B1 lower leaking lube around input shaft
 

I searched but can't find anything on this so I need some help from my boating buds. My B1 lower was leaking lube on the cavitation plate so I put new orings between the upper and lower; didn't help and same lube trail. Next time I pulled it apart, I spent plenty of time to see where the trail came from and where I might find the source. All surfaces seemed good and the best I can tell it is still leaking in the same place: the oring around the lower input shaft. The round plate/spacer that holds the oring, floats on shims and it seems recessed to deep to keep an adequate pressure on the oring to seal. I am guessing I need to shim it up to hold a sealing pressure. Is there a rule of thumb how much shim to add in this kind of situation? Is there a depth spec that I need to shim up to for adequate pressure on the oring without bottoming out the spacer on the lower unit? The oring is so deep in the groove that is leaks so what to do?
TIA

When the shim stack drops...why is that?
Why would oring tension press against the bearing preload?????? That seems unmanageable.
This setup looks very odd.

is the Tab washer installed under the shims,,then the shims,,then the spacer and O ring,,

Get with Clustergear, he knows his chit when it comes to drives. He is a good guy and might be able to walk you thru a fix.

If I had a Bravo issue today, I would be on the phone to him tomorrow.

Yes, that is the order of what is there. Drive works fine just leaks right there and the oring seems too deep in the recess which would have to be shims needed to push it up higher.

Yes, it is all there just as pictured. So if the shims under the tabbed washer are fine, I assume since the drive works fine, then the shims at #16 could increase to tighten up the oring, right?
The drive works very well and servicing has no fuzz on the magnet. Just has a very slow leak right at the oring.
The amount to bump up the shims can not exceed a crush interference I understand. I'm guessing I just need a slight move to make it seal. Is that right?

I put in a new oring and used silicone grease on it. The first time I just installed it without any close inspection thinking the oring just got too hard. When it still leaked I looked at the upper and lower very close. The paint is not even scratched in the recesses and nothing in the area of the oring made me suspicious. I did notice that the level of the oring in relation to the surface, was very low and comparing to the other orings in the area it was definitely lower. The shims are the only way to push the spacer up but like you said it adds to the preload. That just looks stupid to me. If the tabbed washer does not act as a stop for the bearing shims then all the shims affect that preload. Again that just seems stupid. Calling it like I see it. Due to the spacer being recessed it has to go up to make the oring seal. Just strange that I only noticed this now and it leaked now.
So let me ask: is a .005 or a 3 or 8 or 10 a safe gamble on a shim to make the oring seal?
What is the 101 grease comparable to? Can a comparable work or is the 101 grease just the best way for this to work? Is there sealing properties to this 101 grease? Is it silicone based?
I am just frustrated seeing something that seems so stupid with bearing preload tensioned by shims and an oring. The shims should be absolute to the bearing and not affected by anything else. Especially where running vibration can affect a seal that can allow water to compromise the drive. So hoakie! Definitely not one of Mercs shining moments there.

If it were mine I would take the lower completely apart and start over ,first check that the lower pinion gear is shimmed to the correct height,,be sure the correct bearings and races are installed on the vertical shaft,,,install the correct shims to get the correct rolling torque on the vertical shaft, when all these things are set correctly the spacer and o-ring should be at the correct height to seal the oil.,,

Allittle Ultra Black will seal you right up.

What he said. When the lower is assembled correctly the top of the retainer is a few thousandths above the lower housing. This represents the preload applied to the upper 2 bearings on the shaft.

First the pinion height is set by the shims under the lower cup then the preload is set by the shims above the tab washer. When the upper & lower are assembled the retainer is clamped flush. The o ring probably adds a little bit of preload but it is really only there to seal.

If the top of the retainer is exactly flush or below the surface for sure there is something wrong.

Update:
So a huge THANKS to Jeff Harris of Harris Performance!!! He knows tech spec details and can talk specifically to the design.
Preloading a bearing through an oring made no sense to me but the plate crushes between the upper and lower to set/hold the shim preload. I could follow that. #17 is called a spacer in the diagram but that is more functionally a centering plate for the lower input shaft and it is part of the shim buildup to set preload. So the bottom line on the plate/spacer is 1/2 to .001 above the deck of the lower. Somehow my plate was down .007. Just out of nowhere this drive starts leaking and this is why. Why it dropped .007 is still a mystery but it caused a leak.
I have another drive and the plate/spacers are different thicknesses and the shim stacks were different so between the two I was able to set my spacer to spec, between 1/2 and .001. We ran four days in Allatoona, slept on the boat and it has set where the sun would shine on the drives and build pressure to the point of a leak and still, no leak. The drive is quiet, no noise and nothing has changed but the leak is gone.
Happy Boating