move to save money, Ford had decided to stop using a metal impeller and go for plastic instead. My plastic impeller was in bits, literally. (so was I when I go the bill!).

So winding the clock back, the heater packed up in the car, so I replaced the heater valve. That didn't really do the job, but I realised the expansion tank was empty. ..probably been driven on empty for quite some time (do bear in mind this is my wife's car, not mine!). Daily refills of Kettle's full of water became tiresome, so I tried and failed to locate any leak. I added K-Seal to stop the leak. I noticed while under the bonnet that the rocker head gasket looked like it needed changing, and did that easily whilst still looking for the coolent leak. I noticed the coolent had been leaking from the Inlet Manifold Gasket and had neither the time or experience to fix that, so i called in some hired help. Inlet manifold gasket replaced in 2hrs for £117incl VAT. Coolent loss stopped, but car now very clearly overheating. The hired hand said 99.9% certain to need a new Radiator. I did that. £42.08 from Parkers. Still no difference. Water boiling in expansion tank after 10 mins. I bought a new Thermostat. Still no difference. I checked all pipes, and came to the conclusion it was the Water Pump or Head Gasket. I 'proved' the Water Pump was ok (but it wasn't. ...what was flowing, was flowing due to heat/expansion and not 'pumping' as it should have been). I got the Hired Help back and we went for the Head Gasket. This was blocked and in a mess, probably largely due to age and the amount of K-Seal that had found its way to the holes in the gasket for the coolent to circulate, but as there was no real pumping going on, the K-Seal had just settled on those holes and started to do it's job of sealing holes - which it did too well...! With a lot of head scratching and many hours lost, we knew there must still be a blockage and went for the Water Pump. The impeller was in broken plastic bits, some of which I am sure are still circulating around inside the engine! £27 plus VAT got me a new Water Pump. Problems with over heating disappeared instantly. Interior heater still not working, but I can live with that for now. Total bill for yesterday's Head Gasket replacement (including Skim) and a new Water Pump, was a beer short of £500. Total for the above, including new Radiator Thermostat, gaskets, pump etc was around £730. Almost the value of the car I think!

..anyone want to buy a car? ;-p

Edited by KJ1812 on 28/01/2012 at 13:02

hi there hope i can help.. without confusing your car problems with other posts.. overheating can be caused by many things, so dont dive straight into faulty pumps or blown gaskets.. does the cooling fan come on?.. is their any engine managment lights on?.. do u have warm air come through your vents once the engine has warmed up and youv switched your blower/demister motor on?