Cruisers Forum

  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
Thread Tools Search this Thread Rate Thread Display Modes
Old 23-07-2018, 04:46   #1
Registered User

Join Date: Apr 2013
Location: Manly, Qld, Aust
Boat: Fusion 40
Posts: 145
Yanmar SD20 Prop Shaft Seals

I have replace the seals each slipping for the past 3 times as the oil was milky. This time the oil was good so I thought if its not broke...... However you guessed it 2 mths after slipping the stbd leg is contaminated. I have read extensively in these forums on the solutions and have installed a header tank as an interim measure to manage the problem and this appears to work well.

However thinking about the issue I'd like to float some ideas past the brains trust and really would like to hear from anyone who may have experimented along these lines.

Mod #1: Shift one of the spacers between the seals to the outer most position behind the outer seal so the seal runs on a fresh surface.

I can see no real reason for these spacers to be there and doubt the spacing between these seals is critical. I have noticed the problem seal seems to be the outer seal that wears a groove in the shaft possibly due to calcium or other particle buildup where the seawater interfaces with the seal.

Mod#2: Reverse the inner seal so that the seal is more effective at preventing water ingress rather than the oil egress.

This could allow some oil to leach from the drive, fill the annular space and lubricate the outer seal thus minimising the scouring of the shaft from the outer seal. Would a lot of oil leach from the drive if this were done.

jacktheflyer is offline   Reply With Quote
Old 23-07-2018, 16:53   #2
Registered User

Join Date: Mar 2009
Location: Southern Chesapeake Bay
Boat: Norseman 430, Jabberwock
Posts: 1,012
Re: Yanmar SD20 Prop Shaft Seals

I installed my header tanks close to 15 years ago, and haven't looked back.
ggray is offline   Reply With Quote
Old 23-07-2018, 18:54   #3
Registered User
Dulcesuenos's Avatar

Join Date: Dec 2010
Location: Western Caribbean
Boat: 38/41 Fountains pajot
Posts: 3,060
Images: 4
Re: Yanmar SD20 Prop Shaft Seals

We've resealed ours 3 times, never had moisture issue, have repositioned seals but wouldn't change the recommended direction the seals face. We did smooth the shaft a tiny bit with emery cloth and have done the header tank conversion. Drives are 1995 sd20s.
Dulcesuenos is offline   Reply With Quote

seals, shaft seal, yanmar

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Yanmar SD20 Saildrive Oil Seals - Water in Drive matrix Propellers & Drive Systems 54 29-04-2020 02:39
Yanmar SD20 prop shaft stub fracture Somadoc Propellers & Drive Systems 8 19-06-2019 10:36
Speedi Sleeve for Yanmar SD20 prop shaft tunnelvision Propellers & Drive Systems 1 19-08-2016 23:39
shaft seals, lip seals,..oh my sailorboy1 Propellers & Drive Systems 50 04-03-2013 19:50
Prop Shaft Seals bcguy Product or Service Reviews & Evaluations 1 06-08-2007 15:47

Advertise Here

All times are GMT -7. The time now is 16:16.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.