Tohatsu MFS140A / MFS140ACR (2.0 L four-stroke) service guide

Quick answers

How much oil does a Tohatsu MFS140A / MFS140ACR take?

4,200 mL (4.44 US qt) with filter; 4,000 mL (4.23 US qt) without filter.

What engine oil does a Tohatsu MFS140A / MFS140ACR use?

Tohatsu 4-Stroke Engine Oil, API SH, SJ or SL, SAE 10W-30 or 10W-40.

What gear oil does a Tohatsu MFS140A / MFS140ACR use, and how much?

Tohatsu Gear Oil, API GL-5, SAE #80-90. Quantity: 1,000 mL (33.8 fl oz); same for standard and counter rotation.

What spark plug does a Tohatsu MFS140A / MFS140ACR use?

NGK LKR6E. Gap: 0.8 to 0.9 mm (0.032 to 0.035 in).

How often should a Tohatsu MFS140A / MFS140ACR be serviced?

The factory schedule lists: Initial 20 hours or 1 month; Every 100 hours or 6 months; Every 200 hours or 1 year; Every 400 hours or 2 years. 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 MFS140A / MFS140ACR?

The factory schedule says to replace it at 400 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 MFS140A / MFS140ACR?

700 r/min.

What is the propeller nut torque on a Tohatsu MFS140A / MFS140ACR?

35 N·m (26 lb·ft) [3.5 kgf·m].

Maintenance specs

Engine oil	Tohatsu 4-Stroke Engine Oil, API SH, SJ or SL, SAE 10W-30 or 10W-40
Engine oil quantity	4,200 mL (4.44 US qt) with filter; 4,000 mL (4.23 US qt) without filter
Oil filter	18 N·m (13 lb·ft) [1.8 kgf·m]; Oil filter bolt 40 N·m (29 lb·ft)
Oil pan drain bolt (M14 x 1.5)	24 N·m (18 lb·ft) [2.4 kgf·m]; new gasket
Gear oil	Tohatsu Gear Oil, API GL-5, SAE #80-90
Gear oil quantity	1,000 mL (33.8 fl oz); same for standard and counter rotation
Gear oil plugs (M8 x 1.25)	4 N·m (3 lb·ft) [0.4 kgf·m]; new gaskets
Gear case leak test	0.05 MPa (7 psi) [0.5 kgf/cm²] held 10 seconds
Spark plug	NGK LKR6E
Spark plug gap	0.8 to 0.9 mm (0.032 to 0.035 in)
Spark plug torque	18 N·m (13 lb·ft) [1.8 kgf·m]
Idle speed	700 r/min
Thermostat	Starts to open 60 ± 1.5 °C (140 °F); fully open 75 °C (167 °F); lift 4.5 mm (0.18 in) or more
Cooling water pressure (reference)	Neutral: 700 r/min 5 kPa (1 psi); 850 r/min 15 kPa (2 psi); 2000 r/min 35 kPa (5 psi). Forward 3000 to 6000 r/min 40 kPa (6 psi)
Anodes	Cooling passage anode screw 2.5 N·m (1.84 lb·ft); anode plug 18 N·m (13 lb·ft). Replace at 2/3 of new size
Propeller nut (M16 x 1.5)	35 N·m (26 lb·ft) [3.5 kgf·m]
Power trim and tilt fluid	ATF DEXRON III; 682 mL (23.1 fl oz); reservoir cap 0.7 N·m (0.5 lb·ft)
Valve clearance, cold	IN 0.20 to 0.24 mm (0.008 to 0.0095 in); EX 0.30 to 0.34 mm (0.012 to 0.0135 in); lock nut 7 N·m (5 lb·ft)
Timing belt	Check for cracks, damage, wear; replace if necessary (no deflection spec). Tensioner bolt 40 N·m (30 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

   Check: fuel filter

2. 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, anodes

3. Every 200 hours or 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

4. Every 400 hours or 2 years

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

   Check: spark plugs, 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: Tohatsu 4 Stroke MFS75A/90A/100A/115A/140A/150A service manual, OB No. 003-21075-3BE1. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.