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B1 lower leaking lube around input shaft

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B1 lower leaking lube around input shaft

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Old 07-27-2019, 08:27 PM
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Default 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?
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Old 07-28-2019, 10:01 PM
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The shims are there to set the pinion bearing preload. You ready just can’t add more.
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Old 07-29-2019, 11:16 AM
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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.
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Old 07-29-2019, 02:23 PM
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is the Tab washer installed under the shims,,then the shims,,then the spacer and O ring,,
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Old 07-29-2019, 04:01 PM
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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.
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Old 07-29-2019, 05:36 PM
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Originally Posted by aquaforce View Post
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.
when setting pinion depth and preload there is a plate (tool) that bolts on to lower that simulates as if the upper was bolted to lower. Hopes this link works it a picture of how the spacer and shim go https://www.mercruiserparts.com/bam/...30968/5398/110
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Old 07-30-2019, 07:37 PM
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Originally Posted by 253 View Post
is the Tab washer installed under the shims,,then the shims,,then the spacer and O ring,,
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.
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Old 07-30-2019, 07:44 PM
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Originally Posted by Clustergear View Post

when setting pinion depth and preload there is a plate (tool) that bolts on to lower that simulates as if the upper was bolted to lower. Hopes this link works it a picture of how the spacer and shim go https://www.mercruiserparts.com/bam/...30968/5398/110
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?
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Old 07-30-2019, 10:00 PM
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If you add more shims it will increase the preload on pinion bearing, which may make them run hotter and wear faster. Look close at case where o ring goes, does it have any marks ( like someone prayed the o ring out or the metal spacer #17 and scored case). Check upper case & spacer (#17) for marks too. When I put the half’s together I use Merc 101 grease on the o rings to help seal. This area is usually not a problem area to seal when using new o ring
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Old 07-31-2019, 07:40 PM
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Originally Posted by Clustergear View Post
If you add more shims it will increase the preload on pinion bearing, which may make them run hotter and wear faster. Look close at case where o ring goes, does it have any marks ( like someone prayed the o ring out or the metal spacer #17 and scored case). Check upper case & spacer (#17) for marks too. When I put the half’s together I use Merc 101 grease on the o rings to help seal. This area is usually not a problem area to seal when using new o ring

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.
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