Fiesta 1.25 Zetec Strange Overheating Problem

[Reichl87]

Hi everyone,

I'm new to this forum and have decided to join as I am a ford owner and need some help with my 2000 Fiesta 1.25 and thought the best place to get help is here where people have experience with Fords.

Here is the story. I bought a 2000 Fiesta 1.25 Zetec from a friend. It had an overheating problem and it burst a pipe to the heater matrix. Before this was replaced my friend decided to pour a gallon of radiator seal into the cooling system. He must not have seen the very obvious gash in the pipe until very shortly after when all his radiator seal and coolant was under the car a minute later. He couldn't be bothered to try and fix it after that and given the actions he has taken so far, I think it was a smart idea - he is definitely not a DIY guy!

Here is what I have done with the car since I bought it:

- I replaced the pipe to the heater matrix. After this car was overheating. Obviously there was a problem with this in the first place for he pipe to rip.

- I removed the thermostat and tested it. It worked but it was totally blocked up with rad seal. I cleaned it off and put it back in. I flushed the system about twice after that as well. Engine still overheating.

- I tested the radiator fan. Works fine - turns on when needed and off when not.

- I then removed the radiator as I assumed it might be blocked. Sure enough it was full of rad seal when I flushed it out. I made sure water flow was good before I put it back in. Engine still overheating.

- I bought a new radiator because I thought I might not be able to fully clean the old one with all the rad seal in it. Replaced rad with new one - engine still overheating.

- At this point I though it must be the head gasket. So I decided to remove the head and replace gasket. When I did remove the head I noticed that there was a lot of blockage from the rad seal and I also found an old thermostat seal trapped in there. I cleaned out the head and removed all blockages. I noticed that the old head gasket did not appear to be damaged or leaking but at this point had to replace it anyway. I also had the head checked if it needed skimming - not necessary. I was pretty certain that the problem was with the blockage of the rad. I made sure to also clean the engine block of any old rad seal. Engine clean and new head gasket - engine still overheating!

- At this point I was kicking myself as I haven't yet checked the water pump and should have while I had the head off. But seeing the blockage in the head I was so convinced it was the problem I didn't even think to check the pump. Regardless one evening later I had the pump off and found that there is nothing wrong with the water pump. It was not leaking and all the blades were in tact and the turbine fan was tight and not lose on the shaft. So there is nothing wrong with my water pump.

This is the part where I am now lost and not sure what to do. The symptoms of the car are as follows:

Engine runs perfectly and warms up as normal. When idling it does not overheat it remains at 80C or whatever the optional running temp is. I can drive it slowly without too much going on with the temperature. But as soon as I get some revs on the engine, especially with heavy loads or up hills, when engine is working hard, the thermometer goes straight to red. When I ease off the accelerator it come down again after a while but normally I will turn off the engine shortly after. My heater works for a brief period. When I turn on the hot air it blows hot for about a minute and then goes cold. I checked the water level but I have not lost any water. This behaviour of the heater was what made me think this was all to do with the water flow in the system. Water in matrix heats up slowly and when I turn the fan on to blow hot air it cools down after a minute. But was flow in cooling system is fine!

So now I have taken this car on and it really should only have been a relatively small project. But somehow I am now stuck and not sure what to do next. This car was supposed to be for my wife. But she has since gotten herself a car. So this project is not about needing a car for work or domestic use anymore. This is now about my own pride and sort of obsession to overcome this problem which is currently beating me.

Any help or advice on this matter would be much appreciated.

[Stoney871]

!Removed! rad weld, more trouble than it's worth.

Have you checked the thermostat housing and the temperature sensor?

Also have you burped out any airlocks in the system?

[fiestaxr2i]

Hi max it sounds a bit like water pump to me, but also check the pipes to the expansion tank make sure they are not blocked.

[stef123]

!Removed! rad weld, more trouble than it's worth.

Have you checked the thermostat housing and the temperature sensor?

+1

the death of many an engine I'll bet

[ashghinn]

Would love to know the final result on this one, as I have exactly the same problem. Idles on the drive without overheating. Put her under load and the temp shoots up. Bottom hose stays pretty cold, even when water starts boiling and glugging. Flushed the radiator (seemed to have good flow), tested thermostat, felt the waterpump impellers (didn't remove it), no loss of coolant (cap holds pressure)...

yet she still wildly overheats now and then with lots of gargling coming from the "vent" pipe linking the head to the reservoir.

Any wisdom anyone?

[ashghinn]

Solved mine finally. My overheating issues were all down to the little Heater Control Valve. I'd heard talk of this causing issues with overheating but couldn't see how it would cause such a problem. My HCV was restricting flow and, as it is the only route for coolant leaving the block it was preventing circulation of hot water from the engine.

[wase16ll]

the fact the heater blows cold is telling you hot water isnt circulating through it....now just need to work out why.

could be a problem with the valve, or it could be the matrix itself...

you suggest water is circulating fine through the matrix.

but it could be only circulating through one of the channels of the matrix and others are blocked [for eg]....should add, exactly the same could be said of radiator.

if this was the case, then chances are its the rad seal causing the blockages, this gear should only be ever used to get you out of trouble, then flushed out at earliest opportunity, but going by your description, its been way, way overdosed on it. this will lead to blockages and air locks that wont go away till its been removed or seriously diluted down.

going by your description, think the best course will be to check opersation of heater valve, then flush that matrix out thoroughly, just keep pumping water through it in alternate directions, using one of those hose connectors to pressurise the jets could help but dont hsve it too high.

you could also temporarily bypass the heater in order to check the rest of the system is working as it should, pay particular attention to radiator once stat has opened, check for any cool spots.

[jeebowhite]

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[Phili Smith]

As alluded to by Ash, Have you checked the radiator cap (or to be acurate the expansion bottle cap)? if the seal is gone you don't get the pressure up and water boils more quickly. Might be a complete misdiection but I know a guy with a (new shape) Mini who was tearing his hair out with a similar issue, New cap problem went away! Not an expert on cars but been tinkering for over 30 years now and I had never encountered such a problem.

Phil