The fans are a press fit. No glue.

Those describing the brute force method are describing another model. The W124 fan would not survive.

Compress Ignite has the right idea with the puller, although I don't know what he is catching on.

I made up 2 disks, one goes behind the fan and the other on the outside. They are screwed together and then a small puller catches the outer disk to pull the fan off. Because they are screwed together it is actually the inside disk that is exerting the force on the fan at the strong area where it is pressed on the shaft.
Took 2 aluminum disks (steel would of course work as well) 1/8" thick, 2" diameter and drilled a hole though the center of each the size of the motor shaft. On the disk that is to go on the inside, cut a slot with the width of the shaft diameter in from the circumference to the center. Mark the 2 disks in 3 spots (more or less equally spaced) so that screws can go between them without touching the delicate fingers that attach the fan blades to the center part of the fan. Drill clearance holes in the outer disk and tap the inner one (I used 10-32 x 1 1/2" screws).
For use on the later W124 fans with the cabin air filter, I had to Dremel out some metal from the inside disk as the clearances are tighter between the fan and motor than the earlier blowers.

Lubricate the fan bushings with transmission fluid before putting it back in the vehicle - avoid getting any on the commutator and brushes (syringe works well).