M5B Prop Shaft Housing - Factory Service Manual…

[Dotard69]

I’m needing to replace the prop shaft oil seal due to a minor leak.

I have Factory Manual…see attached page…it has no guidance on how to remove the shaft housing for the M5B. Just the 2.5/3.5 and 8+ HP…. In fact there are several sections in the manual where there is no guidance for the 5hp…. Note the factory manual I have is Part #: 003-21035-0, 9810 KC 2800 (those numbers are on the back page….). Is this the correct manual….?

Question I have is whether I can pull just the shaft housing off (once I get the thrust holder off…bigger issue as you can see from the pictures…) or does the shaft come out as too. On a Yamaha I used to have, the housing came off clean without the shaft needing to be pulled out…. The housing isn’t budging at all - despite PB Blaster and Liquid wrench soaking along the seams, which seem fairly clean.

 

[Dotard69]

UPDATE: Tried to edit message…just ahead of the Prop Thrust holder (between where the propp would sit and the holder)…there is this strange o-ring. Nowhere mentioned in the service manual nor any on-line parts. Diameter is same as the thrust holder…

 

[ahicks]

I'm pretty sure you'll be able to at least see the seal when you manage to get that prop thrust washer off. They are generally taper fit to the prop shaft so they don't rock around in use.

I would likely give that a few good whacks using something that will allow you to hit it squarely. Otherwise it's a pretty sure bet you'll be looking for that part as well. 1/2"x12" socket extension and a 2 lb sledge?

 

[pvanv]

The M5B is pretty old, so you may need to persuade the housing out. Yes, you need the housing out and pull the prop shaft fwd, then the seals can be driven out with a drift. May as well get a complete LU seal kit and do them all. Don't forget the 2 o-rings for the cam rod.

 

[Dotard69]

So after various coaxings I just gave up, lest I destroy the entire thing in frustration with my sledge hammer….I did a static pressure test at 6, 8 and 10 PSI (with oil removed of course…) and no leaks ping after sitting for 20 minutes, even after turning the drive shaft by hand. The oil wasn’t coffee cream colored, just a bit cloudy. It went from being in freezing temps for a few days to my warm 70ish degree basement…could that have caused the cloudiness..?

plan b is taking to local Tohatsu guy, but I know he won’t work on it as he don’t like working on small outboards…

and yes the engine is old, but still runs. No budget for a new SailPro though…I do like the redesign with new white color….

 

[Dotard69]

UPDATE…. HO LEE…. after going moderately crazy….
housing is out but destroyed in process….guess I’ll add up cost of parts…LU proper seemed reasonably unscathed…

 

[Sea Rider]

Out of curiosity, it's an old motor run in fresh or salted water to account for such visible lower leg deterioration ?

Happy Boating​

 

[Dotard69]

Out of curiosity, it's an old motor run in fresh or salted water to account for such visible lower leg deterioration ?

Happy Boating​

saltwater.

Note that some of what you see isn't all corrosion, it was me hacking the heck out of the housing section to get it out. sheared off the 2 ears for bolting to LU, and some of the lip where the prop sits i damaged during removal.... but im getting all new parts so didn't care...

i've only owned it since 2014. looks like $60 in parts will take care of this. and i've already installed a new water pump about 4 years ago....

 

[Sea Rider]

MOD EDIT - iBoats sells the parts that supports this forum.

Happy Boating​

 

[Dotard69]

MOD EDIT - iBoats sells the parts that supports this forum.

Happy Boating​

yep. mine is circa 1994/5, it came with the sailboat i purchased in 2014. Removed by Mod.

 

[Dotard69]

MOD EDIT - iBoats sells the parts that supports this forum.

Happy Boating​

I looked and they don’t carry the parts.