Overheating problem

[Galsia]

.

[Enright]

I think you had better change your thermostat - fast!

[Doug]

I dunno if this is related or not but I was in traffic the other day and my temperature gauge went to the max and the radiator fans didn't come on. I had to park up and wait for my engine to cool down before continuing with my journey. Where are the fans located? I couldn't find them. It it a bumper off job?

Thanks for your help...

I agree this problem is likely your thermostat sticking closed!! If so it can overheat your car and blow the head gasket -- when it sticks like this the dash temp gauge sensor does not get the water flowing on it and so sees cooler water than actual . . . be advised start looking into a new t-stat and gasket! Hopefully fixing this will fix the other problem too.

[GeoffSmith]

Wiki help.

[RayD]

I’m sure the above will be right but you’ll still need to know if the fans are working.

Locate the radiator fan thermal switch on the thermostat housing... fasten one end of a length of wire to earth and the other to a fine sewing needle. Stick the needle through the RFTS wire insulation with the ignition on, the fans should start.

This is a good opportunity to find out if the water temperature can be so different either side of a closed thermostat; do they have a bleed hole? and could they do with another one?

Has anyone had a thermostat fail shut?

Galsia, before you sling the old one, boil it in a pan of water to see if and when it opens.

Ray

[tigerdog]

By all means, check the thermostat, but just another thought. The heater valve is normally open until pulled closed by vacuum. A bad valve would let water into the heater core all the time. A loose vacuum hose or stuck-open valve would cause the symptom you describe.

[Doug]

By all means, check the thermostat, but just another thought. The heater valve is normally open until pulled closed by vacuum. A bad valve would let water into the heater core all the time. A loose vacuum hose or stuck-open valve would cause the symptom you describe.

so could be a bad engine t-stat and that brought out symptoms of a bad water heater valve . . . there's some write-up for that valve too.

[RayD]

Hi Galsia,

Use the new gasket, while it might look like cardboard - they used to be cork - it will be designed to swell when it gets wet and make a good seal.

As regards the old one if it opened in the pan it would normally have opened in the car - there is a small possibility it was stuck closed and taking it out has disturbed it.

Ray

[Doug]

it's cheap and simple enough that you should put in the new one and then see how it affects the other footwell symptoms

start looking into that other vacuum actuated valve for the heater pipe too . . .

[RayD]

You still need to know if the fans are working, or if a fuse has blown.

When you get it back together check Tigerdog’s suggestion as to whether the heater is on full time.

As a matter of interest I set my heater to full temperature, the position control to the footwell, the heater fan off, and the roof down during a trip on Sunday and never noticed the heat. So much so, it’s still set like that now.

Ray

Edit...Sorry for repeating your suggestion Doug, I was typing in Word while you were posting.

[Galsia]

.

[Galsia]

.

[RayD]

Galsia,

Try to find if the heat is coming from the heater, and not something else.

If one of the vacuum pipes are off, or leaking it’s usually accompanied by an high tickover. Pull one off... the revs should rise.

Ray

[Galsia]

.

[Doug]

it sounds like your heater valve is stuck open; thus your heater core is helping radiate off the engine heat and keeping the coolant cooler than it should be

time to replace that valve -- there's lots of info on the jag part and others people have used in the Forum here somewhere . . .