BMW K bikes (Bricks)

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1Back to top Go down   K75 cooling sensor and fan Empty K75 cooling sensor and fan on Mon Dec 01, 2014 10:35 pm

bkhK75

bkhK75
active member
active member
I have been reading all the posts I can regarding cooling fans issues and I hope that I am maybe chasing a problem that doesn't exist.  A few weeks ago when it was still hot here I was sitting in traffic and my engine smelled like it was running hot.  I don't have a temp gauge but the warning light was not coming on.  When I got home I checked if the fan was running and it wasn't.  I put in a new sensor after checking that the fan motor was good, put new coolant in and I have checked continuity of related wiring, grounds, connections, etc.  Everything I could find here.

It is now cool weather here and I have not been able to see the fan running.  Is it normal for the fan to not run much?  How can I check the warning light to make sure it is operating?  Is the fan relay maybe not working?  I hope someone can help me find out if I really have a problem or set my mind at ease that everything is operating properly.  Thank you.

    

2Back to top Go down   K75 cooling sensor and fan Empty Re: K75 cooling sensor and fan on Mon Dec 01, 2014 10:52 pm

orforester

orforester
Silver member
Silver member
The best bet would be that your fan brush holder on the lower side has melted, and therefore the fan will not kick on.  Can you turn the fan?  That is the first test.  Then get the motor up to hot, not red, but close where fan should turn on, like run it on idle.  If the red overheat light comes on and the fan doesn't turn off the bike ASAP.  If the fan doesn't run, I would bet it is your fan brushes are toast. 

You can buy original brush holders/brushes, but here is a link ot a new motor which claims to be more heat resistant: 

http://www.euromotoelectrics.com/BMW-Motor-Radiator-Fan-K-models-1983-1995-p/fan-k427m.htm

I am sure there are better ways to check the fan than I have stated, but that is where I went.

Bob


__________________________________________________
89 K 100 RS se
85 K 100 RT
    

3Back to top Go down   K75 cooling sensor and fan Empty Re: K75 cooling sensor and fan on Mon Dec 01, 2014 11:56 pm

Be made

Be made
Life time member
Life time member
@bkhK75 wrote: It is now cool weather here and I have not been able to see the fan running.  Is it normal for the fan to not run much?  How can I check the warning light to make sure it is operating?
There are a lot of very experienced K spanner hands on this forum.

Be patient for your answer here before going too much further

I live in NZ it is not very hot here and the fan does not come on much on my K until summer kicks in unless I am sitting in traffic for a good 10 minutes or so. But then mine is an unfaired machine which might run a little cooler than a faired one

I assume it is normal for the fan not to work much. Bear in mind this is a car engine in a bike frame so it is getting a lot more air circulating around it than if it were in a car.

That said be cautious

If me I would not run long distance until all avenues had been exhausted, as to whether the fan is working as it should or not.

A temp gauge is a GREAT addition

    

4Back to top Go down   K75 cooling sensor and fan Empty Re: K75 cooling sensor and fan on Tue Dec 02, 2014 6:03 am

Inge K.

Inge K.
VIP
VIP
@bkhK75 wrote: How can I check the warning light to make sure it is operating?  Is the fan relay maybe not working? 

To check the relay and lamp you can ground the wire between the sensor and the relay,
then both the warning light should show and the fan start.

You can do this by grounding the contact marked E in the relay contact.
Have a look here, the relay you find in the relay box in the middle on the RHS.
The wire going to the E contact is violet/green...the relay must be present.

The same violet/green wire you also find at the connector between the engine
and the frame harness.
It's located under the tank at rear end on LHS, you can disconnect this connector
and ground the violet/green wire (at the frame harness side) at this place also.....
if you find that easier.


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

5Back to top Go down   K75 cooling sensor and fan Empty Re: K75 cooling sensor and fan on Tue Dec 02, 2014 3:00 pm

Be made

Be made
Life time member
Life time member
Nice. I LOVE This forum. Inge . . . . You ROCK  🆒 K75 cooling sensor and fan 112350

    

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