Suzuki DF40 / DF50 service guide

Quick answers

How much oil does a Suzuki DF40 / DF50 take?

2.2 L (2.3/1.9 US/Imp. qt) oil change only; 2.4 L (2.5/2.1 US/Imp. qt) with filter change.

What engine oil does a Suzuki DF40 / DF50 use?

API SE, SF, SG, SH or SJ, SAE 10W-40.

What gear oil does a Suzuki DF40 / DF50 use, and how much?

Suzuki Outboard Motor Gear Oil (SAE #90 hypoid gear oil). Quantity: 610 ml (20.6/21.5 US/Imp. oz); fill through the drain hole until it flows from the level hole.

What spark plug does a Suzuki DF40 / DF50 use?

NGK DCPR6E, qty 3.

How often should a Suzuki DF40 / DF50 be serviced?

The factory schedule lists: Initial 20 hours or 1 month; Every 50 hours or 3 months; Every 100 hours or 6 months; Every 200 hours or 12 months. In Hawaiʻi's salt water we do a full yearly service every 200 hours or 1 year, whichever comes first, and a new engine needs its first (break-in) service.

When should the water pump impeller be replaced on a Suzuki DF40 / DF50?

The factory schedule says to replace it at 200 hours, and we follow that. In any case we never let it go longer than a year in Hawaiʻi's salt water.

What is the idle speed of a Suzuki DF40 / DF50?

850 ± 50 r/min, in gear about 850; procedure: 800 to 900 r/min no load, engine warm.

What is the propeller nut torque on a Suzuki DF40 / DF50?

55 N·m (5.5 kg-m, 40.0 lb-ft); new cotter pin, bent over.

Maintenance specs

Engine oil	API SE, SF, SG, SH or SJ, SAE 10W-40
Engine oil quantity	2.2 L (2.3/1.9 US/Imp. qt) oil change only; 2.4 L (2.5/2.1 US/Imp. qt) with filter change
Engine oil filter	Oil the O-ring, hand tight until it touches, then 3/4 turn with the filter wrench: 14 N·m (1.4 kg-m, 10.0 lb-ft)
Engine oil drain plug	13 N·m (1.3 kg-m, 9.5 lb-ft), new gasket every time
Gear oil	Suzuki Outboard Motor Gear Oil (SAE #90 hypoid gear oil)
Gear oil quantity	610 ml (20.6/21.5 US/Imp. oz); fill through the drain hole until it flows from the level hole
Gear oil drain and level plugs	13 N·m (1.3 kg-m, 9.5 lb-ft), new gaskets
Gearcase leak test	100 kPa (1.0 kg/cm², 14.2 psi) through the oil level hole, turning the shafts; start at 0.2 to 0.4 kg/cm² (2.8 to 5.7 psi). Do not exceed 110 kPa (1.1 kg/cm², 15.6 psi)
Spark plug	NGK DCPR6E, qty 3
Idle speed	850 ± 50 r/min, in gear about 850; procedure: 800 to 900 r/min no load, engine warm
Thermostat operating temperature	58 to 62 °C (136 to 144 °F) for the 2005 and 2007 models. Check the model year
Anodes	Replace when 2/3 is gone; never paint; cover the anode bolt with Suzuki Silicone Seal.
Propeller nut	55 N·m (5.5 kg-m, 40.0 lb-ft); new cotter pin, bent over
Power trim and tilt fluid	Dexron automatic transmission fluid or equivalent; check tilted full up with the manual tilt lock lever down: full when oil shows at the filler plug. Do not mix fluid types
Tappet clearance, cold	IN and EX 0.18 to 0.24 mm (0.007 to 0.009 in); shim type. Turn the crankshaft clockwise only. Camshaft housing bolts 10 N·m (1.0 kg-m, 7.2 lb-ft)

Service schedule

The factory maintenance intervals, with what is replaced and what is checked at each. Rows marked Hawaiʻi are our shop's yearly service for salt water use.

1. Initial 20 hours or 1 month

   Replace: engine oil, oil filter, oil drain plug gasket, gear case oil, gear case plug gaskets, propeller cotter pin

2. Every 50 hours or 3 months

   Replace: gear case plug gaskets

   Check: fuel filter, anodes

3. Every 100 hours or 6 months

   Replace: engine oil, oil drain plug gasket, gear case oil, gear case plug gaskets, propeller cotter pin

   Check: fuel filter, anodes

4. Every 200 hours or 12 months

   Replace: engine oil, oil filter, oil drain plug gasket, spark plugs, gear case oil, gear case plug gaskets, propeller cotter pin, water pump impeller

   Check: fuel filter, anodes

Source: Suzuki DF40/50 service manual; Suzuki DF40/50 service manual, 99500-87J03-01E. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.