Part of the Yanmar Operator Manuals.
Milky oil in a saildrive leg is the kind of find that ends a season, and the only honest answer to it is the inspection schedule Yanmar actually printed. That schedule lives in publication 0ASDM-G00101, the factory operation manual for the SD20, SD50 and SD50-4T sail-drives, matched at the factory to the 1GM10C, 2YM15, 3YM20, 3YM30 and the 3JH and 4JH series diesels.
With it you can fit and torque a propeller to the published figure instead of a guess (a guessed nut torque is how props leave the boat), fill the leg to the correct capacity, run the break-in properly, and work the cone clutch, diaphragm and anode intervals that keep water out of the gearcase.
It is an 86 page bookmarked PDF. Print the torque charts and the maintenance table, take them to the boat, and let them get oily.
What's Inside This Yanmar SD20, SD50, SD50-4T Manual
| System | Pages | Key Topics |
|---|---|---|
| Introduction | 5-6 | Sail-Drive Models, Engine Models, Engine and Sail-Drive Combinations |
| Safety | 7-12 | Safety Precautions (Before You Operate, During Operation and Maintenance) |
| Product Overview | 13-18 | Overview (Owner / Operator Responsibilities, New Sail-Drive Break-In, Dealer / Distributor Responsibilities, Component Identification, Galvanic Corrosion, Corrosion Control, Shore Power, Underwater Drive Coating) |
| Before You Operate | 19-28 | Propeller Selection (Recommended Propeller Size, Fitting a Fixed Propeller), Lubricating Oil (Filling with Lubricating Oil - SD20, SD50 and SD50-4T) |
| Sail-Drive Operation | 29-34 | Remote Control Device Check, Sd20, Sd50 / Sd50-4T, Engine Cooling Water (Sd20) |
| Periodic Maintenance | 35-56 | Tightening Fasteners, Torque Charts, Periodic Maintenance Table, When the Vessel Is Out of the Water, Perform the Following:, Periodic Maintenance Procedures |
| Specifications | 57-58 | Reduction Gear System, Direction of Rotation, Reduction Ratio, Lubricating Oil Capacity, Dry Weight, Remote-Control Device |
| System Diagrams | 59-86 | Maintenance Log |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| SD20 | ||
| Propeller Nut Tightening Torque, SD20 | 60 to 70 N·m (44 to 52 lb-ft) | p. 21 |
| Dry Weight, SD20 | 30 kg (66 lb) | p. 57 |
| Reduction Ratio (Ahead) | 2.64 | p. 57 |
| SD50, SD50-4T | ||
| Propeller Nut Tightening Torque (SD50, SD50-4T) | 80 to 100 N·m (59 to 74 lb-ft) | p. 21 |
| Lubricating Oil Capacity (Long-Reach Unit, Extension 100) | 2.45 L (2.6 qt) | p. 23 |
| All Models | ||
| Cone Clutch Inspection/Lapping Interval | Every 500 hours | p. 40 |
| Cone Clutch Replacement Interval | Every 2000 hours | p. 40 |
| Rubber Diaphragm Inspection Interval | Every Year | p. 40 |
| Rubber Diaphragm Replacement Interval | Every 5 Years | p. 40 |
| SD20, SD50, SD50-4T | ||
| Lubricating Oil Capacity (Standard Unit) | 2.2 L (2.3 qt) | p. 23 |
| SD50 | ||
| Dry Weight, SD50 | 39 kg (86 lb) | p. 57 |
| SD50-4T | ||
| Dry Weight, SD50-4T | 41 kg (90 lb) | p. 57 |
Yanmar SD20, SD50, SD50-4T Common Problems This Manual Covers
Cone clutch slipping in forward
SD50 and SD50-4T owners report the drive slipping under load, sometimes at modest hours. The manual schedules cone clutch inspection and lapping every 500 hours and replacement at 2000 hours, which is the maintenance most slipping drives never got.
Manual Section: Periodic Maintenance p. 35Milky oil in the leg
Emulsified lubricating oil means seawater is getting past the lower seals. The oil filling procedure and capacities (2.2 L for a standard unit) let you drain, refill and recheck so you can tell a one-off from an active leak.
Manual Section: Before You Operate p. 19Rubber diaphragm aging and water alarm
The diaphragms sealing the drive through the hull are the part that sinks boats when ignored. The manual calls for inspecting them every year and replacing them every 5 years, alongside the other out-of-water checks.
Manual Section: Periodic Maintenance p. 35Anode wasting away from galvanic corrosion
An aluminum drive leg in seawater is a sacrificial part unless the anode and bonding are right. The manual covers galvanic corrosion, corrosion control, shore power precautions and the underwater drive coating.
Manual Section: Product Overview p. 13Propeller nut loose or over-torqued
A propeller nut done by feel either backs off or strips. The manual gives the fitting procedure for a fixed propeller and the nut torque: 60 to 70 N·m for the SD20, 80 to 100 N·m for the SD50 and SD50-4T.
Manual Section: Before You Operate p. 19Shift lever stiff or vague
A lever that will not drop cleanly into ahead, astern or neutral points to linkage adjustment or clutch wear. The remote control device check and the shifting procedures for each model are the place to start before opening the drive.
Manual Section: Sail-Drive Operation p. 29Frequently Asked Questions
Which sail-drive and engine models does this manual cover?
It covers the Yanmar SD20, SD50 and SD50-4T sail-drives, and the Introduction lists the factory engine combinations: 1GM10C, 2YM15, 3YM20, 3YM30, 3JH4CE, 3JH5CE, 4JH4ACE, 4JH5CE and 4JH4-TCE. p. 5
What is the propeller nut torque spec for the Yanmar SD20, SD50, SD50-4T sail drives?
The propeller fitting procedure gives 60 to 70 N·m (44 to 52 lb-ft) for the SD20 and 80 to 100 N·m (59 to 74 lb-ft) for the SD50 and SD50-4T. p. 19
How much oil does the sail-drive hold?
The lubricating oil section lists 2.2 L (2.3 qt) for the standard unit on all three drives, and 2.45 L (2.6 qt) for the long-reach (Extension 100) SD50 and SD50-4T. The filling procedure covers all models. p. 19
How do I get the manual after purchase?
It is a digital download. After checkout you get the complete PDF immediately, in English, ready to save to your devices or print. Nothing is shipped.
How is this Yanmar SD20 Operation Manual delivered?
Immediate download of the complete 86-page searchable Operation Manual. Access it on any device, from a laptop at your desk to a phone in the field.
Can I print specific sections of this manual?
Absolutely. No DRM or copy protection. Print the whole manual or just the pages you need. Any home or office printer works.
Are there wiring harness diagrams in this Yanmar SD20 manual?
Included. The Yanmar SD20, SD50, SD50-4T Operation Manual provides a wiring diagram for the electrical system.
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