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Tohatsu MFS25B / MFS30B EFI (2006) service guide

Oil, gear oil, spark plugs and the service schedule for the Tohatsu MFS25B / MFS30B EFI (2006) (25 to 30 hp, four-stroke), from the factory service manual, plus how we service it in Hawaiʻi.

Models covered: MFS25B and MFS30B, types MF, EF, EP, MFG, EFG, EPG, EFT, EPT, S / L / UL transom. 4-stroke 3-cylinder, 526 cm³ (32.09 cu in), 61 x 60 mm, SOHC, electronic fuel injection, CD ignition.

Quick answers

How much oil does a Tohatsu MFS25B / MFS30B EFI take?
1.8 L with filter; 1.6 L without filter; fill to the upper dipstick mark.
What engine oil does a Tohatsu MFS25B / MFS30B EFI use?
4-stroke engine oil, API SE, SF, SG, SH, SJ or SL; SAE 10W-30 or 10W-40; NMMA FC-W certified 10W-30.
What gear oil does a Tohatsu MFS25B / MFS30B EFI use, and how much?
Hypoid gear oil, API GL-5, SAE #90. Quantity: 350 cm³ (11.8 fl oz); fill from the lower plug hole until oil comes out the upper hole.
What spark plug does a Tohatsu MFS25B / MFS30B EFI use?
NGK DCPR6E. Gap: 0.8 to 0.9 mm (0.032 to 0.035 in); limit 1.2 mm (0.047 in).
How often should a Tohatsu MFS25B / MFS30B EFI be serviced?
The factory schedule lists: Initial 20 hours or 1 month; Every 50 hours or 3 months; Every 100 hours or 6 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 Tohatsu MFS25B / MFS30B EFI?
The factory schedule says to inspect it at 50 hours and 100 hours. 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 Tohatsu MFS25B / MFS30B EFI?
850 ± 30 r/min in neutral; trolling 850 ± 30 r/min.
What is the propeller nut torque on a Tohatsu MFS25B / MFS30B EFI?
25 N·m (18 lb·ft) [2.5 kgf·m], then line up a groove and fit the split pin.

Maintenance specs

Engine oil4-stroke engine oil, API SE, SF, SG, SH, SJ or SL; SAE 10W-30 or 10W-40; NMMA FC-W certified 10W-30
Engine oil quantity1.8 L with filter; 1.6 L without filter; fill to the upper dipstick mark
Oil filter18 N·m (13 lb·ft) [1.8 kgf·m] with oil filter wrench P/N 3AC-99090-0; oil the O-ring; change 5 minutes or more after stopping
Engine oil drain bolt24 N·m (17 lb·ft) [2.4 kgf·m], M14 x 1.5; oil the washer
Gear oilHypoid gear oil, API GL-5, SAE #90
Gear oil quantity350 cm³ (11.8 fl oz); fill from the lower plug hole until oil comes out the upper hole
Gear oil plugsNew gaskets; attach the upper plug first.
Gear case leak test0.069 MPa (10 psi) [0.7 kgf/cm²]
Spark plugNGK DCPR6E
Spark plug gap0.8 to 0.9 mm (0.032 to 0.035 in); limit 1.2 mm (0.047 in)
Spark plug torque18 N·m (13 lb·ft) [1.8 kgf·m]
Idle speed850 ± 30 r/min in neutral; trolling 850 ± 30 r/min
ThermostatStarts opening 60 ± 1.5 °C (140 ± 3 °F); lift 3.0 mm (0.118 in) or more at 75 °C (167 °F); cover bolt 6 N·m (4 lb·ft) [0.6 kgf·m], new gasket
Propeller nut25 N·m (18 lb·ft) [2.5 kgf·m], then line up a groove and fit the split pin
Valve clearance, coldIN 0.15 ± 0.02 mm (0.006 ± 0.001 in); EX 0.20 ± 0.02 mm (0.008 ± 0.001 in); lock nut 7 N·m (5 lb·ft) [0.7 kgf·m]
Timing beltInspect for cracks, damage and wear; replace if necessary (no deflection spec). Belt tensioner bolt 27 N·m (20 lb·ft) [2.7 kgf·m].

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 drain plug gasket, gear case oil, gear case plug gaskets, propeller cotter pin

    Check: spark plugs, fuel filter

  2. Every 50 hours or 3 months

    Replace: gear case plug gaskets, propeller cotter pin

    Check: fuel filter, gear case oil, water pump impeller, 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: spark plugs, fuel filter, water pump impeller, anodes

  4. Every 200 hours or 1 year (our Hawai‘i yearly service) Hawai‘i

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

    Check: spark plugs, fuel filter, 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: Tohatsu service manual 25/30 2006, MFS25B/30B. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.

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