Hi Guys,

The fan does not appear to be cutting in when it should. In the pic below is the temp gauge. In normal motion the needle is straight up so I assume it is probably working OK. If i leave the bike idling the temp rises. It has got as far as where I have marked the gauge in yellow before I turned the engine off or went for a ride to cool it down - for fear of damaging the engine. I am assuming the fan should have kicked in before this?



I have taken off the fairing and accessed the connection to the temp sensor beneath the bottom of the rad; it snicks into place and seems to connect OK. I cleaned it with Deoxit and left well alone. Also cleaned the connection under the tank.

I've just put 12 volts directly through the fan at the connection under the tank - and it works! Great, no new fan needed. The fuse is also fine - cleaned and wiggled all the fuses with Deoxit.

Advice on my next step please. Remove the temp sensor?

Thanks as always
Dave

Hi,

This is quite a common problem and questions about the troubleshooting procedure come up from time to time. The following previous responses might help you along the way to a diagnosis:

http://k100rt.aforumfree.com/t4287-cooling-fan-fuse-location-and-fan-testing

http://k100rt.aforumfree.com/t4093-overheating

http://k100rt.aforumfree.com/t4462-cooling-system-issues

These are just a few links that came up under a search. You might find other useful information in the Motobrick forum. Duck does a great job of documenting common procedures with the K-bikes. You have yet to eliminate the fan relay as the culprit and, since it is a complex circuit rather than a simple relay, the issue might well lie in that component. It is often vibration that cause solder joint failure that leads to overheating and fan issues.

I have had this issue on both of my K's and in both cases it turned out that the fan was seized and would not turn easily or at all. The method to check this is to use a stick or a long screwdriver through the fairing vents to see if the fan spins freely or not. I replaced the fan unit on both of my bikes and regularly spray the fan bearing with GT85 or WD40 or similar. I have had no issues since - hope this helps

Hi Dave,

That's exactly where my fan kicks in. Try giving it just a little bit longer.

Fan should start and stay on until temp is reduced to normal.

GerryP wrote:Hi Dave,

That's exactly where my fan kicks in. Try giving it just a little bit longer.

Fan should start and stay on until temp is reduced to normal.

+1...on my K11 the fan kicks in even later, just a tad before the needle enters the red field.

To check that the relay functions, disconnect the Motronic connector and ground contact # 16.

Mine is the same as Inge's just before the red.

Thanks Guys for all teh answers. First step I'll let the engine get a bit hotter and seee if it works!

Cheers
Dave

Hi Dave,
I suggest you have a poke with a wooden stick and make sure the fan blades turn because if it is jammed you are just wasting fuel, if it's jammed it isn't going to start Once you know it turns freely then go ahead and do your warm up test.
Regards,
K-BIKE

I also have suffered from seized fans on 2 of my K's - use that stick first.

I have just read the the beginning of your post again and realised the fan is working after you powered it up, so stick won't help, one of my K's only kicked in the Fan when it hit the Red on the temp. gauge you may need to let it warm up a bit more

Yeah thanks Guys. The fan is working I probably just haven't had it hot enough for it to work! I didn'yt want to cook the engine and thought it woukd have clicked in by 75% but I guess it might click in higher up the temp range . Still , now I've broken my water temp sensor connector while changing the oil/water pump seals I might well be in blissful ignorance for some time to come!

bugga dave ....oh well ! we learn new stuff i guess .

GerryP wrote:Hi Dave,

That's exactly where my fan kicks in. Try giving it just a little bit longer.

Fan should start and stay on until temp is reduced to normal.

So do mine
Best regards
JAP