Author Topic: Cooling issues and fan not working K1100LT ‘92  (Read 723 times)

Offline Doodaadog

  • Motobrick Curious
  • Posts: 26
Cooling issues and fan not working K1100LT ‘92
« on: July 12, 2018, 05:51:27 AM »
...firstly sorry if this topic has been covered....I have searched and read what I could but am still perplexed...
So have an ongoing saga of recommissioning my K11 which was holed up not running for 8 years...

Seem to have everything working and all fluids renewed.....my problems now alll relate to cooling...
Symptoms: no reading at temp gauge and fan not coming on, resulting in coolant overheat light coming on.

What I’ve tried....
Tested thermostat which opens at the correct temps....
Cleaned contacts on the bottom water sensor (under the water pump).....no difference....
Fans spins freely when moved by hand
Tried to put 12v direct to fan....but does not operate
Checked contacts on relays (all clean)
Fuse is ok

...from what I’ve read the bottom sensor just runs the temp gauge? So that has nothing to do with fan....guessing mine is toast...but don’t know how to test.

So what signals the fan to operate?....is it the sensor on the coolant manifold on the rad?

Could someone help with a test sequence and next steps please?

Regards Greg
  • Lincoln, England
  • K1100LT 92
Ducati Monster 1200s
Montesa 315R
BMW K1100 LT

Offline John Lang

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  • John Lang
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #1 on: July 12, 2018, 06:59:54 AM »
1) Check your fan relay. 2) Search on   test fan   in the Motobrick Workshop. Lots there, including on how to check the fan relay.
  • Ottawa, ON Canada
  • 1987 K75C

Offline Laitch

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Re: Cooling issues and fan not working K1100LT ‘92
« Reply #2 on: July 12, 2018, 07:21:03 AM »
So what signals the fan to operate?....is it the sensor on the coolant manifold on the rad?
It's the sensor in the box depicted in the attached image.
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.

Offline Scott_

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Re: Cooling issues and fan not working K1100LT ‘92
« Reply #3 on: July 12, 2018, 07:46:45 AM »
If you put 12v direct to the fan with correct polarity and it didn't work, you probably need a new one. More often than not, the fans are bad by now. I've had to replace the one on my '95 last year. There are posts about replacement fans.
Fan wiring, Violet/Yellow +12v, Brown- ground.

There is a "test" sequence that you can do to check the operation of the fan relay/fan circuit. You should be able to find it in the stickies section.
The fan relay is controlled by the motronic, and the temperature is measured by the sensor mounted behind the fan on the small coolant riser tube bolted to the block. Power for the fan relay should be from fuse #7

You can check and see if you have +12v at the temp gauge on green/black. (key on, kill switch on, side stand up, engine off)
Wires at the gauge:
Green/Black- +12 in from fuse #1,
Black- +12 out from gauge to temperature sensor at water pump,
Brown- ground for backlight
Grey/Blue- +12 for backlight.
  • My Garage
Ride safe.


1997 K1100LT 0302488
1995 K1100LT 0302044
Garmin StreetPilot 2820
Garmin Zumo 550
"One who does not ask questions is ashamed to learn" Danish proverb

Offline Doodaadog

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Re: Cooling issues and fan not working K1100LT ‘92
« Reply #4 on: July 12, 2018, 09:01:35 AM »
Thank you gentlemen.....I’m learning all the time....will try your suggestions this weekend
Regards Greg
  • Lincoln, England
  • K1100LT 92
Ducati Monster 1200s
Montesa 315R
BMW K1100 LT

Offline Doodaadog

  • Motobrick Curious
  • Posts: 26
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #5 on: July 12, 2018, 09:13:03 AM »
Hi Laitch
Mine is similar but not the same as your schematic...According to my workshop manual...seems the K1100 LT and RS even differ?
Regards Greg
  • Lincoln, England
  • K1100LT 92
Ducati Monster 1200s
Montesa 315R
BMW K1100 LT

Offline Laitch

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Re: Cooling issues and fan not working K1100LT ‘92
« Reply #6 on: July 12, 2018, 11:46:18 AM »
Hi Laitch
Mine is similar but not the same as your schematic...According to my workshop manual...seems the K1100 LT and RS even differ?
That diagram is from MaxBMW's K1100 parts fiche. What BMW does with these diagrams is they will use the same diagram for many models even though there might be slight differences.
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.

Offline bizzaro

  • ^ SuperNatural Motobricker
  • Posts: 547
  • Season Closer Nov.- Churubusco,NY
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #7 on: July 12, 2018, 03:18:28 PM »
 [ Invalid Attachment ]

This is the fan test that Scott mentioned to check and see if the wiring, circuits(relay), and fan are working.  On center stand, ignition off, side stand up, ground pin one of your diagnostic plug with a wire to a good ground.  The diagnostic plug is right under your seat. Mine is a black 3 pin with a blue cover.  (And I assume yours should be the same.) With the ignition off, Remove the cover and ground Pin 1.  There is a good ground right behind the coils. Turn on the ignition, but do not start the bike. With the 1 pin grounded on the diagnostic plug and ignition on,  Count to 5, and Remove the ground. Your fan should now pulse on and off till you turn off the ignition. If it doesn't you need to start testing your components. I just replaced my fan and have a pretty good photo montage which I hope to post as soon as I learn how to crop, size, and orient photos so as not to waste bandwidth.   
  • Vermont
  • Current:1994 BMW K1100LT, 1989 Harley 883 Previous: 1982 Yamaha virago 920,1973 Honda CB550,1976 Yamaha 650 Special
See Ya in the Twisties,
 Bizz

Offline bizzaro

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  • Season Closer Nov.- Churubusco,NY
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #8 on: July 12, 2018, 04:54:03 PM »
Oh, shit. Not positive if this works with a 92? Mine is a 94.  I am sure we will know shortly, but I think it is still a valid test on your bike?  :dunno2:
  • Vermont
  • Current:1994 BMW K1100LT, 1989 Harley 883 Previous: 1982 Yamaha virago 920,1973 Honda CB550,1976 Yamaha 650 Special
See Ya in the Twisties,
 Bizz

Offline Scott_

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Re: Cooling issues and fan not working K1100LT ‘92
« Reply #9 on: July 12, 2018, 06:55:11 PM »
Unless Inge, or RBM know differently, it's my understanding that all 1100's use Motronic ignition controllers, so the fan test sequence should work.
  • My Garage
Ride safe.


1997 K1100LT 0302488
1995 K1100LT 0302044
Garmin StreetPilot 2820
Garmin Zumo 550
"One who does not ask questions is ashamed to learn" Danish proverb

Offline rbm

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Re: Cooling issues and fan not working K1100LT ‘92
« Reply #10 on: July 12, 2018, 08:46:11 PM »
Your 94 K1100 should be equipped with Mo_tronic 2.2 (changed in July 1993).  Fan test sequence should be the same for Mo_tronic 2.1, and Mo_tronic 2.2.

Documentation Link:  http://www.nt-guru.com/bmw/Motronic%20Fault%20Codes.doc
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/
2011 Moto Guzzi V7 Racer

Offline Doodaadog

  • Motobrick Curious
  • Posts: 26
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #11 on: July 13, 2018, 05:47:45 AM »
Thanks guys am trying this today....
  • Lincoln, England
  • K1100LT 92
Ducati Monster 1200s
Montesa 315R
BMW K1100 LT

Offline Doodaadog

  • Motobrick Curious
  • Posts: 26
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #12 on: July 13, 2018, 08:13:25 AM »
UPDATE;
Tested supply to the temp gauge...
Have 12v to the backlight and 12v supply from fuse....
Only milliamps to the black wire
Ground is good.

Fan test:
I can hear the relay firing and checked the loom feed to fan and sure enough 12v was pulsing through.
So conclude the fan feed circuit is ok.

Will next check continuity to fan.....but suspect fan is toast....
Have already tried putting 12v direct to fan....’ fan no likey’

Thank you all for your invaluable advice with this saga...
Regards Greg

  • Lincoln, England
  • K1100LT 92
Ducati Monster 1200s
Montesa 315R
BMW K1100 LT

Offline bizzaro

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  • Posts: 547
  • Season Closer Nov.- Churubusco,NY
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #13 on: July 13, 2018, 08:44:42 AM »
Robert, yes I have the 2.2 motronic.  I wasn't sure if they changed the test sequence on different motronic models. 

Unless the wiring to the fan has an issue, sounds like your fan is toast. So you have options now.  And just so ya know, buying the BMW replacement for $350, shouldn't be one of them! :yow I replaced my fan with a Spal Fan.  If you go this route You will need to use the old housing to mount the Spal Fan in place. You can also just replace the motor.  And there is a European co. Making a really nice replacement for about $140 I think it was.  You can peruse this thread here, http://www.motobrick.com/index.php/topic,11345.0.html  and here are a few links to options.

https://www.amazon.com/Spal-30100402-Puller-6-5In-15Amp/dp/B01LXF8FWE/ref=sr_1_3?s=automotive&ie=UTF8&qid=1529794718&sr=1-3&keywords=spal+cooling+fan+6.5

/https://www.amazon.com/gp/product/B075FSCHZC/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

https://www.tills.de/product-112-113-158.html
  • Vermont
  • Current:1994 BMW K1100LT, 1989 Harley 883 Previous: 1982 Yamaha virago 920,1973 Honda CB550,1976 Yamaha 650 Special
See Ya in the Twisties,
 Bizz

Offline Doodaadog

  • Motobrick Curious
  • Posts: 26
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #14 on: July 13, 2018, 10:30:25 AM »
New update.....yep fan is toast....the ‘live’ brush was burnt and broken off.....
If I could get the brush an easy cheap fix....will investigate

Can’t easily remove fan from rad as the fixings are so corroded, going to plump for used fan and rad...(guaranteed tested) by the seller....as I’m selling this brick on once I’ve got everything working again.
  • Lincoln, England
  • K1100LT 92
Ducati Monster 1200s
Montesa 315R
BMW K1100 LT

Offline bizzaro

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  • Posts: 547
  • Season Closer Nov.- Churubusco,NY
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #15 on: July 13, 2018, 05:17:52 PM »
Geez, that looks hauntingly familiar!
  • Vermont
  • Current:1994 BMW K1100LT, 1989 Harley 883 Previous: 1982 Yamaha virago 920,1973 Honda CB550,1976 Yamaha 650 Special
See Ya in the Twisties,
 Bizz

Offline The Mighty Gryphon

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  • Posts: 3764
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #16 on: July 13, 2018, 06:23:50 PM »
Geez, that looks hauntingly familiar!

Yep, seen that too...
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '92K100RS White, '94 K75S Dakar Yellow
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'94 K75S "Cheetos"
'91 K100RS "Moby Brick Too

Offline Martin

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Re: Cooling issues and fan not working K1100LT ‘92
« Reply #17 on: July 13, 2018, 07:07:23 PM »
I just found my old one in the bottom of a drawer. It's been sitting in there for the last twenty odd years. I don't why I kept it, maybe I was hoping it would miraculously repair it 'self.  :dunno  I've found a new location for it in the bin.  :hehehe
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline bizzaro

  • ^ SuperNatural Motobricker
  • Posts: 547
  • Season Closer Nov.- Churubusco,NY
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #18 on: July 13, 2018, 07:56:23 PM »
Martin, on one of your dump camp outs, you need to fill up with shit you aren't, will never use and DROP IT OFF,  :clap:
  • Vermont
  • Current:1994 BMW K1100LT, 1989 Harley 883 Previous: 1982 Yamaha virago 920,1973 Honda CB550,1976 Yamaha 650 Special
See Ya in the Twisties,
 Bizz

Offline Martin

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  • Posts: 3442
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #19 on: July 14, 2018, 01:40:19 AM »
I'm one step ahead of you I've already taken two trips to the dump and one trip to the Salvos. I consolidated all my tools and took four good empty tool boxes plus a never used dual  halogen lamp set up to the Salvos.  I then realised I could have used the lamps to help heat up the floor tiles in the newly renovated ensuite so the glue would set a lot quicker.   :hehehe I am about 3/4 way the through the garage, then have to do the back shed and then apparently my wardrobe.  :dunno
Regards not so retired Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline Doodaadog

  • Motobrick Curious
  • Posts: 26
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #20 on: July 19, 2018, 09:27:03 AM »
New Update
You can buy the cooling fan motor as a separate item

http://www.euromotoelectrics.com/BMW-Motor-Radiator-Fan-K-models-1983-1995-p/fan-k427m.htm
  • Lincoln, England
  • K1100LT 92
Ducati Monster 1200s
Montesa 315R
BMW K1100 LT

Offline Laitch

  • ^ Quintessential Motobricker
  • Posts: 5415
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #21 on: July 19, 2018, 10:04:20 AM »
New Update
You can buy the cooling fan motor as a separate item
Is that what you did, or did you go with the whole radiator/fan substitution to accelerate you down the road to Flipdom?
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.

Offline Martin

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  • Posts: 3442
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #22 on: July 19, 2018, 06:03:50 PM »
OEM fan motors a known source of cooling failure. The Spal fans and in my case Davies Craig take the fear factor out of will my fan work. Spal has proven extremely reliable, I don't think I have heard of a failure. My Davies Craig hasn't missed a beat in nearly twenty years.
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline Doodaadog

  • Motobrick Curious
  • Posts: 26
Re: Cooling issues and fan not working K1100LT ‘92
« Reply #23 on: July 20, 2018, 05:42:28 AM »
Hi Laitch
Bought a used rad and fan combo for 60GBP.......swapped fan onto mine....was very pleased to hear it run on fan test....so have a spare rad to go on eBay and recoup some dough.

Next is to find the 2 coolant sensors at reasonable cost.....

Or dig a hole in the yard and throw some money in!......
  • Lincoln, England
  • K1100LT 92
Ducati Monster 1200s
Montesa 315R
BMW K1100 LT

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