Output Shaft Coupling Hunter 28.5

[Simon Sexton]

Hey y’all,

My friend Max and I have been making great progress on our newly acquired 1987 Hunter 28.5 . The Yanmar 2gm onboard is seized, so we’ve been working patiently to slowly un-seize it. A looming issue is the steady drip coming from the plastic packing gland (stainless replacement on the way), as well as the heavily oxidized prop shaft coupling and output shaft coupling. I cannot, for the life of me, find a replacement part or trustworthy number for the output shaft coupling. Any help would be much appreciated. Thanks!

Simon Sexton ~ Youth Sailing Coordinator, Sea Star Base Galveston

 

[Tally Ho]

Are you looking for the shaft coupling? Or the transmission output flange.

I replaced the shaft coupling on my Yanmar 2GM20 with a coupling from Buck Algonquin…

Solid Couplings

General Propeller stocks the full line of Buck Algonquin manufactured solid style shaft transmission couplers for most marine transmissions. The couplers are cast from ductile iron and machined to SAE J755 specifications. Most of our couplers are machined with a universal bolthole pattern. We

www.generalpropeller.com

Just look for the Yanmar bolt circle of the correct shaft size.

If I were to do it all over again, I would use a split coupling, but the solid ones are OK.

Dang, that thing looks nasty!

Good luck,


Greg

 

[Simon Sexton]

Are you looking for the shaft coupling? Or the transmission output flange.

I replaced the shaft coupling on my Yanmar 2GM20 with a coupling from Buck Algonquin…

Solid Couplings

General Propeller stocks the full line of Buck Algonquin manufactured solid style shaft transmission couplers for most marine transmissions. The couplers are cast from ductile iron and machined to SAE J755 specifications. Most of our couplers are machined with a universal bolthole pattern. We

www.generalpropeller.com

Just look for the Yanmar bolt circle of the correct shaft size.

If I were to do it all over again, I would use a split coupling, but the solid ones are OK.

Dang, that thing looks nasty!

Good luck,


Greg

Good morning @Tally Ho ! The "output flange" is what I'm looking for (I've learned that almost everyone calls it something different). The part you attached to your post seems to be the prop shaft coupling; the part I'm looking for is the one behind it that's fastened to the transmission. Thanks for your help!

 

[Sailgunner]

You can find repalcement couplings at general propeller. You will need the shaft size and bolt hole dimensions. R&D Split Coupling 202-316
The next issue you will have is removing the old coupling. I had a puller made from a steel plate. Can send you pics if you like.

 

[jssailem]

If you are just trying to get by, then the shaft/transmission couplings are all you need.

Looking at the short image of the shaft, I suspect you want to put that on your list as well. If the shaft is compromised (as it appears to be), then you will need to look at the whole system right back to the prop.

Depends on how certain you want the boat to be ready for use and for how long. A challenged prop shaft failure is one that can sink a boat for an unprepared skipper.

 

[Tally Ho]

I have a Kanzaki KM2P transmission paired to my Yanmar 2GM20F.

the link below shows the transmission output shaft parts. #13 is what you are looking for I think (assuming you have the same tranny).

I haven’t found a US source…

Yanmar Shop - FIG 13. OUTPUT SHAFT Schematic

View detailed interactive schematics and parts lists for FIG 13. OUTPUT SHAFT at Yanmar Shop

yanmarshop.com

Greg

 

[heritage]

Is the oil in the picture from the transmission?

 

[Tally Ho]

And as @jssailem said, replace that shaft too…and probably the stuffing box while you are in there…and the strut bearing if the shaft is out!

I upgraded my shaft and coupling first, then replaced the stuffing box last year with a a Volvo Penta dripless seal…I really like it so far!

Here are some videos to give you some ideas…

And finally, here is link to the shaft seal install…

Volvo Penta Shaft Seal Install

youtu.be

Greg

 

[Simon Sexton]

If you are just trying to get by, then the shaft/transmission couplings are all you need.

Looking at the short image of the shaft, I suspect you want to put that on your list as well. If the shaft is compromised (as it appears to be), then you will need to look at the whole system right back to the prop.

Depends on how certain you want the boat to be ready for use and for how long. A challenged prop shaft failure is one that can sink a boat for an unprepared skipper.

Good morning @jssailem ! Great to hear from you. We aren't "trying to get by", but our wallets are tight and we are chipping away at the project one piece at a time. This weekend the boat will be hauled out here at work (we have a 5T crane) for a bottom cleaning, thru-hull inspection and packing gland replacement (I still can't believe the original is plastic...). We've got a dripless Stainless one arriving in the mail today, so the install will be complete tomorrow. Eventually, the boat will be hauled out at a local yard and on the hard for a while so we can complete a list of tasks during the "off season", which includes removing the prop shaft and inspecting/replacing everything that needs it. Thanks for your help!

 

[Simon Sexton]

Is the oil in the picture from the transmission?

Good morning @heritage ! The goopy mess down there does look a little concerning at first, but it's actually just residue buildup on the bilge paint from the dripping packing gland over the years. Thanks for the reply!

 

[Simon Sexton]

And as @jssailem said, replace that shaft too…and probably the stuffing box while you are in there…and the strut bearing if the shaft is out!

I upgraded my shaft and coupling first, then replaced the stuffing box last year with a a Volvo Penta dripless seal…I really like it so far!

Here are some videos to give you some ideas…

And finally, here is link to the shaft seal install…

Volvo Penta Shaft Seal Install

youtu.be

Greg

Hey @Tally Ho ! Thank you for the videos, I stayed up late last night watching them, and they're very helpful and informative. I'll be sure to refer to them as much as possible. Thank you!

 

[jssailem]

Sounds like a great project. It would be an interesting learning opportunity for local boat owners. Wonder if you could get a group together around the project.

 

[Simon Sexton]

Sounds like a great project. It would be an interesting learning opportunity for local boat owners. Wonder if you could get a group together around the project.

Thanks @jssailem ! It is definitely a learning experience; I've been around and sailed boats pretty much my entire life, but never had to practically rebuild one with this amount of damage. Thankfully, my friend and I are blessed with experienced coworkers and friends who are willing to chip in their time and knowledge to help us out. We've also had a lot of support from management here at SSBG because the boat used to belong to our founder, Capt. Charles Doolin. Can't wait to make more progress and get her sailing again...a video is coming later today with more details!

 

[smokey73]

Looks like you and Max and your friends have your work cut out for you. I am sure its a labor of love for you and your co-workers. Since the engine is seized I am assuming you can't really determine the condition of the transmission unless you knew that before the engine seized up.

With that in mind, I am not sure I'd tackle anything with the output flange, shaft flange, shaft and anything down the line just yet. Looking at the condition of the flanges, nuts and shaft it would seem reasonable it is really going to be a chore to even get the bolts to turn to disconnect the flanges. It is hard enough to do and to get the shaft flange off even if everything looks "good." I would imagine that you will need to somehow cut something to get the flanges separated and from there "project creep" rears its ugly head. I am sure you and your crew are aware of that but at roughly $226 plus shipping for the transmission output shaft alone to install on a transmission that may or may not need overhaul/replacement things could spiral out of control for this "simple" job very quickly. Even with "free labor" the parts cost alone might dictate a different approach like repower or replacement of the transmission, etc. Just saying.

 

[Simon Sexton]

Looks like you and Max and your friends have your work cut out for you. I am sure its a labor of love for you and your co-workers. Since the engine is seized I am assuming you can't really determine the condition of the transmission unless you knew that before the engine seized up.

With that in mind, I am not sure I'd tackle anything with the output flange, shaft flange, shaft and anything down the line just yet. Looking at the condition of the flanges, nuts and shaft it would seem reasonable it is really going to be a chore to even get the bolts to turn to disconnect the flanges. It is hard enough to do and to get the shaft flange off even if everything looks "good." I would imagine that you will need to somehow cut something to get the flanges separated and from there "project creep" rears its ugly head. I am sure you and your crew are aware of that but at roughly $226 plus shipping for the transmission output shaft alone to install on a transmission that may or may not need overhaul/replacement things could spiral out of control for this "simple" job very quickly. Even with "free labor" the parts cost alone might dictate a different approach like repower or replacement of the transmission, etc. Just saying.

Ahoy @smokey73 ! Very good points there, thanks so much for your reply. Re-powering the boat isn't out of the picture, but we want to try and do out best to save the engine and gear that is already there (fingers crossed). Finding a new or refurbished Yanmar 2gm isn't too difficult around here, and we even admitted to preferring a raw water cooled model rather than the current freshwater cooled engine. Time will tell...

 

[Ralph Johnstone]

and we even admitted to preferring a raw water cooled model rather than the current freshwater cooled engine.

Just had to ask what's your reasoning behind preferring raw water cooling ?

 

[Simon Sexton]

Just had to ask what's your reasoning behind preferring raw water cooling ?

@Ralph Johnstone it's just a preference of familiarity; the boats I grew up sailing on were all raw water cooled except for one (a custom built offshore catamaran with twin NorPros). The freshwater cooled system has its pros though. Another factor is cost for a new motor as far as our research could tell.