0391798 JOHNSON PISTON ASSY.,Std.

Walk-Around Inspection
For any type of leak, clean up the fluid. If leaking is observed, find the source and correct the leak. If leaking is suspected, check the fluid levels more often than recommended until the leak is found or fixed, or until the suspicion of a leak is proved to be unwarranted.
To obtain maximum service life for your engine, make a thorough inspection before starting the engine. Make a walk-around inspection of the installation. Look for items such as oil or coolant leaks, loose bolts and trash buildup. Remove any trash. Make repairs, if necessary.
The guards must be in the proper place. Repair damaged guards or replace missing guards.
Ensure that the areas around the rotating parts are clear.Air Inlet System
Unburned gas in the air inlet and exhaust system may ignite when the engine is started. Personal injury and/or property damage may result.Before starting an engine that may contain unburned gas, purge the unburned gas from the air inlet and exhaust system. Refer to the topic on purging unburned gas in the "Starting the Engine" section.
Ensure that the air inlet piping and the air filters are in place.
Ensure that all clamps and connections are secure.
Inspect the air cleaner service indicator (if equipped). Service the air cleaner filter element when the yellow diaphragm enters the red zone, or the red piston locks in the visible position.Cooling System
Inspect the cooling system for leaks or loose connections. Inspect the condition of all the hoses and pipes for the cooling system. Ensure that the connections are properly clamped.
Inspect the water pumps for evidence of leaks.
Check the coolant level. Add coolant, if necessary. For information on the proper coolant to use, see this Operation and Maintenance Manual, "Refill Capacities and Recommendations" (Maintenance Section).Driven Equipment
If necessary, check the oil levels of the driven equipment. Perform any maintenance that is required for the driven equipment. Refer to the literature that is provided by the OEM of the driven equipment.
If the engine is equipped with a clutch, ensure that the clutch is disengaged.
For generator set engines, ensure that the main circuit breaker is open.Electrical System
Inspect the wiring for the following conditions:
Loose connections
Wiring that is worn or frayedInspect the gauge panel and the control panel for good condition. Reset any shutoff or alarm components.Fuel System
NEVER use a flame to check for gas leaks. Use a gas detector.An open flame can ignite mixtures of air and fuel. This will cause explosion and/or fire which could result in severe personal injury or death.
Check the fuel lines for leaks with a gas detector.
Inspect the fuel lines for loose fittings and leaks. Ensure that the fuel lines are properly clamped.
Ensure that the fuel is supplied to the engine at the correct pressure for the engine.Lubrication System
Illustration 1 g00760044
Oil level gauge (dipstick)
(1) "ADD" mark
(2) "FULL" mark
Excessive engine oil will increase oil consumption and result in excessive deposits in the combustion chamber. Do not overfill the engine with oil.
Check the engine crankcase oil level. Maintain the oil level between the "ADD" and "FULL" marks on the "ENGINE STOPPED WITH OIL COLD" side of the oil level gauge. For information on the proper oil to use, see this Operation and Maintenance Manual, "Refill Capacities and Recommendations" (Maintenance Section).
Check for leaks at the following components: crankshaft seals, crankcase, oil filters, oil gallery plugs, sensors and valve covers.
Inspect the tubes, tee pieces, and clamps on the crankcase breathers.Starting System
Note: If the engine is equipped with a system for external support, prepare the system before starting the engine. Ensure that all of the systems for engine support are enabled. Perform all prestart checks for the control system.Air Starting Motor
Drain moisture and sediment from the air tank and from any other air piping.
Check the oil level in the lubricator. Keep the lubricator at least half full. Add oil, if necessary. For temperatures above 0 °C (32 °F), use a nondetergent 10W oil. For temperatures below 0 °C (32 °F), use air tool oil.
Check the air pressure for starting. The air starting motor requires a minimum of 690 kPa (100 psi). The maximum allowable air pressure is 1030 kPa (150 psi). Open the air supply valve.Electric Starting Motor
Disconnect any battery chargers that are not protected against the high current drain that is created when the electric starting motor engages.Inspect the wiring, the electrical cables, and the battery for the following conditions:
Loose connections
Wires that are worn or frayed
Corrosion