Saildrives

Manufacturer: Yanmar
Description: Saildrive Unit
Model: SD20
Manual: File:SD20 Operations Manual 2009.pdf
Parts catalog: File:SD20 Part Catalog.pdf
O-Ring parts diagram: File:SD20 O-rings Parts Diagram .pdf
Service Bulletin - Taper pin: File:SD20 Taper Pin Bulletin.pdf

Part Numbers
Saildrive seal replacement kit
196313-02591 Saildrive seal, oil prop shaft (Qty 2 per saildrive)
24321-000950 Saildrive rear cover O-ring (Qty 2 per saildrive)
24341-000125 O-Ring, drain plug (Qty 1 per saildrive)
196315-02880 Circlip, Needle 52 (optional to reposition seals)

Others
196420-02551 Rubber protector, saildrive leg
196420-02602 Saildrive, rear cover
196311-04060 Needle Bearing (supports propeller shaft, replace it needles fall out or are loose)
196440-02701 Bolt, Bracket (Split zinc bracket, flat head M6X18)
26453-100252 Bolt, M10X25 (Saildrive rear cover bolt)
196420-02530 Drain, M10 (Saildrive oil plug)

Notes:
Blown seals: The SD20 is susceptible to blowing the seals if the oil is filled too high. Many have added a vent line to the top of the filler cap. Without the vent, only fill the saildrive oil to the bottom of the dipstick

Sheared tapper pin repair: External Link

Oil specifications: 80W90W gear oil (API GL-4 or GL-5)
Oil capacity: 700ml
Oil change interval: Every 250 hours of operation or annually (whichever comes first)

Procedure to change oil in the water:

1. Using a pump with a small tube remove as much oil as possible
   
2. Refill oil to full capacity (bottom of dipstick)
3. Run engine 5 minutes
   
4. Using a pump with a small tube remove as much oil as possible
   
5. Refill oil to full capacity (bottom of dipstick)
   

(This will replace over 75% of the oil)

Outer diaphragm and secondary inner diaphragm
Replacement Guidelines: Inspect every 2 year and replace every 5 years
Common Practice: Monitor condition and test the water penetration sensor
Recommendations: Pacwest in San Diego does not recommend changing the diaphragms unless there is visible damage or water has penetrated the outer diaphragm. These diaphragm almost never fail. I have read this from other sources who make the same recommendation.

Propeller Shaft Grooves
It is an issue that they Gori propellers installed on a SD20 saildrive will form grooves over time which will result in sea water penetration. Periodic repositioning of the seals using shims allow longer life from the propeller shafts.

Grooves worn into the propeller shafts