D346 MARINE ENGINE Starting The Engine Caterpillar

Starting The Engine
1.1. Electric Starting
2.1. Air Starting:
3.1. After Engine Starts


Do not engage the starter when the flywheel is moving.

Electric Starting

1. Use starting aids if required. See the topic, GENERAL, Cold Weather Starting.

NOTE: D349 and D399 Engines:

When the START switch is turned to the START position, a prelube pump driven by an electric motor will pressurize the engine lubrication system with oil. The crankcase oil will develop sufficient pressure before closing a switch which will energize the starting motor(s). The motor(s) will then crank the engine. After the engine starts, the starter switch is released, the prelube pump stops and the engine oil pump continues lubricating the lube system.


Prelube time will vary with the temperature of the oil. Hot oil will require more time to attain oil pressure than will cold oil.

2. Push the START button; or, turn the HEAT-START switch to the START position; or, turn the ON-OFF-STOP switch to the ON position, depending upon how the engine is equipped. Release the control as soon as the engine starts.


If the engine is equipped with either a Woodward PSG or UG8 Governor, see the topic WOODWARD GOVERNORS for the governor operation instructions.



If the engine fails to start after 30 seconds of cranking, allow the starter to cool for 2 minutes before repeating the starting procedure.


NEVER use starting aids when the engine is warm and running.

Air Starting:

1. Open and close the bleed valve on the bottom of the air tank to drain condensation and oil carryover.
2. Check the air supply pressure. The air start must have 100 PSI (7 kg/cm2) to operate properly.
3. Check the oil level in the oiler jar. Keep jar at least half full. Add oil if necessary. See the LUBRIAVSION AND MAINTENANCE PROCEDURES, Filling Motor Oiler.

4. Check the oil level in the collector jar. When the jar is half full, empty the jar. Do not reuse this oil.

5. Pull the air valve upward to crank the engine. As soon as the engine starts, release the valve.

The engine governor may be controlled by an air regulator valve. One control panel can regulate several synchronous operating engines.

AIR REGULATOR VALVE - Small Bore Engines


After Engine Starts

1. Observe the oil pressure gauge immediately after starting.


If no oil pressure is indicated, stop the engine and have necessary repairs made.

2. As soon as oil pressure is registered, increase engine speed and see if ample water is flowing from the sea water discharge.

If water is not visible, stop the engine and check the priming procedure. If it is difficult to get the pump to pump water satisfactorily, contact your AVSpare dealer.

If the water flow appears restricted:

a. Stop the engine.
b. Check and clean the inlet screen and the sea water strainer of debris.
c. Vent and fill the sea water suction line if necessary.
d. Start the engine.
e. Check for proper water flow.

------ WARNING! ------

Stop the engine if any repairs or adjustments are required. Do not service the equipment while the engine is running.

3. Move the governor control to low idle, allow the engine to warm (usually several minutes). Make another "walk-around" inspection for leaks, etc.