Car overheating and trackday on Saturday

[wip3]

So I've had a problem with overheating for half a year now. The car runs fine but over the last 6 months it has overheated 5-6 times. Suddenly I realize that the heater is only blowing cold air and the temperature gauge shots up to the max. Hoses going and coming from the radiator are cold and it seems that there isn't any more pressure in the system as usually. 2 times the overheating has stopped and the heater has started blowing warm air before I've been able to stop, but usually I have to let the car cool down. Sometimes the problem disappears only if I let it cool down and then drive a few hundred meters.

Could the HCV cause this? I have understood that the heater should only blow hot air if the HCV isn't working. It's odd that the problem comes up so rarely... It has not done this during the winter and it seems to be related to hard cornering somehow.

edit: Just remembered that the fan doesn't seem to kick in at any time. Could it be related to this?

 

[quest63]

HCV's should not technically cause overheating problems.... but time and again they do. The HCV can fail in the hot or cold position.

However there could be other causes to your problems such as a faulty thermostat or your water pump not working properly

Personally I would start with changing the thermostat as its the cheapest and fairly easy to do.

 

[wip3]

It sounds weird that the water pump would work on/off like this. I'll try to change the thermostat and flush the system today.

 

[quest63]

Water pump might not work properly if the auxilliary belt was slipping. Also I read its possible at certain temperatures for the pump impellers to become detached from the pumps shaft or for the plastic impellers to break.


Alternatively have you removed your aircon pump? or power steering pump? I recently read about someones car Flying Scotsmans iirc that had removed one of these and due to the routing of the fiesta auxilliary belt was causing the water pump to run backwards.

When you change the thermostat and refill with water run the car on the drive with the header tank cap off for 20 mins till its fully hot and the thermostat opens and gently squeeze the pipes to encourage any air out of the system. Also make sure the heater control is set to fully hot so water circulates around your heater matrix.

 

[wip3]

I called a few garages and they suggested that air gets somehow to the system. Possibly head gasket. I haven't removed aircon or power steering. If the cambelt was slipping and the pump wouldn't work shouldn't it make a squeking sound or something? When it overheats there is only a knocking sound from the engine, but I think it's the valves knocking? It's going to a shop tomorrow so hopefully they'll figure out what's wrong :?

 

[quest63]

I called a few garages and they suggested that air gets somehow to the system. Possibly head gasket. I haven't removed aircon or power steering. If the cambelt was slipping and the pump wouldn't work shouldn't it make a squeking sound or something? When it overheats there is only a knocking sound from the engine, but I think it's the valves knocking? It's going to a shop tomorrow so hopefully they'll figure out what's wrong :?

Actually I said auxilliary belt not cambelt, your car has a cambelt and an auxilliary belt

good luck with it in the garage :thumbs:

 

[wip3]

I called a few garages and they suggested that air gets somehow to the system. Possibly head gasket. I haven't removed aircon or power steering. If the cambelt was slipping and the pump wouldn't work shouldn't it make a squeking sound or something? When it overheats there is only a knocking sound from the engine, but I think it's the valves knocking? It's going to a shop tomorrow so hopefully they'll figure out what's wrong :?

Actually I said auxilliary belt not cambelt, your car has a cambelt and an auxilliary belt

good luck with it in the garage :thumbs:

my mistake :lol:

I'll get a new HCV if the garage can't figure it out. We'll see tomorrow...

 

[quest63]

If you do make sure its a proper Ford one cheap ebay ones have a very bad reputation

 

[wip3]

Ya that I've heard of

 

[wip3]

One of the plastic hose connectors in the HCV was broken and that probably let air in the system when the cooling failed. Suprisingly Ford had the HCV in storage and I was able to replace it. Hopefully the problem is gone now. Fingers crossed

 

[quest63]

Your lucky the drivers side inboard hose connector on mine snapped a few days ago and dumped all my coolant all over my exhaust, I was lucky my dealer had one in stock as well.

Another of the connectors also broke when I was removing it.

 

[oilburner]

It tells you how common they fail that Ford always have them on the shelf!

 

[quest63]

Agreed,shouldnt complain really Ive nearly had the car 3 years now so Ive been luckier than many others

 

[wip3]

So... The car isn't over heating anymore, but now it's underheating at all times. The temperature gauge stays below 1/3 all the time and it feels like I'm not getting as hot air indoors as I should. I thought that I bleed the system properly, but maybe there is still some air in the system...

 

[quest63]

possibly, some members have said it took weeks to get rid of air locks.

Did you fit a new thermostat? possibly your thermostat is stuck fully open all the time and isnt allowing the engine to heat up

 

[wip3]

No I didn't. The temperature was fine yesterday. I'll need to try and get the airlocks off the system.