1995 K75 Radiator Fan Motor Replacement

[72r60/7]

I need to replace the radiator fan motor and haven’t decided to replace it with the whole spare used unit with blades, or the new motor, without blades, that I’ve had for a while for just this sort of situation. The new motor does not have the blades attached and I would have to use the existing blades on the new motor.

I’ve always wondered how to take the existing blades off the shaft and reinstall them on a new motor.
Is it as simple as it sounds ?
I’m pretty good at taking things apart.

Any pointers may save the experience of learning by not doing that again. (i.e. breaking things)

Thanks
Charlie

 

[beemerphile]

The fact that the blades sometimes come off the shaft by themselves and dig into the radiator is one reason that many people use an aftermarket brushless fan, the most commonly applied being a SPAL 6.5" puller. If you do a motor replacement, be careful pulling the old blade assembly from the motor shaft, as that is the part you will be re-using.

 

[72r60/7]

Which brings up the question: Is a press fit the only fan blade reattachment method or is there some adhesive used ?

It’s been awhile since I bought the motor and more than likely it came from Euro Moto Electric (Great Company), so hope the shaft is the same size.

I may be leaning towards using spare motor and housing unit . Having a new spare motor is better than
“A Bird in the Hand........” though I would tend to carry the new motor for a while when traveling.

Charlie

 

[beemerphile]

Which brings up the question: Is a press fit the only fan blade reattachment method or is there some adhesive used ?

It’s been awhile since I bought the motor and more than likely it came from Euro Moto Electric (Great Company), so hope the shaft is the same size.

I may be leaning towards using spare motor and housing unit . Having a new spare motor is better than
“A Bird in the Hand........” though I would tend to carry the new motor for a while when traveling.

Charlie

I think the EME motor will fit without issue. I haven't heard of any ways to supplement the press fit, though some people have JB Welded a rub pad to the radiator so that if the impeller does work off it won't auger in to the radiator. I don't see the need to carry a spare because you are not sidelined if it dies. One reason the fans die is that they seldom activate. You only need it in stalled traffic. As long as you are moving, the motor is unlikely to overheat (though you and the gas tank might).

 

[6322]

Charlie,
I just went through this on my '85 KRS, with the added complexity of having an EML sidecar attached. The sidecar has a subframe that blocks the removal of the radiator/cooling fan assembly so I had to remove it from the rear. This made just changing the motor make more sense. I had a similar question regarding separating and reinstalling the fan with the motor. I had no issues with either. Just was careful to remove the fan from the shaft evenly using a flat screwdriver and made sure that it was pushed completely back on the shaft when I was done. I used the same motor from the same source as you've described. You shouldn't have a problem but PM me if you need more info. Also have you priced the new fan/motor/shroud assembly? Ordering another motor, if you want a spare, still makes more sense. Good luck with your project, and fly that brick!
gp

 

[72r60/7]

I removed the radiator from the front. Cut the plastic protective motor cap to remove the motor plug with the motor. I’ve done this before but don’t remember a thing about it. Poked around and decided to use the used unit and keep the new motor as backup.

I did try to pry the fan from the existing suspect unit. Suspect because the motor was making noise sometimes when hot. It came off after an initial gentle attempts didn’t budge it. It was a slip/press fit that was secured by a small amount of rust on the end of the motor shaft. Easier than I thought it would come off.

I would not worry about the fan coming off the new motor shaft unless I put it on. Would not even veture to guess at type of adhesive would set my mind at rest. Long term effects of “Paralysis from Analysis”.

Forgot to bench test the used unit, but road tested it @ 88° (Air temp) and the fan was quiet and smooth and cycled on and off several times. I have a steep 1/4 mile driveway and the fan comes on at the top regardless of Summer or Winter. Never understood that.

Charlie

 

[6322]

Well done. Kindof the same experience I had other than having to remove the motor from the back. Rideon.
gp

 

[pjar]

Charlie, I too had done this replacement using a new motor and removing and installing the old fan blade. Looks like you already have solved that issue by using the used motor. Here is how I removed the old blade and installed the new.

Cut circular hole in plywood wooden box, the hole just slighter larger than the motor, and box taller than the old fan motor. Placed motor through the hole and let it hang by the fan blade. Then gently tap (with an appropriately sized drift) the center shaft of the old hanging fan motor until it is freed from the blade.

To install old blade on new motor: I used a vice to support the new motor and with a socket over the fan blade tapped it into position. The key here is to support the back end of the center shaft of the new motor when tapping on the blade, to avoid putting stress on the shaft.

I'm sure there are more elegant and expedient ways of doing this. Just my method. It turned out to be comical (to me) because it took me about 5 hours of prep (buying and mounting a vice and setting up the hole jig for removal) to do approximately 2 minutes of actual work.

It has been about 3 years since installment and fan is still working perfectly.

 

[72r60/7]

Here is how I removed the old blade and installed the new.

Cut circular hole in plywood wooden box, the hole just slighter larger than the motor, and box taller than the old fan motor. Placed motor through the hole and let it hang by the fan blade. Then gently tap (with an appropriately sized drift) the center shaft of the old hanging fan motor until it is freed from the blade.

To install old blade on new motor: I used a vice to support the new motor and with a socket over the fan blade tapped it into position. The key here is to support the back end of the center shaft of the new motor when tapping on the blade, to avoiding putting stress on the shaft.

I'm sure there are more elegant and expedient ways of doing this. Just my method. It turned out to be comical (to me) because it took me about 5 hours of prep (buying and mounting a vice and setting up the hole jig for removal) to do approximately 2 minutes of actual work.

It has been about 3 years since installment and fan is still working perfectly.

pjar

Good information/theory for someone who has to do this for the first time. Especially should they stumble upon this thread thru “Search”.

Your post is a little confidence inspiring for shade tree mechanics (i.e, me), or anyone doing this the first time, because my memory of earlier discussions of years gone by, was of “ you are probably gonna break the fan” and then you are gonna wait a week for a new one and its maybe $200 and it’s already mounted in the housing you don’t need.

Charlie

 

[anglojaxon]

Motobrick.com has a few threads on replacing the fans.

Here's a good one...

http://www.motobrick.com/index.php/topic,11345.0.html