My cooling fan is either fried or stuck. The local BMR mechanic spun it a few times to see if it might loosen it up, no luck so I am moving to R&R it. It has'nt been a problem, as normal riding on road no observed overheating.

Found a used one on e-bay for $95.00 so plan to change it it out.

Any suggestions on this issue and planned replacement?

whilst getting in there to do repairs, clean up the fan connector behind the radiator ...often found to be an issue ..you maybe lucky if you dissasemble the fan, just some lubrication may free it up .

try and find some deoxit ...commonly found at pro music shops ...its great stuff for cleaning up all electrical connections .

welcome aboard

KClass wrote:My cooling fan is either fried or stuck. The local BMR mechanic spun it a few times to see if it might loosen it up, no luck so I am moving to R&R it. It has'nt been a problem, as normal riding on road no observed overheating.

Found a used one on e-bay for $95.00 so plan to change it it out.

Any suggestions on this issue and planned replacement?

The fan is a commonly failing component of these bikes because it is always bombarded by road dirt, the sleeve bearing in the motor consequently gets seized from this grime and the poorly designed brush holders in the motor melt from current overload when the motor won't turn. Hopefully, you've just managed to catch it in time to avoid the melted brush holders. If you have, then cleaning and lubricating the motor bearings might breathe new life into the fan. If not, your only choice is replacing the fan. There is a document in the download section on heat management techniques for the K-bikes. In that document which I assembled, I included a couple of articles on how to replace the OEM fan with a modern brushless DC fan available at almost any auto repair / accessory store. The replacement fan will probably work better, last longer and be cheaper than the OEM fan. One trick I saw someone do was put a dollop of JB Weld on the radiator fins just in front of the fan's axle. Ostensibly, it was to prevent the fan from drilling its way through the radiator but it also protected the sleeve bearing from debris.

This document could also be helpful.

Brand new fan motor here http://www.euromotoelectrics.com/SearchResults.asp?Search=Fan+motor

KClass wrote:
Found a used one on e-bay for $95.00 so plan to change it it out.

Any suggestions on this issue and planned replacement?

you´ve got a typical K damage . usually K75 owners are more often strucked because of the "not in use" effect.

Forget used stuff
get the Bosch engine new and follow the instruction Inge just posted
and clean the cooler inside & outside - use the bathtub for that but be shure your "best part" has other things to do - far away

more see: K- WIKI
in your case : BMW group 17 / cooling
but first: RTFM

KClass beemer bone yard in NJ has new fan motors. Much better then a used setup. I has to change mine out at the national rally 2 years ago and it is not a problem. They have them in stock.

First, mea culpa for the delay in getting back to this and your suggestions. I was preoccupied with snow blowers and ice melt the last few months...

With just a few snow piles remaining I rolled the bike out in 25 F and took her for a 25 miler...so I am back on point to finish the maint items. At least yesterday a non working fan was'nt a problem.

Based on the posts I have some good options, thanks for the suggestions and links all were good to consider.

At this point I am pretty confident that the brushes are fryed. I had a few times in traffic last summer where the bike was stopped and the hot light flashed so the fan is not working...

I have the Haynes Manual and plan to either replace the motor or complete fan assembly. Based on my local Bemmer shop it sounds like a several hour project. If there is anyone who has done this project and can impart their experiance on the best R&R steps, other suggested maint while I replace the fan please pass it along....

You will have no problems with a naked bike.

Drain the coolant.
Unplug tank power
Unscrew fuel lines. They are under pressure and will spill fuel
Remove the tank.
Remove the radiator cowl.
Unscrew the filler cap from the frame
Undo the other two hoses where they connect to the radiator
One screw hidden at the top of the radiator holds it to the frame
Unplug the fan clip just around the fan motor.
Lift the radiator, wiggle and tug it away from the hoses.
Spill the remaining contents of the radiator on your legs and garage floor.
Unscrew the fan.
Reverse process to re install

Undo the negative battery terminal first, gets rid of any chance of a spark in spilt fuel.
I just took my fuel hoses off after 2 days of not riding and there was hardly any squirt in the hose, but the tank will drain fuel out of the return line spiggot if it leans to the left. Join both fuel pipes together with a piece of fuel hose, one end on each pipe, stops leakage as you move it. Hmmm what is that oily stain on Mother in law's front porch.
RT

Thanks for the check lists...

I replaced my fan a few years ago after a few episodes of overheat light coming on. I did a lot of miles before a hot summer day caused the problem to be apparent.

My search took me to above links and from memory you will find the Bosch still has the motor on their books. Also Bosch used these fans in cars as internal fans for air cons and climate control so they are not rare.

The major difference between NEW and OLD versions seems to be in the way the brushes and bearings are mounted. I think that they also improved the bearing mechanics. BTW they supposed to spin at 4100 rpm, so a free spinning system is needed for effective cooling, at least during hot summer days.

Naked bike? YES!

If you need a new fam motor here is the place http://www.euromotoelectrics.com/SearchResults.asp?Search=fan+motor
He also has lots of other goodies ar quite reasonable prices.

Well done Mark!

Great photos and great instructions!

Post a report after a few weeks to see how things are going please.

Following similar advice, I bought a new fan motor from Euromotoelectrics. Resurrecting the original bearings would have been possible, but not the melted brush carriers!

Advice given by others above is correct from my experience as well. Having an RT, fairing removal had to be done, so more work than a naked bike. Needed fairing off for other work anyway, so no extra in this case for me.

Just another witness to the value of this forum and its helpful experts.  

Cheers,

Bill

Follow up...

The above Mod works very well.

Please note, you do need to reverse the polarity so the motor sucks and does not blow.....

The only thing that sucks on a K

I presume the reversal of the polarity is due to the fact that a lot of car cooling fans sit in front of the radiator rather than behind as on the K.......

But in shorter term if you have a fan problem one option is to simply kill the engine as soon as you stop if you are in traffic. I went with no fan on my LT for a long time doing that......admittedly its much cooler here but it worked.

The only thing that sucks......
True that......

Turning the motor off did work in winter to a degree (HA HA).....
It will be 35 degrees Celsius today, having no fan is no longer "cool".....

It would appear that my fan has died today. Probably partly due to loads of salt on the roads and also me riding it quite a lot in the rain before Christmas.

Along with this, the biKe had not really been used 'properly' for the last six years or so not even clocking up a thousand miles in total in that time!

Oh well, looks like a fairly easy job to do. Anything I should look out for when fitting a replacement? I'll most likely be getting one from Motorworks as they are not massively far away from me and it's quite a pleasant ride over there, or at least it should be this time with a properly working clutch cable!

Brick fan upgrade ("So these radiator fans are crap.")

I followed this guy's idea and I'm still amazed how much better this simple upgrade works. Easy install and superior to the old-tech OEM unit.

Spal 6.5" puller fan