Cooling Fan Runs When Car Is Switched Off

[starky5 18]

I have been having over heating problems as my fan wasn't kicking it at all so i have just changed my radiator fan switch. I re-filled the coolant and then left the car running to check if the fan kicked in. Before i changed the switch my temp gauge worked but now it appears it doesn't as it was reading cold when my expansion tank started steaming! And my fan still didn't kick in! So i turned the car off and a couple of mins later as i was about to come here and ask for help my fan kicked in! With the ignition off! is this normal?

 

I'm now worried that the fan is going to kick in when the cars parked up and run the battery flat. Also, any ideas on why my temp gauge now doesn't work? I only touched the radiator fan switch, are they linked?

 

Help!?

 

Thanks

[Anthony 1,003]

Yes, that's normal behaviour for the fan to run on with the ignition off on 205's (other than AC or diesel models)

 

If, like many 205's, your slow speed resistor is knackered/missing, the standard GTi thermoswitch won't turn the fan on high speed until 102 degrees (about 3/4 on the gauge) so you would expect the expansion tank to be bubbling/steaming without a radiator cap on to pressurise the system. Slow speed should come on at 97 degrees (about 2/3 on the gauge)

 

The cooling fan and gauge are completely independant - for the gauge, the likely culprit is a wire come loose. On an Mi16, the senders are on the top and side of the thermostat housing, each with a single spade terminal. The gauge is the shorter of the two, and the warning light is the taller.

[starky5 18]

I had fitted the cap when it was boiling but I'm not sold on how good a seal my cap gives! Once the high speed had kicked in for a while it did drop to slow speed, does this mean my slow speed resistor is ok or does that happen automatically?

 

Where is the slow speed resistor located and it is possible to test it?

 

Thanks for your help so far!

[welshpug 1,679]

if it dropped to a slow speed then its working fine, it should be clipped to the top of the radiator with a metal clip.

 

it may be that the thermostat isn't working properly, which would explain the very hot coolant in the tank but no fan.

[starky5 18]

if it dropped to a slow speed then its working fine, it should be clipped to the top of the radiator with a metal clip.

 

I think this might be what i have zip ties in place down the side of the radiator!

 

My thermostat was new when i put the engine in about 3000 miles ago but was a cheapo jobbie! Can you suggest a reliable supply for them?

[Anthony 1,003]

First and foremost, fix the gauge so you know how hot the engine is - without this, you're guessing.

 

If you're in any doubt as to the condition of the radiator cap, replace it.

 

Otherwise, to me it sounds like the fan is working pretty much as it should - as standard, GTi's do get pretty hot before the fan comes on high speed, and is the reason why I tend to run a lower rated thermoswitch and have the fan come on high speed straight away in my own cars as I'm not happy with how hot they otherwise get in traffic.

[starky5 18]

The gauge is the first on my list, as it was working this morning before i changed the radiator switch I'm guessing i have probably just knocked a wire. With the cap i have had 3 now including the original and they just seem to be a cheap and crap quality, they are the metal type but just look cheap.

 

I did contemplate getting a lower temp switch but thought i would get it working properly first and see how i get one. What thermoswitch are you running for future reference?

[Anthony 1,003]

The purple banded one - low speed 92 degrees, high speed 97 degrees (approximately 5 degrees cooler than the red banded GTi one). If you do a search, I know that Meirion posted the part numbers of that and the other available ones a little while back.

 

As said, mine's modified so that it goes full speed straight away, which means that in reality, the fan comes on a little past half way on the gauge, and turns off again just before half way.

 

Note - don't do this if you're running an 89 degree thermostat, otherwise the fan won't switch off (or atleast, will take a long time to do so)!

[welshpug 1,679]

very valid point there Anthony, the standard stat is 89, so you'd need to swap to an 83 for the lower temp thermoswitch to work properly in conjunction.

[starky5 18]

Right the gauge is now working again (the wire had snapped) and ive just run it up to temp again and this time the fan kicked in and it all stayed at a nice temp. It hit about 2/3 on the gauge then the fan brought it back to just about half, so im guessing the new switch just needed a little time to get working correctly!

 

Thanks for the help.

 

I did look at changing to an 83 stat and lower temp fan switch which will be my next port of call if it still runs a bit hot in traffic

[roccorich 16]

Ive recently fitted the fan switch Ants talking about in mine as my car had an even lower rated one with an 89 thernostat!!!

 

I still have an 89 thermostat so the low speed does come on a bit keen.

 

If you do want to change to this one ill post it to you for a fiver. Half what paid for it about 3 weeks ago.

 

Its an intermotor on and I can send you a copy of the ebay invoice if you like.

 

Then Ill get the higher temp one for mine.

 

Cheers

 

Rich

[welshpug 1,679]

or just fit an 83 deg stat.

[starky5 18]

The car is running nicely now and doesn't seem to be getting to hot so I'll stick with what I have thanks