BMW K bikes (Bricks)

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floyd

floyd
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Howdy Krew


My fan used to come on all the time. 

A few months ago I completely flushed the cooling system several time using a cleaning product. 

I also fitted a nice 3 bar radiator.

Ever since then the fan has not come on. At first I assumed it was a result of the cooling system working a lot better. But it wont turn on even when the bike is left to idle for 10-15 mins.

- The fan will come on fine when I jump the appropriate wire in the relay socket.
- the temp warning light comes on when the appropriate wires are jumped in the relay socket.
- the fan does not come on when the temp sensor wires are jumped
- There is continuity between the temp sensor and the FI computer and the relay socket
- it will not start when I ground the E wire in the relay socket (with the temp sensor unplugged)
- It will not start when I ground the temp sensor wire
- checked resistance at relay socket when hot and cold and got expected readings 

So based on all that, the fan is fine, the wiring is fine, the temp sensor is fine....which leaves the relay. I should have 2 spares but can not find them anywhere. A new one is $160 AUD (F%$k!!!)

Is it possible to test the relay? it looks fine on the inside and the contacts are not fused shut.

Am I missing anything else?¿?¿


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

Inge K.

Inge K.
VIP
VIP
Try to ground "E" with the relay present in the socket, if the fan don't start you need a new relay.
I'm assuming that you have checked that you have power on 9 and ground on 31.


__________________________________________________
Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

Point-Seven-five

Point-Seven-five
Life time member
Life time member
Is there a coil that closes the fan contacts?  Is there continuity through the coil, or is it opened?  I am not familiar with that relay, but those are the first questions that come to my mind having read what has been checked so far.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

floyd

floyd
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Thanks Inge.

No go. looks like ill need a new relay Sad

Anyone got one?


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

robmack

robmack
Life time member
Life time member
You've got nothing to loose by opening the relay and carefully examining the circuit card.  What you are looking for is cracked or cold solder joints.  I had the same problem as you one time on my K100.  I found a cracked joint on the circuit card and, using my soldering iron, I reheated the joint to re-melt the solder.  It brought the relay back to life.  If I remember correctly, the cracked joint was on one of the contact tabs.  Use a powerful light and magnifying glass to be certain you have looked over everything carefully.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

charlie99

charlie99
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get smithys Floyd

then send me yours for examination ????


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OTemperature Relay - Cooling fan not working Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

floyd

floyd
Life time member
Life time member
Thanks Robmac

Examined in the sun with a 30x mag. glass and my untrained eyes cant see anything out of the ordinary.



Cheers Charlie, Ill PM smithy and post you my unit


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

floyd

floyd
Life time member
Life time member
bugger. double bugger in fact.....

It seems that both my relay and temp sensor are buggered. 

smithy was kind enough to post me a known working relay.....

The idle test with the new relay installed resulted in nothing....no fan

I then performed the following test:
_________________________________________________________________________________
earth the wire on pin E as you know. but you need the sensor and relay all connected and place a bridging wire on pin E to earth. Then you need to start the engine, when you press the start button you should here the fan come on.
If fan comes on the problem is with the sensor.
If no fan, the problem is with the relay.
This test needs to be done with the engine running, not just ignition on, or you wont get a result.
_________________________________________________________________________________

with the E pin earthed and the engine running, the fan came on. (It did not come on with the old relay installed, confirming the old one was buggered)

So, the new relay is fine....but my temp sensor is shite.

This is weird because it gives the correct ohm readings at the female relay socket when the engine is hot and cold......


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

floyd

floyd
Life time member
Life time member
Clymer suggests testing the fan/system by disconnecting the temperature sensor plug and jumpering the connectors. With the key on, this, they say, should turn on the fan motor. 




can anyone confirm this is accurate?


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

Inge K.

Inge K.
VIP
VIP
@floyd wrote:So, the new relay is fine....but my temp sensor is shite.

This is weird because it gives the correct ohm readings at the female relay socket when the engine is hot and cold......

This doesn't quite make sense, have you let the engine idle long enough?
The fan should start at ~175 ohm......

What Clymer suggests is far out, what you then do is connecting the fan
relay and Jetronic unit together.
I would guess this have been written a Monday morning, and they have
mistaken the temp sensor for a thermo switch.


__________________________________________________
Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

smithy

smithy
Life time member
Life time member
Floyd if you earth the wire from the sensor that goes to pin E of the relay with the engine running the fan should start, and does as you've mentioned. So that discounts the relay as the problem.
The sensor could be shagged, or may not be making a good earth.
Make sure you get the bike up to operating temperature, then let it idle for a while to see if the fan comes on.
If fan still doesn't come on I would suggest that the sensor is rooted.


__________________________________________________
87 K100rs : Vin 9462 
86 K100rt : Vin 9901
Naked
98 K1100lt: Vin 8044
    

Inge K.

Inge K.
VIP
VIP
I remember that Charlie did have bad ground connection on his sensor some
time back......this will also affect engine running.
But as you say that you read normal values when the engine is hot and cold
is confirming that the ground connection is OK.


__________________________________________________
Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

charlie99

charlie99
VIP
VIP
sounds very confusing Floyd

just as a query ...does the light in the dash - instruments come on when the fan is working ?  if not ..could this be a clue ?


the second thing to check is that the body of the temp sensor  to the main earth point  does not read high ...or anything more than an ohm ....at anytime

third and last thing to ask ...is your thermostat in the radiator working properly ....do you see it cease rising in normal conditions at about 90 odd degrees c ...( talking about the additional instruments temp gauge ) apologies if you don't have one and I forgot .

cheers and good luck



Last edited by charlie99 on Mon Mar 09, 2015 4:48 am; edited 1 time in total


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OTemperature Relay - Cooling fan not working Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

floyd

floyd
Life time member
Life time member
Inge...you are bloody right....as usual! Wink


Earlier, I let it idle for 15 mins - no fan. I didnt want to let it sit idling for longer then that....based on all reports it normally comes on after about 10mins....

simthy suggested I go for a decent ride first to get it up to temp, so I went for a rather spirited ride up and down the Galstone gorge

Yum Yum!  (Google Map)

Then let it idle in the shed....and what do ya know? on comes the fan... Wink

Thanks all!



Last edited by floyd on Mon Mar 09, 2015 5:01 am; edited 1 time in total


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

charlie99

charlie99
VIP
VIP
woohooo !!!


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OTemperature Relay - Cooling fan not working Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

92KK 84WW Olaf

avatar
Life time member
Life time member
Another happy K rider!


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 105,200 miles
1983 K100RS 0011171 Fricka 606 29,495 miles Damn K Pox Its a Bat outta Hell Now 36,188  miles
    

Inge K.

Inge K.
VIP
VIP
Temperature Relay - Cooling fan not working 112350


__________________________________________________
Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

smithy

smithy
Life time member
Life time member
Good result Floyd. Temperature Relay - Cooling fan not working 112350


__________________________________________________
87 K100rs : Vin 9462 
86 K100rt : Vin 9901
Naked
98 K1100lt: Vin 8044
    

Ed

Ed
Life time member
Life time member
good on you Floyd , top result.
nice spot down there on the Berowra waterfront. Did you stop for a coffee or were you pumped to get back and check the sensor.
you should be fine for the Eden ride now.


__________________________________________________
1987 K100RT  Ex- police        
1989 K100LT  Ol' Blue and "Kart" the Kamper trailer.  now KAPUT . 
1993 K1100RS  0194321         Colour #690 Silk Blue  aka " Smurfette"
2018 Kart upgrade.
Temperature Relay - Cooling fan not working 10_x_110
    

floyd

floyd
Life time member
Life time member
groverK wrote:good on you Floyd , top result.
nice spot down there on the Berowra waterfront. Did you stop for a coffee or were you pumped to get back and check the sensor.
you should be fine for the Eden ride now.

Nah the Galstone gorge road is just a bit south of the Berowra waters one. Both stunning though, and the Berowra one has the added adventure of the ferry crossing at the bottom and a cafe or 2, as you say Wink

Its a great loop from where im staying to head east through the Galstone gorge and then come back via Berowra waters. 

Big advantage of the place im 'crashing' at the moment (Dural). There are some great roads right on my door step. The 2 mentioned above, the Old Pacific Hwy, Wisemans Ferry etc etc.

Looking forward to Eden. Have been loving life on the road, and these solid walls and ceiling are starting to give me claustrophobia Wink

Back to the fan though....Great to know its working again....but wow the difference in cooling since I cleaned the system and also fitted the 3 core radiator is remarkable. Earlier, the fan would come on very regularly. Now it seems it takes a lot longer. Although not much testing so far, so we'll see. 

I wonder what killed my relay, as it was working fine, and internally it looks ok to me. Ill send it to Charlie the electro guru kuru for his investigation.


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

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