Yanmar 4TNE88A Engine

1. Warm up the engine, then gradually increase speed up to the no-load max. revolution.
2. Adjust with the no-load max. revolution adjusting bolt if it differs.
3. Set the engine to idling revolution by turning the no-load min. revolution adjusting bolt.

⚠ If the valve cap is worn or damaged on the head, replace it with a new one.

⚠ Make sure the valve cap is nested on the head of intake/exhaust valves.

Tools: Thickness gauge

1. Inspect and adjust the valve head clearance while the engine is cold.
2. Raise the piston of the cylinder to top dead center (TDC) of compression.
3. Loosen the lock nut and adjusting screw; ensure the valve cap is free from inclination or dirt.
4. Insert a thickness gauge between rocker arm and valve cap.
5. Tighten the adjusting screw until clearance is attained.

⚠ Increase shim thickness to delay timing; decrease to advance timing.

1. Turn the engine in the specified direction using the crankshaft pulley.
2. Check injection timing at the delivery valve of cylinder No.1 when oil level rises.
3. Identify the timing mark on the flywheel through the access hole of the flywheel housing.
4. If timing differs from specified, remove the fuel injection pump and adjust by increasing or decreasing the adjusting shim thickness.

⚠ Do not apply over 5 kg/cm2 to the actuator.

⚠ If adjustment is impossible, replace the whole turbocharger ass'y.

Tools: Dial gage, Manometer, Pressure regulating valve, Pressure reducing valve, Pressure gage

1. Set the manometer control pressure (Pc) applied to the waste gate actuator to 0 and set the dial gage to zero.
2. Gradually open the pressure regulating valve and measure the Pc value when the actuator rod is operated by 2 mm.
3. For hysteresis, let the rod move to 3 mm then gradually close the valve and measure pressure at 2 mm.
4. Apply 1.2 kg/cm2 to the actuator and hold for 1 minute; the actuator is good if pressure is 1.1 kg/cm2 or more.

Tools: Tester

1. Remove the connector from the L.O. pressure switch.
2. While running the engine, bring the tester probes into contact with the switch terminal and cylinder block.
3. If the tester shows continuity, the L.O. pressure switch is defective.

Tools: Nozzle tester, White paper

1. Pump the lever of the nozzle tester 4-6 times per second at the specified injection pressure.
2. Make sure the pattern is neither stream nor sliver.
3. Place white paper 30 cm below the nozzle; spray should form a perfect circle.
4. Ensure no oil drips after injection and no ooze below specified pressure.
5. Retighten and test again if excessive oil leaks from the overflow coupling.

Tools: Thermometer, Tester

1. Put the thermostat into water in a container and heat while measuring water temperature.
2. Make sure the thermostat functions at 69.5-72.5 C.
3. Put the thermoswitch into antifreeze or oil and heat while measuring liquid temperature.
4. If the tester shows continuity at 107-113 C, the thermoswitch is acceptable.

⚠ Never fail to attach the gasket to the tip of the adapter.

Tools: Compression gauge, Compression gauge adapter

1. Warm up the engine.
2. Remove the fuel injection pipe and fuel injection valve from the cylinder to be measured.
3. Crank the engine with regulator handle at STOP before attaching the gauge adapter.
4. Attach the compression gauge adapter and compression gauge to the cylinder.
5. Crank the engine with the starting motor until the reading stabilizes.

⚠ Thoroughly remove carbon deposits from the injection nozzle before measurement.

Tools: Nozzle tester

1. Thoroughly remove carbon deposits from the injection nozzle.
2. Connect the fuel injection valve to the high pressure pipe of the nozzle tester.
3. Pump the lever slowly and read the pressure gauge when injection starts.
4. If measured pressure is lower than specified, replace the pressure adjusting shim with a thicker one.

⚠ For a new nozzle, remove the seal peel and remove rust-preventive oil before use.

Tools: Clean diesel oil

1. Thoroughly wash the nozzle valve using clean diesel oil.
2. Hold the nozzle body vertically and lift the nozzle valve approx. 1/3 of its length.
3. Check that the nozzle falls smoothly by its own gravity when released.

1. Push the center of the V-belt between the alternator and cooling water pump with a finger.
2. If deflection is 10-15 mm, the V-belt tension is acceptable.
3. If not, adjust the tension using the adjuster at the alternator.

Tools: Battery tester, Hydrometer

1. Check the electrolyte level in each cell; add deionized water to UPPER LEVEL if low.
2. Using a battery tester or hydrometer, check the state of the battery; recharge if discharged.
3. Repair or clean the terminals if corroded or soiled.
4. Repair or replace the fittings if corroded; re-tighten if loosened.
5. Replace the battery if cracked or deformed; clean with fresh water if contaminated.