Well, I think it is...

It was running when we got off the motorway yesterday, air temp wasn't that high, engine temp was fine, and we'd been driving along just fine, I don't understand why the fan would run as we come off the m-way to a roundabout

Could it be the temp sensor, I thought they usually stopped working altogether, not working overtime and being zealous...

Or, something more serious like h/g on it's way But then again, no oil I can see in the water / mayo in the oil / or high engine temps or anything....

Oh, and the fans cut out shortly afterwards, so the cooling is working

Any ideas ???
Thanks

 

Usually when thermostats start sticking open the fans come on very frequently and for very short amounts of time, although if u had just come off the motorway and the stat was open too much i wouldn't of expected the fan to be on.

Could well be the fan switch, they're only bi-metallic strips after all.

What does it do when its left idling? does it cut in way early?

 

Difficult to tell, the temp gauge in the car isn't that accurate... But the fans do cut in.
I am just surprised that they would be running after a long blast on the motorway (and not caning it either which could explain it).

 

Well, first things first you need to sort the gauge in the car out.

Dont forget when you are on the motorway theres a lot of air flow then to suddenly slow down sometimes the temperature does rise for a short amount of time.......

 

It's the std gauge, it works fine, but there's only a tiny amount of movement in it between normal operating temp, and fans cutting in if you see what I mean

 

I could be wrong but standard gauges aren't usually that precise?? You sure the gauge/sender aren't playing up?

 

The gauge and sender appear to work ok, I mean the gauge is low to start with, then rises after a few minutes of driving as it always has in the last 8 years I've owned the car

Normal operating temp is as usual. Unless the sender stops working after a given temperature, all appears ok on that front.

 

I've had a gauge before that would rise to the bottom of the normal temperature on the guage, when the engine was at 50-75% of operating temp, and would then go back down to nothing before the fan cut in.......

Might be worth a quick once over

 

How can I go about checking water temps without making holes in my hoses and fitting aftermarket gauges to the car ?

I suppose I could take a reading off the water temp sender while I am driving, and off the ECU too

 

You can check the gauge by pulling the sender wire off and bridging it to earth, which should show as max. temperature.

And if thats ok, u could try a new sender for the couple of quid they are worth?

The ECU CTS would have different values to the one for the gauge im pretty sure.

 

Greg if i were you i would deal with the root of the problem.................

take the fan switch out of the radiator and place in a pan of boiling water with a thermostat and check the resistance with a MM to see when it tirggers the fans then go from there.

 

Good plan sir

 

Agreed

 

Obviously I meant thermometer and not thermostat in the pan

 

I have to admit i was a at the thermostat bit

Let you off this once, dont let it happen again