I have a 1979 300 sd (116). The brushes on the blower motor went bad. I put in a new motor. Before the brushes went bad it never blew a fuse

It will now run for a few hours and then blow #3 fuse.

I have done the following:

1) cleaned the fuse holder contacts
2) put in new mercedes fuses
3) disconnected the aux water pump
4) cleaned the ground connection
5) took the new fan out and re-unstalled it.

My #3 fuse is a 16 amp fuse....that is what the paper on the top of the fuse box says it should be. An old thread stated that his 79 300sd had a 25 amp fuse in #3. Am I putting in the wrong amp fuse??????What else could be causing this.

Thanks for your help

Augusta