How to secure A/C fan blade to motor spindle

[Jean-Pierre]

On my 75 (200,000 Km), the radiator fan blade assembly was never removed from the motor spindle, yet it just fell (hopefully not on the road!). Then 2 solutions, get another new blade assembly (official recommended procedure in Rover's documentation) or secure the blade assembly to the spindle using 3 screws which I did as follows:
- Remove the A/C-radiator motor
- Take advantage to visit the motor brushes (many posts on the forum) and be curious without fear!
- Position the blade assembly over the spindle and mark each of the hole position fully counterclockwise of the radiused slots (see attached pic)
- Punch each hole center & drill 2.5mm or 3/32" holes.
- Use a 3 mm/0.50mm thread tap et hand tap the 3 holes
- Cut slightly the edges the 3 blade assembly plastic tabs beneath the spindle plate so that the screw may go beyond the spindle plate
- Use 3x16mm screws, 3mm flat washers, lock washers and a drop of locktite (i.e both a belt & suspenders!)
-See results on attached picture

Note: Before refitting a used blade assembly or if you are fitting a new one, I suggest using the above procedure, since the original conception seems very poor to me.

[SMC Trading]

What a good idea, something MGR should have done in the first place

[baxlin]

Sorry, I'm not quite as keen.

The reason is that the fan rotates at high speed, and one of the things to look out for in a secondhand fan motor is whether the bearings are on their way out.

So, unless the three holes can be drilled very accurately, so that when the screws are put in, the fan will be perfectly balanced, I'd be worried that it will eventually shake itself to pieces ruining the bearings.

I too have had a fan come off the spindle, but the problem was that it had not been locked into place properly. The very simple solution was to ream out the hole in the centre of the fan a little more so that a socket could be put firmly and squarely on the nut, and, with the motor fitted to the car, turning the fan 1/4 turn or so anticlockwise until it was properly in place.

I think the danger is in re-using a fan that has been removed, I'd always use a new one

[Jules]

I don't think fan balance would be an issue here as the 3 bolts Jean Pierre has fitted are very close to the centre axis.
The blades themselves are not very accurately balanced IMO.
It gets my vote as a decent securing method.

Another method I used on my father's car over a year ago (still OK) was to re use the fan blades and secure with Blue Locktite around the boss.