Tohatsu MFS 2 / 2.5 / 3.5 (A and B) service guide

Quick answers

How much oil does a Tohatsu MFS 2 / 2.5 / 3.5 take?

300 cm³ (10 fl oz) to the upper (center) mark; lower limit mark 250 cm³. No oil filter.

What engine oil does a Tohatsu MFS 2 / 2.5 / 3.5 use?

4-stroke engine oil, API SF, SG or SH; SAE 10W-30 or 10W-40; NMMA FC-W certified 10W-30.

What gear oil does a Tohatsu MFS 2 / 2.5 / 3.5 use, and how much?

Hypoid gear oil, API GL-5, SAE #90. Quantity: 180 cm³ (6 fl oz). Fill through the lower plug hole until oil flows from the upper hole without bubbles.

What spark plug does a Tohatsu MFS 2 / 2.5 / 3.5 use?

NGK DCPR6E. Gap: 0.8 to 0.9 mm (0.031 to 0.035 in); limit 1.0 mm (0.039 in).

How often should a Tohatsu MFS 2 / 2.5 / 3.5 be serviced?

The factory schedule lists: B models, initial 20 hours or 1 month; B models, every 50 hours or 3 months; B models, every 100 hours or 6 months; B models, every 200 hours or 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 Tohatsu MFS 2 / 2.5 / 3.5?

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 Tohatsu MFS 2 / 2.5 / 3.5?

Neutral 1,250 to 1,350 r/min after warm up; trolling in forward 1,150 to 1,250 r/min. Set the tachometer to 4 stroke 2 cylinder / 2 stroke 1 cylinder.

What is the propeller nut torque on a Tohatsu MFS 2 / 2.5 / 3.5?

Standard propeller [I7] 3 x 7-3/8 x 7 (3 x 188 x 178 mm) plastic.

Maintenance specs

Engine oil	4-stroke engine oil, API SF, SG or SH; SAE 10W-30 or 10W-40; NMMA FC-W certified 10W-30
Engine oil quantity	300 cm³ (10 fl oz) to the upper (center) mark; lower limit mark 250 cm³. No oil filter
Oil drain bolt (M8 x 1.25, 10 mm)	18 N·m (13 lb·ft) [1.8 kgf·m]; oil the washer, do not reuse the washer
Gear oil	Hypoid gear oil, API GL-5, SAE #90
Gear oil quantity	180 cm³ (6 fl oz). Fill through the lower plug hole until oil flows from the upper hole without bubbles
Gear oil plugs (2)	7 N·m (5 lb·ft) [0.7 kgf·m]; new gaskets
Gear case leak test	0.049 MPa (7 psi) [0.5 kgf/cm²], must hold for 10 seconds; do not go over this pressure
Spark plug	NGK DCPR6E
Spark plug gap	0.8 to 0.9 mm (0.031 to 0.035 in); limit 1.0 mm (0.039 in)
Spark plug torque (M12 x 1.25)	18 N·m (13 lb·ft) [1.8 kgf·m]; hand tight first
Idle speed	Neutral 1,250 to 1,350 r/min after warm up; trolling in forward 1,150 to 1,250 r/min. Set the tachometer to 4 stroke 2 cylinder / 2 stroke 1 cylinder
Thermostat	Starts to open 52 ± 2 °C (125 ± 4 °F); full open 65 ± 2 °C (150 ± 4 °F); lift 3.0 mm (0.12 in) or more (hold about 5 minutes before measuring)
Anode bolt	6 N·m (4 lb·ft) [0.6 kgf·m]; replace the anode when it is reduced to 2/3 of a new part; do not paint or oil it
Propeller	Standard propeller [I7] 3 x 7-3/8 x 7 (3 x 188 x 178 mm) plastic
Valve clearance, cold	IN 0.06 to 0.14 mm (0.0024 to 0.0055 in); EX 0.11 to 0.19 mm (0.0043 to 0.0075 in); piston at TDC compression ("T" mark, 5 mm hole in cam gear visible); pivot lock nut 10 N·m (7 lb·ft) [1.0 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. B models, 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. B models, every 50 hours or 3 months

   Replace: gear case oil, gear case plug gaskets, propeller cotter pin

   Check: fuel filter, water pump impeller, anodes

3. B models, 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, thermostat, anodes

4. B models, every 200 hours or 1 year

   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, thermostat, anodes

Source: Tohatsu 4 stroke 2/2.5/3.5 service manual; Tohatsu 4 stroke 2/2.5/3.5 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.