Radiator Fan

I need to purchase a radiator fan for my '89 K75C. Dealers want $125-160 for BMW stock unit. Just my humble opinion, but that seems a bit steep for what the part is.

I can easily justify the cost, after all, $160 is much cheaper than turning my engine into a giant toaster, but if I can get essentially the same thing for less and still get a quality unit, why not?

I looked at www.beemerboneyard.com, but they were sold out at the moment - plus, how do I know as used fan it isn't going to grind to a halt shortly after installation? Some parts seem OK to buy used but probably not a fan motor.

http://www.ibmwr.org/otech/partsubs.html#KOilfilter2
This link says that Bosch made one for some models of Porshe 911 A/C units, but the part numbers they list don't seem to ring any bells at either Porsche dealers (I have owned Porsches before and will again, so I find it a little amusing to be calling a Porsche dealer to see if I can save money on my BMW!) or places that handle Bosch motors and accessories.

Shall I just suck it up and pay the dealer, or do any of you have suggestions?

I feel your pain. The fan is one of the most popular parts to replace.

My fan died on a trip to Ensenada in November 2003. As long as I kept moving I was ok. I split the mile long line up at the border on the way back.

At first I bought a fan from http://www.thepartshaus.com/ for $65 and it was from a 1985 bike and I didn't know how many miles were on it. Feeling uncomfortable about that, I bit the bullet and bought a new fan for $125 at the time from the dealer. I sold the used fan on ebay. I just looked at Max's parts fiche... $157! They've increased the price considerably.

I would call this Bosch parts/service company: http://www.rosenthalservice.com/ and ask about the Porche part number in the ibmwr.org article. This place was near our old office in Palo Alto.

The K75 is one of the most reliable bikes, but when it does break, it will cost you. That's the price of owning a reliable bike.

I always thought of gettting a part time job at a dealer sweeping floors so I can get the BMW employee discount.

I put a new fan in my K75 before I took it to Italy, and tried to sell my perfectly good old one for $50. No one wanted it. Now I picked up another 17-year old K bike that uses the same fan, so I guess I'll keep it around.

FWIW, I've purchased 3-4 of these fans over the years, and don't recall ever paying less than $100-110. I think they've always been expensive.

Ebay is probably your best opportunity. That's how I found mine I believe for under $50

mullerjd1 said:

Ebay is probably your best opportunity. That's how I found mine I believe for under $50

Click to expand...

Were you able to buy a new fan on eBay?

deancox said:

Were you able to buy a new fan on eBay?

Click to expand...

No, it was a used unit but it looked like new and works great. I had no idea mine was even seized up till I was stuck in traffic one summer day, it was probably bad since I got the bike. Anyway, there's a good looking one on Ebay now for $87.. Auction number 4577552927

Cooling fan

Based on the premise that since it is already broke you can do no harm!!! you may try to lubricate the bearings. I bought and replaced the fan on my 85 k100rt, that has over 100k on it. I know it was over $100. I then decided to autopsie the old fan. The fan was not burned, had good brushes. the only thing was that the solid brass bearings were dry. It comes apart by the bending of tabs. and I think I could of reassempled it but didn't as I already had the high priced one installed. Has anyone tried it. I know it is a lot of work just to get in there and back out and not have it last an other 100k.

I have 'messed' with little electric motors before and it isn't all that hard to give it a try. At worst you have to buy a new one, which you are set to do anyway, and at best you get to fix the thing and get some more miles out of it. If it isn't burnt up electrically, than usually the bearings are stuck. Oil will work to loosen the thing, but a dab o' grease will last longer. Just some pennies here..

Dean,

What happens to the fans is this: they run rarely - the K75 has a lot of radiator area - and therefore get gummed up. The lube thickens, or whatever. Anyway, the motor don't turn easily after a long time of not running. Then, when the thermoswitch finally turns it on, the torque generated by the electric motor is insufficient to turn the armature. Current flow w/o interruption -> excessive heat -> melted bush holders. The holders are plastic.

I've never heard of the bearings (well, the bearing surfaces, they're not ball or roller) going bad, they just get dirty, hard to turn, with the above results. If things aren't melted too badly, you might be able to repair the brush holders.

Some have installed a switch in the wiring, so that they can manually and occasionally run the fan. Others reach in (when things are cold!) and spin the fan periodically with their fingers. Others leave things to fate.

The motor is neither fancy nor big; one might be able to fit another similar-sized unit in the place. I'd feel confident that any used motor that spins with your finger is in good-enough shape to use: they don't wear out, they fail after not being used.

I'm aboard w/dbrick:
1> if you catch it when only not free spinning, good chain lube works well
2> if flat frozen, hopefully the brush holder hasn't melted; not trivial to reconstruct

I reach in & give it a spin every month or so, just to check.
Rarely used, always in the heat & rain is a bad environment for a sleeve bearing. If there were a big enough demand, a sealed ball bearing motor could be made available. It's a matter of time to find. G.H <<<)))

Thanks everyone. I will pull it, clean and lube it before ordering a new one.

I had a cooling system burp on the K1 Valdez several years ago due to the temp switch not switching on the fan. Since the switch is buried way down deep, I stopped at a BMW dealer and we wired in a switch to the fan relay to turn it on with/without the temp switch.

Now, whenever I'm pulling off the road after a fast, hot run, I flip on the switch and know the fan is already starting to cool down the engine before it gets so hot the temp switch finally comes on. Good for slow moving traffic on hot days.

It's just a matter of finding the relay in the electrical box and determining the correct wires to tap into. My memory sez yellow and purple, but that could be wrong.

pmdave

My fan on my 96 K1100RS slide partially off the shaft and was hitting the radiator. Luckly I caught it in time before it did too much damage. the fan is just an interference fit on the shaft. After that i heard that this is a common occurance. If the fan is not turning make sure it isn't hitting the radiator

I can turn it by hand, but it is stiff and does not come on when it should. As soon as I have a little time, I will pull it and inspect it.

deancox said:

I can turn it by hand, but it is stiff and does not come on when it should. As soon as I have a little time, I will pull it and inspect it.

Click to expand...

It's dead. Deceased. Passed on. Nailed to the perch..

There is at least one for sale on the IBMWR marketplace - I seem to remember $75 or $85..

When you get the new one - dribble some motor oil (synthetic of your choice) down into the bearings as best you can (the one is almost impossible to get to unless you pull the blade.) These are "oillite bearings - sintered bronze, and they will absorb the oil (very very slowly). Try to keep it away from the brush area of the motor.

HTH,

In the interests of the overall health of the bike and my peace of mind, I'm going to buy a new one and stop being so cheap (at least on this particular issue.)

A belief in phoenix...

... or perhaps a disproportionate belief in myself (no news conference here).

If you'll part with the dead one (so long as the rotor isn't frozen solid & brush assembly intact), I'd be happy to cut you a check for shipping it to me. I've resaturated sintered bronze bearings & have no problem putting it back into service after a careful reburb. Please PM if interested.

New is oft considered better, when it is sometimes just back to square 1. I'm of finding the nature of the problem and addressing it, such that it's not likely to fail in the same manner again. (The probability of "not likely" is about proportional to the quality of the reengineered answer.)

This rubs purists poorly (yawn)... <<<)))