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Tohatsu MD75C2 / MD90C2 TLDI (3 cylinder, 1,267 cc, direct injection two-stroke) service guide

Oil, gear oil, spark plugs and the service schedule for the Tohatsu MD75C2 / MD90C2 TLDI (3 cylinder, 1,267 cc, direct injection two-stroke) (75 to 90 hp, two-stroke), from the factory service manual, plus how we service it in Hawaiʻi.

Models covered: TLDI75C2 EPTO and TLDI90C2 EPTO: 2 stroke direct fuel injection (TLDI), 3 cylinders, 1,267 cm3 (77 cu in), bore 86 x stroke 72.7 mm; 55.2 kW (75 ps) and 66.2 kW (90 ps); WOT 5,150 to 5,850 r/min; remote control, electric start, auto-lube oil injection under ECU control with a 4.3 L oil tank; gear ratio 1:2.33 (12:28) on both. The earlier MD70B / MD90B have their own sheet.

Quick answers

What two-stroke oil does a Tohatsu MD75C2 / MD90C2 TLDI use?
Genuine oil: oil for two stroke direct injection engines recommended by the outboard manufacturer.
What gear oil does a Tohatsu MD75C2 / MD90C2 TLDI use, and how much?
Hypoid gear oil, API GL-5, SAE #80 to #90. Quantity: 900 cm3 (30.4 fl oz).
What spark plug does a Tohatsu MD75C2 / MD90C2 TLDI use?
NGK IZFR6Q, qty 3. Gap: 0.7 to 0.8 mm (0.029 to 0.032 in), functional limit 0.9 mm (0.036 in).
How often should a Tohatsu MD75C2 / MD90C2 TLDI be serviced?
The factory schedule lists: Initial 20 hours or initial 1 month; At 50 hours or every 3 months; At 100 hours or every 6 months; At 200 hours or every year; Every 2 years, done with every second yearly service. 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 MD75C2 / MD90C2 TLDI?
The factory schedule says to replace it at 200 hours and 400 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 MD75C2 / MD90C2 TLDI?
700 / 800 / 900 r/min, in neutral and in forward.
What is the propeller nut torque on a Tohatsu MD75C2 / MD90C2 TLDI?
12 N·m (9 lb-ft, 1.2 kgf·m), then tighten further until the split pin hole lines up; new split pin.

Maintenance specs

Injection (two-stroke) oilGenuine oil: oil for two stroke direct injection engines recommended by the outboard manufacturer
Oil tank4.3 L (1.14 US gal); electric oil pump under ECU control
Gear oilHypoid gear oil, API GL-5, SAE #80 to #90
Gear oil quantity900 cm3 (30.4 fl oz)
Gear oil drain and level plugs (lower and upper oil plug)Remove the lower oil plug first, then the upper; fill through the lower hole until oil comes from the upper hole; fit the upper plug first. New gasket on both plugs (do not reuse)
Gear case pressure test0.05 MPa (7 psi, 0.5 kgf/cm2) at the upper oil plug hole
Spark plugNGK IZFR6Q, qty 3
Spark plug gap0.7 to 0.8 mm (0.029 to 0.032 in), functional limit 0.9 mm (0.036 in)
Spark plug torque25 N·m (18 lb-ft, 2.5 kgf·m)
Idle / trolling speed700 / 800 / 900 r/min, in neutral and in forward
ThermostatWith wax type pressure relief valve: valve opening temperature 60 °C (140 °F); full-open 75 °C (167 °F) or higher; valve lift 4.5 mm (0.177 in) or more at 75 °C
Fuel filtersLow pressure fuel filter with cup (red float shows water): clean the cup, replace the filter if necessary. High pressure fuel filter: cartridge type, disposable, replace periodically. Air compressor air filter: replace when the paper turns brownish (clogged)
Propeller nut12 N·m (9 lb-ft, 1.2 kgf·m), then tighten further until the split pin hole lines up; new split pin.
Power trim and tilt fluidATF Dexron III, 682 cm3 (23.1 fl oz)
Air compressor drive beltTension 100 to 150 N (Unitta tension gauge); deflection 4 to 6 mm (0.16 to 0.24 in) when pushed with 20 N, adjusted cold by moving the compressor. Replace if worn, damaged, cracked, chipped or oily. Driven pulley nut 50 N·m; drive pulley (flywheel nut) 260 N·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 initial 1 month

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

    Check: spark plugs, fuel filter

  2. At 50 hours or every 3 months

    Replace: gear case plug gaskets, propeller cotter pin

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

  3. At 100 hours or every 6 months

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

    Check: spark plugs, fuel filter, water pump impeller, thermostat, anodes

  4. At 200 hours or every year

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

    Check: spark plugs, fuel filter, thermostat, anodes

  5. Every 2 years, done with every second yearly service

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

    Check: spark plugs, thermostat, anodes

Source: Tohatsu TLDI 75/90C2 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.

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