Radiator Fan 172 Cup

[Ex-User (54566)]

Can anyone tell me if it's supposed to stay on after the engine is switched off? I just went out to the shops and then stopped for approx 45 minutes. When I got back in the water temperature was still sitting in the normal area and hadn't cooled off at all. Just to be sure I checked when I got home and the fan was not spinning, should it be?

Cheers

 

[Soot1e]

Yes they can stay on for a few mins after switching off when the engine is hot, but 45mins is a long time. Could be other problems which is making the water temperature too hot.

 

[Ex-User (54566)]

Hmm the engine was definitely hot but I don't think the water temperature was too high, the gauge was in the normal position when driving. I know the fan worked two weeks ago because I heard it come on when I was out of the car and it was idling but since then I've only driven it a couple of short journeys. Should it run every time the car stops or just after a really long journey, because I only did 30 miles today.

 

[Ex-User (54566)]

Anyone else know?

 

[Soot1e]

If your temp. guage says normal then I would assume the engine is about the right temperature, so it looks like the Rad sensor is faulty and just switching on and off randomly. To test it unplug the wiring plug from the rad sensor and the fan should stop running.

 

[Ex-User (54566)]

So the fan should run all the time when the engine is running? Because I'm pretty sure it doesn't!

Might be a silly question but does any of this mean it will fail its MOT? It runs out in exactly 1 month.

 

[Twisty]

I just read this thread and think there may have been some confusion.

The fan is controlled by a temperature sensor which turns it on when the coolent goes above a certain temperature.
The fan does work after the ignition is turned off. This is the main reason for disconnecting the battery when working on the engine - so the fan does not cut off fingers. However the fan does not normally remain on for more than 5 mins as this is all that is required to reduce the temperature of the radiator.

There are more detailed tests you can do, but I would not worry unless the temp is going into the red without the fan kicking in.

The engine can remain warm after an hour on a warm day - there is a lot of energy stored in all the water etc.

 

[Ex-User (54566)]

Makes me feel a bit better that it can stay hot for up to an hour I suppose. Come to think of it I haven't driven in really hot weather (30 degrees +) at all so I can see why it might no stay on, maybe it just isn't getting hot enough. I'm probably worrying over nothing so unless I see the temperature rocket I'll leave it alone. I know the fan works as I've heard it a couple of times when I've been idling for a few minutes.