overheating?

[John]

The temperature gauge on my 1.3 City X is acting peculiar, it went right up to max without the water boiling and then moved around 3/4 to max with a short spell when it went down to 1/2. I don't think there is a blockage or air lock as the heater was still working. Could it be the thermostat, any ideas anyone?
Ps The engine did seem hot so I think the gauge is genuine.

[E_T_V]

Quite possibly the thermostat is dying. You can replace it for under a fiver (IF you can get the bolts out in one piece). Also check that the radiator fan is working by shorting out the thermostatic switch on the radiator with the ignition on. If it doesn't spin then sommat is up with it.

Also check that the thermostatic switch functions correctly too, it should switch the radiator fan on at about 3/4's

Hope some of that helps

Dan

[John]

I had the fan shorted and running continuously and it was still overheating, running at just into the yellow, just over 3/4.
I tried to remove the housing last night and snapped two bolts fwith the top of the housing but still couldn't budge the housing it's solid with corrosion between the bolts, any ideas?

[John]

I had the fan shorted and running continuously and it was still overheating, running at just into the yellow, just over 3/4.
I tried to remove the housing last night and snapped two bolts fwith the top of the housing but still couldn't budge the housing it's solid with corrosion between the bolts, any ideas?

[E_T_V]

That is a VERY common problem. There are a number of options which include taking a very big hammer or saw to it. The thermostat housing that is! And getting a replacement housing. if you are lucky you can prize the thermostat housing off in one piece but often they are so badly corroded that you simply have to resort to destroying it (carefully) to get it off.

With the fan running continuously was there hot air being blown out of the radiator? If it was cold air .i.e., no hot water getting into the radiator then the thermostat is definatly the first suspect.
If the radiator is hot, is it hot all over or is it cold in places indicating a blocked radiator?

Also worth a check is that the water pump is working correctly and the fan belt is not slipping.

While you are trying to get the thermostat housing off just check that the temperature gauge sender is working too. it unscrews from the block and I think the haynes manual gives some reference resistances at certain temperatures.

When you replace the thermostat housing bolts use LOTS of grease to avoid the same problem next time.

[John]

The rad was unevenly hot the first time I tried and the next time it was hot all over. How can I check the water pump?
I will try and flush everything this weekend, what's the best method?
Thanks

[SimonR]

Hi there,

This is what I do: Undo the bottom radiator hose and empty the coolant into a bucket (or large saucepan!) open the expansion tank and with a hose flush the system until it runs through clear. Then remove the radiator, clean and debris from it and flush it out in both directions.

Remove both heather matrix pipes at the non-heater matrix end (because the heater matrix itself seems rather fragile) then flush it in both directions until it runs through clear.

You may well be surprised how much cack comes out of the rad and heater matrix...

[MaestroMatt]

It sounds to me like there is going to be a lot of crud in there. F153's advice is good; you must take out the radiator to flush it in both directions and flushing the heater matrix is a must. Have you used Radweld or similar lately? That can clog up the system something chronic.

It could also be that your temperature sender is up the creek and that the cooling system itself is working perfectly...

[Mat_C]

If this happend all of a sudden, it could well be the fuel ECU. A common failure.

[E_T_V]

Fuel ECU?? on a 1.3? Mine must be missing something then :D

[Mat_C]

Ok then - the SU auto choke control box :) . Assuming of course there is an auto-choke fitted.

It intercepts the temp sensor and temp gauge.

[e692wtt]

And is easily bypassed, but you will need to convert the choke to maunal operation if it hasn't already been converted.;)

[John]

It is Auto choke so that's something else to think about, thanks.
I haven't used rsdweld on this car.

[John]

It was the temperature sensor, I switched on without stating the engine and the temperature went straight up, should have tried that first! Anyway a new sensor and it seems OK, haven't run it yet but I think it will be OK. Thanks everyone for advice.