hazardpro
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| posted on 19/9/16 at 09:25 PM |
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Fan switch
Anyone else have a manual switch for there fan?
Just purchased a MK Indy and it has a bit of a weird fan setup (to me anyway)....
Basically the fan is controlled by a switch under the dashboard. So you have to remember to switch it on before you drive anywhere.... then if you
park up you have to leave the fan on and remember to go out 5mins later to switch it off :/
Anyone run there fans like that? Surely it should all be controlled automatically like on a car?
Doug
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adithorp
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| posted on 19/9/16 at 10:11 PM |
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Mine is switched by the ECU but I also have a manual override.
Why do you switch it on all the time and leave it on 5 mins after stopping? It shouldn't need to be running under normal driving. Usually
it'd only run if the temps start to rise too high; Like in standing traffic.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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SteveRST
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| posted on 19/9/16 at 10:22 PM |
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Thermostat switch on my rad fan has never worked. Just have to remember to manually switch it on if sitting in traffic. I'm kinda used to it
now.
Certainly don't need to switch it on under normal driving or after driving - why would you?
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hazardpro
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| posted on 19/9/16 at 10:24 PM |
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quote:
Originally posted by adithorp
Mine is switched by the ECU but I also have a manual override.
Why do you switch it on all the time and leave it on 5 mins after stopping? It shouldn't need to be running under normal driving. Usually
it'd only run if the temps start to rise too high; Like in standing traffic.
Hi thanks for the reply - ah ok guess that would make more sense. I was told by the previous owner to switch it on each time and leave it running a
short while after a run.
Guess it made sense at the time (I often here my day car fan running when I park the car up).
so the switch is used more for a 'im in traffic and things a heating up'? - but then if that is the case surely the fan would come on
automatically?
I cant think why the need to manually turn the fan on would occur (unless the fan thermostat switch broke or wasn't working)?
Doug
[Edited on 19/9/16 by hazardpro]
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hazardpro
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| posted on 19/9/16 at 10:27 PM |
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So in short I don't need to worry about turning it on or leaving it on after driving the car (unless I notice the water temp gauge creeping
up?
PS Seems to sit at around 80-85 deg under normal running conditions (but of course that is with the fan running all g
the time).....
Doug
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LBMEFM
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| posted on 20/9/16 at 05:26 AM |
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Most MK Indy's use a VW Polo rad which has a thermostatic valve fitting in the top section. If one has not been fitted it's quite easy to
remove the blanking plate plate screw one in, new or used, and wire in via a relay to the fan and the problem is solved.The feed can be either
controlled via the ignition or battery if you want the fan to continue to run to bring the temperature down after you have parked up.
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hazardpro
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| posted on 20/9/16 at 07:17 AM |
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quote:
Originally posted by LBMEFM
Most MK Indy's use a VW Polo rad which has a thermostatic valve fitting in the top section. If one has not been fitted it's quite easy to
remove the blanking plate plate screw one in, new or used, and wire in via a relay to the fan and the problem is solved.The feed can be either
controlled via the ignition or battery if you want the fan to continue to run to bring the temperature down after you have parked up.
Perfect thank you. I'll check it tonight. 
Doug
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owelly
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| posted on 20/9/16 at 07:45 AM |
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As a warning and override for my override (!) I have one of these fitted to the cylinder head near the water outlet!!
http://uk.rs-online.com/web/p/thermostats/0331562/
If my thermo switch for my fan fails, and I don't notice the temp gauge rising, this pings a warning lamp and switches the fan relay. If
it's the relay that's failed, I still have the warning lamp.
During normal running, I have a thermo switch fitted to the radiator as well as an adjustable one fitted to the top hose.
http://www.ppcmag.co.uk
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JMW
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| posted on 20/9/16 at 08:33 AM |
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quote:
Originally posted by hazardpro
quote:
Originally posted by LBMEFM
Most MK Indy's use a VW Polo rad which has a thermostatic valve fitting in the top section. If one has not been fitted it's quite easy to
remove the blanking plate plate screw one in, new or used, and wire in via a relay to the fan and the problem is solved.The feed can be either
controlled via the ignition or battery if you want the fan to continue to run to bring the temperature down after you have parked up.
Perfect thank you. I'll check it tonight.
Doug
It's actually about 1/3rd or 2/3rds the way down the side tube, (it depends which way up you have the polo radiator mounted).
To my mind, and hey what do I know, this is not that suitable a position for our cars.
My view is we need to monitor and respond to the highest coolant temperature not a partially cooled one, therefore the top hose location is a better
place.
I'm sure VW have their reasons for putting it where it is though.
Oh, also I've never thought running on the fan after switch-off is that beneficial unless you also have an electric water pump running
concurrently. All I reckon it will do without circulation is to cool the water in the radiator not the engine. OK then there will be a quantity of
cooler water available on next switch on, but I don't think it cools the engine after switch off. Unless there is some thermosyphon effect going
on I suppose - does anyone know?
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hazardpro
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| posted on 20/9/16 at 09:49 AM |
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Great info guys thanks!
owelly - any change of a idiots guide to installing the thermo switch? Sounds like a great idea....
I just spoke to the mech. that used to work on the car (really nice guy) he confirmed 'the fan will come on on its own its own via the ECU. The
switch is there to help keep cooling during fast road use, track racing, or around town during slow traffic'
I still don't understand why you would need a switch though (unless the thermostat failed) lol... If "the fan will come on on its own via
the ECU" when it gets to a certain temp...then you would not need to switch it on (because it would surely already be ON)...
Maybe i'm over thinking things LOL
Doug
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SteveRST
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| posted on 20/9/16 at 10:02 AM |
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Sounds like it's best to keep an eye on it and check that it does turn on/off when it should. If all is working then I guess you can kinda
forget about the switch - it's useful to have as a backup in case the ECU switching fails for any reason.
So you're on a Megasquirt ECU yeah? If you download the TunerStudio software and have the lead to connect ECU to laptop, then you can connect to
the ECU and see/change what temperature the ECU is set to turn the fan on/off. Not something you need to do by any means, but it's good to know
you can change all these settings yourself.
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hazardpro
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| posted on 20/9/16 at 10:08 AM |
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quote:
Originally posted by SteveRST
Sounds like it's best to keep an eye on it and check that it does turn on/off when it should. If all is working then I guess you can kinda
forget about the switch - it's useful to have as a backup in case the ECU switching fails for any reason.
So you're on a Megasquirt ECU yeah? If you download the TunerStudio software and have the lead to connect ECU to laptop, then you can connect to
the ECU and see/change what temperature the ECU is set to turn the fan on/off. Not something you need to do by any means, but it's good to know
you can change all these settings yourself.
That is good to know (although I have zero experience with ECUs so may be a little nervous (not wanting to mess anything up!) - guess I need to check
it in order to know it comes on / off when it should.
I might try a little drive around without the fan on and see what temp the car runs at and also if the fan comes on at all.
PS 'Megasquirt ECU' I believe so as there is a receipt for one in all the paperwork...
Doug
[Edited on 20/9/16 by hazardpro]
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JMW
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| posted on 20/9/16 at 11:13 AM |
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I'm not sure what a fan gives you once you are moving though.
In stationary traffic or after a blat, yes, but over say 30mph the fan is superfluous surely.
Then the issue is getting the hot air out from the back of the radiator.
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02GF74
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| posted on 20/9/16 at 04:46 PM |
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quote:
Originally posted by JMW
Oh, also I've never thought running on the fan after switch-off is that beneficial unless you also have an electric water pump running
concurrently. All I reckon it will do without circulation is to cool the water in the radiator not the engine. OK then there will be a quantity of
cooler water available on next switch on, but I don't think it cools the engine after switch off. Unless there is some thermosyphon effect going
on I suppose - does anyone know?
Yes, there will be some water circlatng, hot water enters top of radiator and when it becomes cooler it becomes denser hence it wants to sink towards
bottom of radiator. This cause water to flow throght the system as long as thermostat is open. In fact the very first automobiles usef this system
ad they did not have waterpumps.
The water round cylinders will heat up as it no longer circulates at the same rate so this is likely to open the thermostat a bit.
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