Hey fellow brickers

Please excuse if this is a really newbie question but exactly how does one install a manual switch for the cooling fan to come on? I have a K100RS

I have a bit of experience in mechanical wrenching but electrics are a bit of a mystery to me

Any easy to read diagrams or tips would  be greatly appreciated 

Cheers
Gary

Connect a switch between terminal 15 green/brown wire and terminal A2 violet/yellow wire on the temperature switching unit.

Thanks Rick

As I said I am easily confused by electrics............................

Please excuse me if this is an obvious/stupid question.  Why is a manual switch needed?

hi brickrider2

Not really needed at this stage - I was just inquiring about the switch as here in Australia , particularly in the outback areas, it can get over 42deg C in summer.

I was considering a round Australia sometime in the future and I thought a manual switch would be of some help reducing the heat etc etc

Where I live in Tasmania is the most southern state and as such there is no need - its nice to have the warmth from the motor

cheers
gary

brickrider2 wrote:Please excuse me if this is an obvious/stupid question.  Why is a manual switch needed?

Theoretically, it shouldn't be needed.

When I bought my bike the fan motor was fried. I put in a manual switch while I had it apart so I could check that it was still operating, rather than let it get gunked up bearings without me being aware of it, and getting fried again.
It could also be used as a pre-emptive strike to slow the temperature getting to normal fan trigger temp. Could be handy if I were riding today at high 30s temps. Not strictly a 'need', though.

Bill

Yep around 38ish here at present, a mild westerly fanning the fire across the valley floor, Good to see the Summer heat start to dissipate hey.

I fitted a fan over ride switch to both my LTs - not because we get anything like those kind of temperatures in the UK, but it doesn't take much for the fan to start kicking in when caught in slow moving city traffic and I have had problems in the past where the fan didn't kick in when it needed to and I suffered a boil over.

Just a thought though, particularly for those riding regularly in high ambient temperatures, is the fan motor continuously rated? By that I mean, is it designed to run continuously for long periods of time? I have noted from previous fan posts that many fan fails are associated with the plastic melting in the vicinity of the brushes - is this due to too many start stop cycles (with the fan frequently cutting in and out) or is it due to prolonged running (switched on and stays on). Depending on the answer, a fan over ride could be friend or foe. As I understand it, and as explained by Duck on a recent thermostat question post, the engine gets all the cooling it needs due to the air flow over the radiator while moving at a decent speed (the necessary speed is not that high either, in my experience). The fan just provides the air flow when the bike speed is very low and/or the temperature is high.

And if you want to know what you're doing when you install the switch:

Grn/Brn comes from the #7 radiator fuse

Vio/Yel is 12V+ power to the fan

Born Again Eccentric wrote:
Just a thought though, particularly for those riding regularly in high ambient temperatures, is the fan motor continuously rated? By that I mean, is it designed to run continuously for long periods of time? I have noted from previous fan posts that many fan fails are associated with the plastic melting in the vicinity of the brushes - is this due to too many start stop cycles (with the fan frequently cutting in and out) or is it due to prolonged running (switched on and stays on). 

Melted plastic brush mounts was the obvious problem with my fried fan, but in addition the bearings were not allowing rotation.
While I have no proof that this was the reason, a non-rotating armature means that the significantly higher current required briefly to start an electric motor, (normally reducing to a fraction of that when it is running,) would be the constant current level. The heat induced by that, combined with no airflow cooling from the fan would melt the brush mounts.
Based on that theory, I run mine from the switch occasionally to keep the bearings free. It hasn't happened yet, but if I hear the fan running more slowly than usual I will lubricate the bearings.

I don't think it is due to stop starting or prolonged running. I would be very surprised if the motor was not rated for continuous running.

Bill

The fan motor is rated for a continuous duty cycle. It's not under a very large load so the size of the motor is adequate. What causes the burnt brushes is stalling due to bearing seizure, as mentioned above.

I think the only reason you'd want a fan switch is to be able to switch it on in stop/go/slow traffic and probably a good idea to install an LED to remind you its on. I would imagine the bearings and brushes would wear out much quicker if left on needlessly for long periods.

In high ambient temps, my feeling is that the fan won't provide any more air movement than you'd get from travelling at speed. Just because the fan may cut in while you're travelling along doesn't mean you're getting extra air movement and extra cooling. When the force of air from travelling at speed (i'm guessing 40 or 50 klm) exceeds the amount of air the fan can move, the fan becomes redundant whether it switches on or not.
If the fan comes on while you're travelling at speed then it could mean a couple of things....
 - The ambient air temp is really high and the radiator cooling is not as efficient.
 - Your engine is overheating possibly due to running lean (air mixture/leaks etc), valve clearances etc. Oil plays a big part in cooling the engine as well. Old oil or a clogged filter will hinder oil cooling.

I've been seriously considering looking at fitting an oil cooler this winter. Summer temps seem to be getting hotter and hotter here in Oz lately.

It wouldn't surprise me to learn the temps are rising, Kap'in.  The scientific community has been sounding the alarm for some time. Locally, our hottest part of the year is August when we often see a number of days that exceed 100 degrees f. Despite being developed in a rather cool climate, I think BMW did a good job sizing the K-bike's cooling system in general.  Okay, the fan motor must have been the idea of the bean counters, but....
With my after market Spal fan in stop and go traffic, the needle of the thermometer begins to drop within seconds of the fan cycling on.  It's a welcome sight to see on a hot day!  

Thanks everyone for the tips and advice

fantastic to have discussions like these on forums - I am always grateful for any advice I can get 

If anyone is coming to Tassie anytime just let me know and a warm welcome will be definitely in order


cheers
gary

Hey Viper, there's a gathering in the making in April....don't think I can get to Tassie this time around, but if you could get north....it'd be a great chance to meet some of the krew from home and away.

Thanks born again eccentric

Can you give me some details just in case I can get away for a few days???


cheers
gary

Northern Visitor inbound - Sydney:16 - 22 Apr 16

Gary, If you view the Latest Topics on the Portal tab you'll see ALL posts in order as they are posted to the forum... easy.
The Forum tab categorises posts and you then you need to look around to find new posts in each category... easy to miss something.

If you make it to the mainland with your K let us know.... any excuse for a meet-up and ride.
Maybe you could pencil in next year's Snowy Mountains Run.

Cheers

Thanks Kaptain   I will have a look   


cheers
Gary

Personally, I run a manual fan switch on mine because the computer stopped sending ground signal to turn on the fan at the appropriate temperature.  I like the control, really.  And, of course, since it's a K engine, even on the coldest days, you feel the heat and wonder why its so hot all of a sudden as soon as the heat gauge gets to the half way mark (aka, before anything bad is even close to happening).

yep another manual switch user here

works a treat

as I said one time ...no way am I heading off into the hills without ensuring that thing is working properly ...or even to work ....grin

recon the exercise keeps it moving all proper like ....grin

While people are thinking about our radiator fans can I pose a question?

Has anyone ever set up a Go Pro or similar movie camera to video the fan movement when riding? I am curious to know at what road speed does the air flow spin the fan blade (if at all) when the fan is not powered.

The reason for this curiosity is that I have heard a number of people state that the reason for a manual switch is to force some fan movement every now and then to help make sure the bearings (bushes) in the fan motor don't seize up from lack of movement.

Just thinking out loud!

Cheers

In this heat my fan is getting plenty of exercise Gaz 
I had a look today to see where I could fix the sport camera to get a clear shot of the fan but I'm thinking it may be too hot for it so I'm going to have a go at rigging the end of the borescope in there tomorrow and run it back to my tablet in the pannier.

That's a good idea Kaptain. Hope we can learn something from this.

Thanks

gaz ... id have a guess that little movement til up around the 40 kph mark

nature is an amazing thing .. and some good engineering science has let us appreciate riding things that would normally get super hot ..real quick

but to the question at hand ....old gerty had a near seized fan ..(well I could turn it ...if I used a stick ) .and no there was no rotation at speed on this one, just not enough torque was achieved with the air gap between the blades.....just to lossy ...this could be desirable

consider the fan at riding speed ...even if its rotating ...it is acting as a brake rather than an enhancement ...to air passing through the radiator ...

but for me id much rather know the fan is working before I go up that hill, that starts  ...about 70 ks away ...and no phone reception at all ....and know I should get home before dark ...not sitting on the side of the road waiting for her to cool down and furry grasshoppers about to take over the roads

idle at start ...switch on ...it works ...go for a ride ....  if it doesn't ... roll back in the awning and cover on .

Kaptain Holister wrote:In this heat my fan is getting plenty of exercise Gaz 
I had a look today to see where I could fix the sport camera to get a clear shot of the fan but I'm thinking it may be too hot for it so I'm going to have a go at rigging the end of the borescope in there tomorrow and run it back to my tablet in the pannier.

The video is not worth posting so I'll just report. The fan did not move much at all. At around 70kph the blades were moving a few cm and then stop. Checking my fan after with a finger I find it doesn't spin freely, so quite possibly the bearings are dry/gummed up/wearing out. I got the impression that it wanted to spin so I'd say a newish fan would and probably at a reasonably low speed.
Cheers

Thanks for the feedback Kaptain.

From memory when I replaced the fan motor on my K75 those little motors only have a bronze bush rather than a rolling element bearing so next time you have a chance to get at it a good flush around those bushes with WD40 or similar might free it up nicely for you.

Cheers

RicK G wrote:Connect a switch between terminal 15 green/brown wire and terminal A2 violet/yellow wire on the temperature switching unit.

Hello brick colleagues,

To revive a bit this topic...

Could this be done on K 1100, K 100 RS 16 valve and K 1 models too? As 16 valve models do not have temperature switch/relay (BMW Part No 61 31 1 459 009).

AND:

Did someone try installing an adjustable coolant temperature sensor - which you could adjust to kick the fan on at the lower temperature than the standard 103 deg. C? If yes - where and how to get that sensor?

ffbikersa wrote:Could this be done on K 1100, K 100 RS 16 valve and K 1 models too? As 16 valve models do not have temperature switch/relay (BMW Part No 61 31 1 459 009).

Yes, it could be done.  You're correct in observing that the 16V and later K1100 don't have a temperature module like the 8V; the ECU is responsible for activating the fan.  One way to accomplish a manual override is to have the switch in parallel with the fan relay contacts. For the K1100, that is between Green/Brown (+12V) and Violet/Yellow (Fan +ve).

ffbikersa wrote:Did someone try installing an adjustable coolant temperature sensor - which you could adjust to kick the fan on at the lower temperature than the standard 103 deg. C? If yes - where and how to get that sensor?

It should be possible.  Select a temperature controlled relay that has an adjustable set point lower than the K1100's ECU setting and wire the contacts of the temperature controlled relay in parallel with the fan relay contacts, just as you might do with the manual override switch.  The tricky part will be determining where to locate the temperature controlled relay's sensor so that it's measuring a relevant engine temperature.

4V bike fan switch: Have the switch ground the blue/yellow wire to the fan relay to turn the fan on.  (That's what the Motronic does from Pin 2 to turn the fan on.) That's how I do it.

robmack wrote:

ffbikersa wrote:Could this be done on K 1100, K 100 RS 16 valve and K 1 models too? As 16 valve models do not have temperature switch/relay (BMW Part No 61 31 1 459 009).

Yes, it could be done.  You're correct in observing that the 16V and later K1100 don't have a temperature module like the 8V; the ECU is responsible for activating the fan.  One way to accomplish a manual override is to have the switch in parallel with the fan relay contacts. For the K1100, that is between Green/Brown (+12V) and Violet/Yellow (Fan +ve).

ffbikersa wrote:Did someone try installing an adjustable coolant temperature sensor - which you could adjust to kick the fan on at the lower temperature than the standard 103 deg. C? If yes - where and how to get that sensor?

It should be possible.  Select a temperature controlled relay that has an adjustable set point lower than the K1100's ECU setting and wire the contacts of the temperature controlled relay in parallel with the fan relay contacts, just as you might do with the manual override switch.  The tricky part will be determining where to locate the temperature controlled relay's sensor so that it's measuring a relevant engine temperature.

Thanks - that's why I asked if someone knows where to get the sensor (I thought there may be one which can be screwed in the same hole where is BMW's original one?

duck wrote:4V bike fan switch: Have the switch ground the blue/yellow wire to the fan relay to turn the fan on.  (That's what the Motronic does from Pin 2 to turn the fan on.) That's how I do it.

Thanks - but this is a bit Chinese for me, I am not well versed in the bike electrics (can read the scheme, though). Could you please clarify a bit simpler where to connect the switch?

There's a screw that holds the relay connectors to the relay box. Remove that so you can pull the relays up and have access to their wires. You will see blue wire with a yellow stripe that goes into the fan relay. Tap one wire from the switch into that wire. You can use a Scotchlok connector to do that but I prefer to use a Posi-Tap.

Connect the other wire from the switch to ground. There's a main ground connection to the frame under the tank. It's the bolt with all of the brown wires going to it.

ffbikersa wrote:Could you please clarify a bit simpler where to connect the switch?

Duck was indicating to you the location on the bike where you will find the relay to which you need to connect your switch.  The diagram is a location diagram of the relay box.  The relay of interest is the one in the top right corner labelled "Radiator Fan".  It's there you will find the Blue/Yellow wire; also the Green/Brown wire and the Violet/Yellow wire..

ffbikersa wrote:Thanks - that's why I asked if someone knows where to get the sensor (I thought there may be one which can be screwed in the same hole where is BMW's original one?

There is no sensor that replaces the BMW one, to my knowledge. The BMW sensor is an NTC resistor and is used to tell the Motronic the colant temperature. The ECU makes a decision to turn on the fan based on coolant temperature.  You don't want to fool around with that sensor.

What you purchase will be a thermostat switch, similar to what I picture below:

robmack wrote:

ffbikersa wrote:Could you please clarify a bit simpler where to connect the switch?

Duck was indicating to you the location on the bike where you will find the relay to which you need to connect your switch.  The diagram is a location diagram of the relay box.  The relay of interest is the one in the top right corner labelled "Radiator Fan".  It's there you will find the Blue/Yellow wire; also the Green/Brown wire and the Violet/Yellow wire..

ffbikersa wrote:Thanks - that's why I asked if someone knows where to get the sensor (I thought there may be one which can be screwed in the same hole where is BMW's original one?

There is no sensor that replaces the BMW one, to my knowledge. The BMW sensor is an NTC resistor and is used to tell the Motronic the colant temperature.  The ECU makes a decision to turn on the fan based on coolant temperature.  You don't want to fool around with that sensor.

What you purchase will be a thermostat switch, similar to what I picture below:

Great! As yoou wrote b4, "The tricky part will be determining where to locate the temperature controlled relay's sensor so that it's measuring a relevant engine temperature" - well, the relevant is coolant temperature. These switches have a metal casing, metals transmit the heat well. Fix the switch against the radiator back side, towards the engine, and apply some heat transmiting paste - the same used between coolers and computer chips - between the switch and radiator?

I think you should stop and wonder why you want to do this, add this thermostat.

The temp sensor on the K-bike is designed by professional engineers to operate in conjunction with the ECU according to the demands of the engine. The engine temperature can't be too cold otherwise performance and fuel economy are impacted.

Riders add a manual switch to occasionally override the temperature control function of the ECU when they know the bike will potentially overheat - stuck in stop-go traffic on a very hot day. That way they can get a jump on the rising temperature and mitigate a potential problem. Your thermostat will cycle the fan sooner than designed, in all weather, causing coolant temperatures to drop and therefore engine temperatures to decline. IMO it's not a great idea.

robmack wrote:I think you should stop and wonder why you want to do this, add this thermostat.

The temp sensor on the K-bike is designed by professional engineers to operate in conjunction with the ECU according to the demands of the engine.  The engine temperature can't be too cold otherwise performance and fuel economy are impacted.  

Riders add a manual switch to occasionally override the temperature control function of the ECU when they know the bike will potentially overheat - stuck in stop-go traffic on a very hot day.  That way they can get a jump on the rising temperature and mitigate a potential problem.  Your thermostat will cycle the fan sooner than designed, in all weather, causing coolant temperatures to drop and therefore engine temperatures to decline.  IMO it's not a great idea.

The thermostat doesn't cycle the fan, the Motronic does.

I agree with the "it was designed to run at "X" temperature" when it comes to replacing the thermostat with a cooler one but the factory thermostat is designed to operate at 85 degrees (185F) and the fan kicks in at 105 degrees (221F).

When the bike is cruising along the thermostat usually controls the heat and keeps the bike running at around 85 degrees so if you add an additional fan switch that is set to kick in at 85 or above then the bike would still be running within the design temperature range but the fan might just kick in more often when slowed or stopped.

duck wrote:

robmack wrote:I think you should stop and wonder why you want to do this, add this thermostat.

I agree with the "it was designed to run at "X" temperature" when it comes to replacing the thermostat with a cooler one but the factory thermostat is designed to operate at 85 degrees (185F) and the fan kicks in at 105 degrees (221F).

When the bike is cruising along the thermostat usually controls the heat and keeps the bike running at around 85 degrees so if you add an additional fan switch that is set to kick in at 85 or above then the bike would still be running within the design temperature range but the fan might just kick in more often when slowed or stopped.

And you end up "stuck in stop-go traffic on a very hot day" watching the temperature meter needle going into red, grinding your teeth will the fan kick at 105 degrees or not... That is why I would want it to have it, to activate the fan just slightly before, at, say 95 degrees. And then if I see it's still does not happen, I could still use the manual switch and later check what was wrong. Simply, it would give  me more peace of mind.

Correct me if I am wrong but even if the fan was wired to run all the time wouldn't the thermostat still regulate engine coolant temperature ?

caveman wrote:Correct me if I am wrong but even if the fan was wired to run all the time wouldn't the thermostat still regulate engine coolant temperature ?

Once the thermostat routes coolant through the radiator, the only other means of cooling the engine are swift forward motion, operation of the fan and riding further away from the equator, or shutting it off.

duck wrote:4V bike fan switch: Have the switch ground the blue/yellow wire to the fan relay to turn the fan on.  (That's what the Motronic does from Pin 2 to turn the fan on.) That's how I do it.

I just noticed on this image 94+ K 1100 - by the chassis number, my K 1100 RS was produced in 03/1993 - so it's the first series, that still had e.g. ABS of the 1st generation. Is it of any importance for attaching the manual fan switch? Or I can still do it in the described way?

The changes in electrcs etc. occurred after 06/1993

For an early ABS I bike:



And you'll still want the switch to ground the blue/yellow wire to the fan relay. (Pin 16 from the early Motronic.)

Perfect, many thanks!