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I am about to reinstall my F3L912 after a COMPLETE rebuild, and I felt the cooling blower bearings were suspect, so I opened it up with intent to renew.

The blower shaft runs on two 6204 deep groove ball bearings, sealed on the outside, open on the inside. My service manual contemplates filling the space around the spacer bushing (which separates the bearings, but does not fill the bore) half full with special Deutz F5 hot-running grease. I am having no luck finding any such grease, and, even if I did, I am not sure this is the best method of extending the service life of these bearings.

My thinking is that grease laying around in the bore next to the open side will not ideally replace any lost oil next to the balls themselves, and if it is fluid enough, it may tend to churn and add heat, so the surplus grease seems at best more like a placebo.

I am now considering replacing these bearings with double-sealed bearings, hoping to preserve the initial lubrication as long as possible, knowing that at some point they'd need to be replaced (but hopefully a long way down the road).

Now I am struggling with the choice between CN (normal clearance) or C3 (which, if I understand correctly, has up to 0.0003" greater radial play).

I know I am probably overthinking this, but I'd greatly appreciate any experience or opinions on this. Should I follow the book and keep looking for the Deutz "F5 hot-running" bearing grease (or equivalent); or should I simply use double sealed bearings and be done with it?

If the latter, would you use CN or C3 bearings?


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