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2006 BF50D shift shaft seal

D

domf

New member
Doing impeller kit and noticed some degradation of this shift shaft seal. Zero water in gearcase oil. Just looks like the really fine edge of this rubber is tearing. From what I can find online of similar models, seems like a pain to replace. Can anyone confirm? And would you guys agree to leave it?
Thanks!
 

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Dangar marine had a good video of the process for a BF30 shift shaft seal. He had to slide hammer the whole shaft out and break the pins. I'd rather not tackle that on my own. However, the BF50D diagram looks a bit different. I'm wondering if I were to free up the stuck cover (#14), if then the worn seal (#29) can be removed by sliding it up the gear select rod, and replaced? OR if it will still require removal of the entire rod via slide hammer.
Thanks again for looking!
 

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As long as you're in there you should replace it if its bad.It looks like you can remove the 4 bolts on the cover,remove it,pry out the seal and replace it.I'm not a Honda mechanic but it looks like a easy repair.
 
That seal is a pretty easy project. Getting that cover up and out of the case is the hardest part of the job, and in my experience will demand the most patience. It needs to be pried straight up (carefully, or you'll need one of those too!). I generally use progressively larger screw drivers. There is NO issue sliding the cover (w/installed seal) up over the shift shaft. When ordering the seal, make sure you order the O-ring that goes on the cover to seal it to the lower unit (see #31 in above diagram). You'll want to replace that as part of the seal replacement job.
 
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So that was an absolute bear. Glad I did it- it was really jammed up in there. Cleaned it up and gave a light coating of POR-15 to the weathered areas.
Take a look at the loss of material below the water pump. Luckily this is still covered by the cup underneath the base plate.
So, for anyone with this style lower unit. I'd say to keep up with maintenance on that gear select cover before it welds itself in there like mine did. Lot of torching and banging like a caveman.
Flushed the gearbox from the top-down because there was no way to avoid some particles dropping into the bearing below the water pump.
Thanks for the help
 

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Wowee! That's a new one on me! If you have that kind of corrosion going on, wait until you try to r&r the prop shaft bearing carrier - to replace the prop shaft seals for instance! These are pretty well known to split the case (yes the MAIN lower unit/case!) on either side due corrosion build up between the bearing carrier and the lower unit/case. Crack will run parallel to the prop shaft. That'll require a skilled welder to repair..... Manual says you're supposed to remove these (the bearing carriers) every couple of years for a thorough cleaning of the affected areas - but I've never spoken with anyone that knows anything about that. ALL seem to learn the hard way - myself included... I can offer one tip. That locking ring that holds the bearing carrier in place? Don't even try to unscrew it. Drill a couple of holes through it about 3/4" apart (I do this down near the bottom), then break the 3/4" section out. THAT will allow the easy removal of the nut. THEN the struggle to get the bearing carrier out begins..... To reassemble, clearly those threads will be in dire need of cleaning. I use a small stiff wire wheel chucked in a drill for that. Have a new ring nut handy, and work on the threads until that new ring will screw in by hand. That's actually not as hard as it sounds.... -Al
 
Maybe that'll be a next winter project. Does that involve removing the 2 screws at 6 and 12 o'clock to the prop, then putting some sort of puller jaws down behind the prop shaft?
 
My bad. I'm working on/thinking of the older generation lower unit - that was basically a Merc. design.

Though I haven't seen on of these crack (yet), probably still not a bad idea to pull that bearing carrier - a MUCH easier project on the newer style. Yup, you can get a puller involved on that one...
 
Thanks for the photos and update. Is this outboard mostly used in salt water? Just curious.

I'd be very cautious about using a puller on that propshaft holder. Don't grab it by the mount bolt ears whatever you do! I can't remember if there are cutaways in the flange for pulling but, if there are, that's what you'll want to use for purchase.

I've had good luck pulling that type of propshaft holder using a pipe wrench or large slip joint pliers to just twist them back and forth a little while gently prying. Use a rag in the jaws to prevent the teeth from biting in. I don't think I ever used a puller on ones I did. Most of the ones I've done came out very easily. But those were all fresh water use only.

For a couple that were resistant to twisting, I used a small chisel with an exaggerated taper ground in it and sharp edge. Tap (gently!) and wedge in between the flange and seat. A little on one side, a little on the other until it moves outward a bit and will twist a little. You could also use a thin piece (1/8") of scrap steel and sharpen it if you don't want to sacrifice a chisel.

Good luck.
 
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Nice, thanks for that. I will refer back to this next year. There are cutaways in the flange- one on each side.
Yep, ~550 hours in the salt from previous owner, primarily slipped I believe. Rest of the outboard seems to be in pretty nice shape for it's age- 2007ish? But the lower unit seems to have taken the most salt abuse.
 
Well, your experience might be a bit tougher than mine with the salt. But, hopefully not. I'll never understand why people leave their outboards on slipped boats not tilted up out of the water but they do. I realize that in cold climates some are worried about ice forming in the hub but I would think that's easily dealt with using maybe a sponge, a glad bag and a bungee cord.
A pity what some of those lowers look like after constant submersion.
 
Re: a slipped salt water motor, you're sort damned if you don't tilt the motor up and out and damned if you do! Doesn't take much imagination to consider what happens when you DON'T tilt it up, but if you do, consider all the internal cooling passages within the motor that are not going to be drained. Those passages depend on the motor being vertical to drain properly. Now add a little sediment to the undrained water, that can settle out while the motor isn't being run, and last, consider that sediment is eventually going to get hard as a rock during repeated cooling heating sessions. So in my mind, as somebody with a LOT of experience fixing dead Honda motors (salties), the question becomes would you rather replace the lower, or the head/short block? Best plan is to trailer it, or keep it on a hoist, with the motor stored in the vertical position.... -Al
 
Went and pulled the prop shaft bearing holder while I was at it. It sucked. Just like the shift shaft cover, I had to destroy the flange in the process. Almost had nothing left to hit by the time it finally came free. In the process, I failed to take note of orientation of the 2 prop shaft seals. The ones below the water pump housing were both flat side to the oil. How about the prop shaft seals? And does anyone have a shop manual that actually shows these things? Can't seem to find one. BF50D. Thanks again!
 
I generally install so the flat sides face each other - but I would have done the same under the pump - so I would back that up with some confirmation somewhere is possible.....

Did you find corrosion buildup between the bearing carrier and the main housing?
 
It was seized up at the o-ring mating surface at the back end of the carrier. Wasn't really bad at the lip of the flange. It was just set ridiculously tight in there. And the fins of the carrier leave VERY small openings, so my cheap harbor freight 2 jaw puller was useless. Nothing to purchase on. I'm sure there are better pullers that can grab a hold of the "step" on the center ring of the carrier (the inner cup immediately hugging the prop shaft), but I didn't have anything like that. So I just beat on it like a neanderthal again LOL. Would not recommend. Glad that's behind me. And regarding the seals, ya- I'm not sure. I've read mixed opinions on orientation!
 
Too bad the thing was so hung up in there. Probably has much to do with the salt water.

The parts page depiction shows the seals "stacked" with flat sides facing rearward/outward. I believe that is probably what you'll find in the shop manual. See item 23 in the link below. Sorry, I don't have access to the SI for the 50D.

https://www.boats.net/catalog/honda...-bbej-1000001-to-bbej-1099999/propeller-shaft

That would be for maximum gear oil retention. I believe it's due to the pressure build inside the case as it heats up being more forceful than the vacuum created as it cools. But....I have never done the math on that. Just assuming their engineers did. I do have extensive background with stacked seals in hubs though and that is how they are installed as a general rule.

Having said that, I know many will install them facing each other to eliminate the possibility of water intrusion. I wouldn't necessarily argue with doing that. If installed with care and prelubed the result, in either case, will be a sealed unit as long as the shaft surfaces where the lips ride are clean and unscored and the boretite compound on the seal shell isn't marred or chipped. The seals are small enough that getting them in the bore squarely shouldn't be too difficult but I might consider having an extra on hand in case I boogered one up. It happens...to me anyway.

Good luck.
 
jgmo said:
Too bad the thing was so hung up in there. Probably has much to do with the salt water. The parts page depiction shows the seals "stacked" with flat sides facing rearward/outward. I believe that is probably what you'll find in the shop manual. See item 23 in the link below. Sorry, I don't have access to the SI for the 50D. https://www.boats.net/catalog/honda...-bbej-1000001-to-bbej-1099999/propeller-shaft That would be for maximum gear oil retention. I believe it's due to the pressure build inside the case as it heats up being more forceful than the vacuum created as it cools. But....I have never done the math on that. Just assuming their engineers did. I do have extensive background with stacked seals in hubs though and that is how they are installed as a general rule. Having said that, I know many will install them facing each other to eliminate the possibility of water intrusion. I wouldn't necessarily argue with doing that. If installed with care and prelubed the result, in either case, will be a sealed unit as long as the shaft surfaces where the lips ride are clean and unscored and the boretite compound on the seal shell isn't marred or chipped. The seals are small enough that getting them in the bore squarely shouldn't be too difficult but I might consider having an extra on hand in case I boogered one up. It happens...to me anyway. Good luck.
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This does make sense. I'm pretty certain my prop shaft seals were flat sides "back to back" and I'll probably reinstall that way. But what could the reasoning be for my impeller seals both being flat side down toward oil? I'm trying to decide if I reinstall them that way or if I go "back to back" there too. And the shift shaft seal was also flat side down toward oil but the boats.net parts diagram seems to show flat side up toward water. AND the cup of that shift shaft seal was worn to a wisp. I might be overthinking this, but I wish I could find a clear graphic or instructions from a shop manual if anyone has access to one!!!
 
I KNOW the outer prop shaft seal, from looking at hundreds of them on all sorts of outboards for the last hundred years or so, will normally have the lip facing the prop. That's how they're so easily torn up with fishing line, which is why you inspect them AT LEAST annually. Bonus is it allows you to get some grease on the prop shaft to avoid having a prop hub seize to the prop shaft at the same time. That's a battle that can get ugly fast.....

Interesting to hear regarding the corrosion build up on the carrier. I would have thought/hoped that would have been dealt with after their experience with the older (Merc.) style case. Thanks for that info... -Al
 
I don't know about the 50, but my BF20D manual shows the flat of the propshaft seal facing toward the prop, open end inward to oil. It also shows the waterpump housing mainshaft seal installed with the flat toward the engine (or up), open end down toward oil.

But they are both single seals with double lips. Not 2 separate seals stacked together as your 50D has on the propshaft.

It also seems to me, from looking at their design, that they would work if installed the other way around. The only reason I see for installing them as prescribed in my manual is to accommodate the use of the recommended driver and seal removal tools. Because, the seal lips would contact the shaft in the exact same way in either case if installed squarely and at the proper depth.

The attachment feature (among others) of this site is "jumbled" and unworkable using my phone or I would upload the manual graphics for you to look at. (haven't replaced my laptop). Maybe the upcoming update here will fix that soon though.

Not trying to confuse you....just geeking out a bit. Seals, seals and MO seals! ;>)
 
@jgmo @Alan Hicks one more question for you guys! Got it back together and running in the bucket. Water level happened to be at a perfect place to allow me to see these streams coming out of the 4 holes in the lower leg. 2 on each side near the transom side lower leg mounting bolts.

Have I just never noticed that? Or maybe with the brand new impeller there is more pressure down there and excess is being bled off that wasn’t before?

Or should I drop the leg and make sure that grommet that connects the pick up tube didn’t get shifted during install?

Water is still coming out if the tell tale

Thanks again!
 
So you would expect to see water under pressure shooting out of these holes at idle like mini tell tales? I think I normally have water level in the bucket higher than these holes, so maybe its always been this way and I just haven’t noticed?
 
Many of the engines I see have some or all of those holes plugged by sand/crud build up. Clearing them is part of replacing a pump for me.
 
Gotchya. Ran it again, it's hot water coming out of those holes. So I guess that answers my concern... it's not a bad fitment of the water tube pick up bushing. It's just water coming down from the head after cycling through. I was worried I was losing pressure of water coming up out of the pump.

Okay, enough fixing things and worrying for now. Time to run this thing

Thanks again
 
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