K75c questions

[dyoungen]

I've had my k75c bike since it was new. Back in the spring it quit running for no reason. I finally found out the ground was the problem. Fixed that and the mas failed. I thought the temp was running hot, just replaced the fan earlier. and the radiator got hot as soon as the bike started warming up like the thermostat wasn't there. i looked at another post here and they mentioned a jigglier in the thermostat. mine doesn't have one of those and my bike is totally original. Where is the sensor to turn on the fan? my fan never did come on even after hitting 200 degrees. I'm using an IR thermometer.

[Laitch]

. . .  my fan never did come on even after hitting 200 degrees. I'm using an IR thermometer.

That's because it doesn't turn on until approximately 220ºF.

[dyoungen]

OK, That answers that. I read in the manual about the temp opening the thermostat starting at 185 and completely open at 190. i'll have to let the temp get higher when i get a new thermostat. any suggestions on which thermostat to use?

[Laitch]

I've had my k75c bike since it was new.

How about posting a photo in the Klassic K-Bike section, dyoungen? Put the bike's year in your profile, too, so it will show up in every post. Head on over to the site's Technical Library index. In it you'll find a trouble shooting chart describing all the functions of your bike.

How many miles have you put on your bike? When did you last flush the cooling system? My guess is that you haven't yet.

You might have several things going on at once. You'll find suggestions for thermostats in the Technical Library. I'd use OEM. MAX BMW has a parts fiche that will show general locations of your parts. There are several threads on the site that explain where the sensor is. The easiest way to get to it is to remove the air box.

[dyoungen]

Good idea. I'm new here and have a lot to learn. Thanks for the info!! my bike is a 1986 k75c. not sure how many miles on it as the odometer stopped a few years ago. First time it stopped it had right at 6,000 miles and after that the meter stopped at 96,000 some odd miles. BTW, I did flushthe coolant system few years ago.

[Martin]

OEM fans had a lot of problems if they weren't run regularly, they tend to seize. You need to make sure the fan is not seized by putting your finger  ( finger, stick,screwdriver) into the back of the fan blades and see if they rotate freely. It is a good idea to fit an override switch so that you can give it a spin occasionally to make sure it is free.
Regards Martin.

[dyoungen]

I was working under the tank and tried pushing the fan and yes it was like trying to push something thru frozen STP. I've already replaced the fan and motor. i tried the new fan and motor and it spins freely.

[Laitch]

I've already replaced the fan and motor. i tried the new fan and motor and it spins freely.

Now, drain the coolant, flush the system, replace the thermostat and replace the coolant with 50:50 or 60:40 longlife coolant/distilled water according to this article.  Clean the expansion tank and its line. Flush debris from the radiator fins.

[dyoungen]

Planning on everything you mentioned. Thermostat ordered, will buy the gallon of antifreez and distilled water then change everything saturday. Would it be a good idea to run sosme radiator flush thru the system? :yes

[Martin]

Fit an override switch to your fan, since fitting a non OEM fan ( Davies Craig fully sealed car fan) and a switch I have never had a problem. It will give you the ability to check the fan and run it in heavy traffic earlier.I also do regular coolant changes with distilled water. I have been using OEM coolant as it is the only thing I can find from BMW that is relatively cheap. :hehehe
Regards Martin.

[Laitch]

Would it be a good idea to run sosme radiator flush thru the system? :yes

Yes. Follow the instruction in the link in my previous post.

[dyoungen]

I picked up the gallon of antifreez and the gallon of distilled water. Now all i need is the time to work on it. My truck is down and it's my DD so that comes first. As soon as i get back to the bike i'll post the results. Tanks ahead of time!!!