BMW K bikes (Bricks)

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1Back to top Go down   coolant light intermittent K75 Empty coolant light intermittent K75 on Thu Oct 29, 2015 8:13 am


Gold member
Gold member
HI Folks,
My mate has a 94 K75, that has just 18,000kms. It had been stored for a good few years, and when he recently got it he replaced all fluids, tyres and battery and it looks brand new. However there is an intermittent problem where we will be riding along and he will tell men that his coolant light comes on, now the temp gauge remains in the middle and after a few seconds the light goes off. He has done about 2000km and the light does not come on every ride.
Considering the pristine condition of the bike, it was dry stored, any ideas.


2Back to top Go down   coolant light intermittent K75 Empty Re: coolant light intermittent K75 on Fri Oct 30, 2015 7:21 am


Life time member
Life time member
I can think of three possibilities.

If he changed fluids including coolant, he might have an air bubble in the system.  Try massaging the lower rad hose to expel air in the system while the engine is idling.

It's possible the overtemp relay is acting up.  Try cleaning contacts.  If that doesn't help, open the relay and inspect the soldering joints with a bright light and strong magnifying glass.  The solder joint can fracture and cause weirdness.

The last possibility is the water temp sender or wiring. The overtemp light comes on when that sensor closes and grounds the circuit. It is not connected electrically to any temp gauge (separate sensor and wiring). So, maybe chaffed wiring is momentarily grounding, or maybe the sensor is bad. Check everything around the water pump.

1987 K75

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