Yamaha F20A / F25A / F25X (498 cm³) service guide
Oil, gear oil, spark plugs and the service schedule for the Yamaha F20A / F25A / F25X (498 cm³) (20 to 25 hp, four-stroke), from the factory service manual, plus how we service it in Hawaiʻi.
Models covered: F20AMH, F20AEH, F20AE, F20AET and F25AMH (F25MH), F25AEH (F25EH), F25AEHT (F25TH), F25AE (F25ER), F25AET (F25TR) four-strokes: 2 cylinder OHC, 498 cm³ (30.4 cu in), 65.0 x 75.0 mm, one carburetor. Approved model code 65W for all of them. A different engine from the 362 cm³ F15 / F20 (6AG / 6AH).
Quick answers
- How much oil does a Yamaha F20A / F25A / F25X take?
- 1.7 L (1.80 US qt, 1.50 Imp qt) without filter; 1.9 L (2.01 US qt, 1.67 Imp qt) with filter.
- What engine oil does a Yamaha F20A / F25A / F25X use?
- 4-stroke engine oil, API SE, SF, SG or SH, SAE 10W-30, 10W-40 or 20W-40.
- What gear oil does a Yamaha F20A / F25A / F25X use, and how much?
- GEAR CASE LUBE (USA) or hypoid gear oil, SAE 90. Quantity: 320 cm³ (10.8 US oz, 11.3 Imp oz); fill through the drain hole until it overflows from the check hole.
- What spark plug does a Yamaha F20A / F25A / F25X use?
- DPR6EA-9, qty 2. Gap: 0.9 to 1.0 mm (0.035 to 0.039 in).
- How often should a Yamaha F20A / F25A / F25X be serviced?
- The factory schedule lists: Initial 10 hours (break-in); Every 50 hours (3 months); Every 100 hours (6 months); Every 200 hours (1 year). 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 Yamaha F20A / F25A / F25X?
- The factory schedule gives no replacement interval. In Hawaiʻi's warm salt water we replace it every 200 hours or 1 year, whichever comes first, because a worn impeller is the most common cause of overheating.
- What is the idle speed of a Yamaha F20A / F25A / F25X?
- 925 ± 50 r/min; trolling speed 820 ± 50 r/min.
- What is the propeller nut torque on a Yamaha F20A / F25A / F25X?
- 34.4 N·m (3.5 m·kg, 25.3 ft·lb).
Maintenance specs
| Engine oil | 4-stroke engine oil, API SE, SF, SG or SH, SAE 10W-30, 10W-40 or 20W-40 |
|---|---|
| Engine oil quantity | 1.7 L (1.80 US qt, 1.50 Imp qt) without filter; 1.9 L (2.01 US qt, 1.67 Imp qt) with filter |
| Oil filter cartridge | 17.5 N·m (1.8 m·kg, 12.9 ft·lb) with oil filter wrench YU-38411 / 90890-01426; oil the rubber seal and start it by hand |
| Engine oil drain bolt | 27.0 N·m (2.7 m·kg, 19.9 ft·lb) |
| Gear oil | GEAR CASE LUBE (USA) or hypoid gear oil, SAE 90 |
| Gear oil quantity | 320 cm³ (10.8 US oz, 11.3 Imp oz); fill through the drain hole until it overflows from the check hole |
| Gear oil drain and check screws | Install the check screw first, then the drain screw |
| Lower unit holding pressure | 100 kPa (1.0 kg/cm², 14.2 psi) at the oil level check hole, must hold 10 seconds; do not over pressurize |
| Spark plug | DPR6EA-9, qty 2 |
| Spark plug gap | 0.9 to 1.0 mm (0.035 to 0.039 in) |
| Spark plug torque (M12) | 17.2 N·m (1.7 m·kg, 12.6 ft·lb) |
| Idle speed | 925 ± 50 r/min; trolling speed 820 ± 50 r/min |
| Thermostat | Opens at 60 °C (140 °F); fully open at 70 °C (158 °F); valve lift 3 mm (0.12 in) |
| Propeller nut (M16) | 34.4 N·m (3.5 m·kg, 25.3 ft·lb) |
| Power trim and tilt fluid (PTT models) | ATF Dexron II; PTT fluid level check bolt 7 N·m (0.7 m·kg, 5.1 ft·lb) |
| Valve clearance, cold | IN 0.2 ± 0.05 mm (0.008 ± 0.002 in); EX 0.3 ± 0.05 mm (0.012 ± 0.002 in) |
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.
Initial 10 hours (break-in)
Replace: engine oil, oil drain plug gasket, gear case oil, gear case plug gaskets
Check: spark plugs, fuel filter
Every 50 hours (3 months)
Replace: gear case plug gaskets, propeller cotter pin
Check: spark plugs, fuel filter
Every 100 hours (6 months)
Replace: engine oil, oil drain plug gasket, gear case oil, gear case plug gaskets, propeller cotter pin
Check: spark plugs, fuel filter, thermostat, anodes
Every 200 hours (1 year)
Replace: engine oil, oil filter, oil drain plug gasket, gear case oil, gear case plug gaskets, propeller cotter pin, water pump impeller
Check: spark plugs, fuel filter, thermostat, anodes
We replace the water pump impeller at every service from 200 hours up, which can be sooner than the factory schedule, because of Hawaiʻi’s warm salt water.
Source: Yamaha F20A, F25A service manual. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.