Hi All:

     I bought a set of bearings for my engine yesterday that were shielded.  The original bearings were the open type and the chap at the bearing supply house told me that the shielded bearings were lubricated with grease for life.  He suggested that if I did not like the shields, I could pry them off and run the bearings as a standard bearing.

    What should I do: Run the bearings as shielded or remove the shields.  Oh yes, all that he had in that size were stainless steel.

     How is the best way to remove the shields?

                                                                                                              Tia,

                                                                                                              Frank McCune 

Bearings with grease are sealed bearings and I believe there's at least one 4 stroke that uses them for the main bearing. Sheilded bearings usually have a metal shield on both sides but there's a small gap near the inner race where oil can flow through. IOW they're not sealed. Some engines use a shielded front bearing but others use an unshielded bearing, kind of depends on whether the prop driver wraps around the front of the crankcase like the ST does to help keep out dirt. I've used a sealed bearing as a front bearing to cure a massive fuel leak but removed one rubber seal and washed out all the grease first.

I would say that there are three basic options: Open bearings, shielded bearings and sealed bearings. I would prefer shielded (that usually means on one side only), but have used a sealed bearing with one seal removed. I'd only use an "open" bearing for the main bearing, and a shielded or (one side) sealed bearing for the front. I can't recall if I hosed out the grease when I used the sealed bearing or not. It would probably be a good idea to remove it. A good blasting of WD-40 or carby cleaner should do the job.  Steve

The OS Max-H 40 I changed bearings on recently had the front bearing installed with the shield on the aft side and the front open! That bearing was actually OK when it was cleaned up. The rear bearing, unshielded, wasn't in very good shape though.

I followed Bocas instructions as the front bearing they supplied was shielded on both sides.

The only sealed bearings I see in the aviation industry are used in applications undergoing very limited rotation, like flight control rod ends.

The only sealed bearings I see in the aviation industry are used in applications undergoing very limited rotation, like flight control rod ends.

I'm pretty sure that at the speeds we run things you want continuous fresh oil on the bearings.

'lectric motors may be a different story -- but I claim no expertise there.