Hi all, this may be an issue that has been covered lots of times however I thought I’d be best posting my specific situation to see if I can seek help. 
 

There has been a number of times now where when idling my car for a long period of time (eg sitting in traffic), the car has started to overheat and has forced me to have to turn the engine off. However when at speed this does not happen, presumably because of the increased air flow to the engine.

Twice now, when I have stopped the car and opened the bonnet, there has been steam and hissing from the coolant bottle. After watching for around 10 seconds, I watched the coolant bottle empty itself in a matter of seconds. However both times when I have refilled the coolant, there has been no more leakage at all, as if it only leaks when it overheats. 

I am pretty sure this is a radiator fan issue, however I assumed that this was resolved after I had a coolant leak fixed previously by my local mechanic. 

If anyone is able to help that would be great 🙂

As you say, sounds like the radiator fan isn't coming on.  That's where you should be testing next.  Does it come on with AC?  Does it come on if you unplug the coolant temp sensor?

On 7/6/2024 at 8:05 PM, TomsFocus said:

As you say, sounds like the radiator fan isn't coming on.  That's where you should be testing next.  Does it come on with AC?  Does it come on if you unplug the coolant temp sensor?

I will test this with AC etc. I am not very knowledgeable of the high and low fan speed or if the fan should come on straight away or not. However I did notice there is no fuse in the “cooling fan high speed” slot in the fuse box. I am unsure if the fan is able to operate adequately without?

29 minutes ago, Clg2002 said:

I will test this with AC etc. I am not very knowledgeable of the high and low fan speed or if the fan should come on straight away or not. However I did notice there is no fuse in the “cooling fan high speed” slot in the fuse box. I am unsure if the fan is able to operate adequately without?

No electrical circuit will work with a fuse removed.

However, there are a few different fan setups so it may be that your car doesn't use that circuit for the fan.

If you switch the AC on, the fan should come on immediately regardless of engine coolant temp.

If you unplug the coolant temp sensor, the fan should come on as a failsafe.

Without AC on, if the coolant reaches around 92c, the low speed fan should come on.  If the coolant keeps increasing up to around 98c, then the high speed fan should come on.

Those temps are approximate as it differs depending on engine.  Some of these also only use a single speed fan.

The engine needs to be running for all of the above tests.  But beware the fan can run without engine switched on, so don't put your hands anywhere near the fan blades just in case it starts suddenly.