h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

My understanding of the cooling system in a car is that works something like this:

1) liquid in the radiator is pumped around the hot bits of the engine - that's most of it I presume - and is returned back to the radiator.
2) The now hot returning liquid runs through the fine grill of the radiator where the air-flow from the motion of the car cools it.
3) When a car is stationary with the engine running, there is unsufficient air-flow through the radiator for it to its job effectively, and hence the overall temperature of the system rises.
4) This is a bad thing.
5) In response to the rising temprature an auxilliary fan is started up, which blasts air through the radiator to replicate the air-flow equivalent to that of tonking down the M1 at 90mph.
6) The application of this fan reduces the system temperature, and all is right with the world.

I think my fan is bust.

The car doesn't overheat at all ever whilst it is in motion. But give it 10 minutes in congested traffic and the temperature guage starts heading north. Give it another 10 minutes and a little red (actually quite big red ) light comes on and says 'Stop'.

At no time during this process it static traffic do I hear a funny whirring sound coming from under the bonnet, other than the usual funny whirring sound which I have always assumed is the engine.

Have you checked the fan belts?

Sounds plausible to me. What do you drive?

One other thing that it might be (note, I am not a mechanic, I just know a bit about cars (USian ones as well as some Swedish and Japanese ones)) is that your water pump might be out. Sometimes your motor will have a wonky water pump that only works when there is high pressure in the water system.

Fix the problem quickly as heat is the most damaging part of internal combustion.

Right well first thing first I would pop the bonnet outside of your gaffe whilst the car is idling and actually have a look to see if this is happening.

Check the sides of the radiator particularly at the bottom to see if the is any obvious water leakeage, similarly check the hoses to see if water is comeing out of them. Be carfull though they might well be hot to touch.

Unless you have a sealed system - check there is sufficient fluid in your radiator.

Some fans run all of the time, although that's probably on older models before they invented electricity to run them as and when.

Could also be a head gasket gone, if those sorts of things exist anymore.

PS Have changed subject as the 'Dummies' guys have redhot lawyers who search the net for breaches. I'd ask the mods to star out dummies in the first post or something if I were you, as it's appearing on conversations lists all over the place.

Thank you all for your input.

I remain convinced that it is the fan that isn't working. I had the bonnet up this lunchtime and ran the car in idle. The temperature started to rise just as expected after a few minutes, and there was no sound of any activity coming from the fan.

Fixing that I think is going to be beyond my abilities. So it's off to the garage with it some time soon. I'll probably lump it in with the MOT next month.

Mina, thanks for the heads up about the Dummies' lawyers. I'll ask the Mods to mod

If you get worried about the engine overheating in stationary traffic before you get this problem fixed, don't forget that you can always lower the temperature by turning on the heater. Not the most comfortable thing to do in hot weather, but it works.

The Mods have replied that they aren't gping to edit the fist post's title, as it doesn't in their opinion break house rules

Except as soon as I saw my last post come up in the thread, I saw that they *had* edited the title

Mods can't edit entire threads. In cases like this, drop us a line to our h2g2.feedback address at bbc.co.uk and we'll do it manually.

That was quick then!


Geggs

And now I see a follow on reply from the Mods e-mail from h2g2.feedback that says:

"The Moderators can't actually edit entire threads - only the in-house
staff can. We'll sort this out for you now "

Job done then

Multiple simposting and discussion of editorial ins and outs and stuff

Lovely job! Personally I wasn't bothered about the entire thread, but thought if they did the first one at least it would look better on conversation lists.

Can't you see the fan? I think that I prefer the old cars. You could look at them and see which bit wasn't moving/was leaking/had completely vanished.

or was never actually there in the first place, and hence always had been some thing wrong with the car....

Excuse me for being more-than-averagely thick, but who the heck are the 'Dummies' people?

http://www.dummies.com/WileyCDA/

Getting back to the original question...

Have a look towards the top of the radiator - there should be a couple of electrical wires going into a thermostat - screwed into the radiator.

That thermostat turns the fan on and off - and you might just be lucky, if the electrical contacts have corroded, the thermostat won't be working and the fan won't turn itself on.

Pull off the plug and look at the contacts - if they're green and yukky, clean them off with a wire brush and plug it back in again.

It might be as simple as that!