D348 MARINE ENGINE Operating Under Abnormal Conditions Caterpillar

Operating Under Abnormal Conditions
1.1. Duplex Oil Filter and Duplex Fuel Filter Systems
2.1. Engine Jacket Water Pump Failure
3.1. Engine Sea Water Pump Failure
4.1. Engine Lubricating Oil Pump Failure
5.1. Marine Gear Oil Pump Failure
6.1. Towing
7.1. Come-Home Feature

Certain worldwide marine classification societies require seagoing propulsion engines to be equipped so as to allow continuous operation while oil and fuel filters are changed; or if the engine water pump or oil pump should fail; or if the marine gear oil pump should fail.

Duplex Oil Filter and Duplex Fuel Filter Systems

These two filter systems are available as attachments on 5.4" (137 mm) and 6.25" (159 mm) bore V-engines. These systems permit changing plugged filter elements without stopping the engine. Plugging of the elements can be determined by observing the oil filter change indicator or the fuel pressure gauge reading.



The oil filter change indicator is located on the oil filter housing. When the indicator is raised approximately one half to two thirds the height of the viewing glass, the filter element requires changing.

The fuel pressure gauge is mounted in the instrument panel. When the fuel pressure gauge registers in the OUT range (less than 20 PSI, or less than 1.4 kg/cm2) the fuel filters must be changed.

For V-engines only, see the LUBRIAVSION AND MAINTENANCE PROCEDURES for detailed instructions for changing the filter elements.

Engine Jacket Water Pump Failure

If the engine jacket water pump should fail, fresh water can be supplied to the engine jacket using the emergency water system.

6.25" (159 mm) Bore V-Engines Emergency Jacket Water Connections

1 Tee Connector

2 Valve

3 Emergency Jacket Water Pump

4 Tee Connector

5 Valve or Plate

1. Stop the engine. If the water pump bearing has failed, the water pump need not be removed.
2. Open valve (2).
3. Loosen, move and secure valve, or plate, (5) in the EMERGENCY position.
4. Start the emergency jacket water pump (3). Allow the air to escape from the emergency cooling system. Check the coolant level. Add fresh water as required.
5. Start the engine.
6. Engage the marine gear; operate the vessel at normal speed.

If the fresh coolant water is lost (such as when a water line fails) and an insufficient supply is available to replenish the jacket water coolant while at sea, sea water may be pumped through the engine jacket if it is necessary.

1. Stop the engine and make the necessary water pump and lines connections for pumping sea water into the jacket water system and back to the sea.
2. Remove the temperature regulating thermostats from the regulator housing, and install the housing cover.
3. Start the emergency pump and/or start the engine.

NOTE: The sea water should be pumped through the engine jacket and returned to the sea.

4. With the governor control at low idle, engage the marine gear forward clutch.
5. Operate the engine at the lowest speed for existing sea conditions.
6. Maintain engine temperatures as slow as possible in order to minimize salt corrosion of engine parts and salt deposits in the engine.
7. Upon reaching port, have the engine jacket water system completely disassembled, cleaned and inspected. Replace all parts which are corroded or damaged.

Engine Sea Water Pump Failure

The sea water pump circulates sea water through the engine jacket water heat exchanger. On turbocharged-aftercooled engines, the sea water also cools the aftercooled air. If the sea water pump should fail:

1 Valve - normally closed

2 Emergency sea water pump

3 Emergency sea water inlet

4 Valve - normally closed

5 Emergency sea water strainers

6 Normal - operation sea water strainers

7 Normal - operation sea water inlet

8 Valve - normally open

9 Sea water pump

10 Jacket water heat exchanger

11 Sea water outlet

12 Aftercooler

1. Stop the engine. If the shaft bearing has failed, the damaged pump need not be removed.
2. Close the inlet valve (8) to the sea water pump.
3. Open the inlet valve (4) to the emergency sea water pump.
4. Start the emergency sea water pump (2).
5. Start the engine, engage the marine gear, and continue at normal speed.

Engine Lubricating Oil Pump Failure

If the engine oil pump fails, oil pressure will drop and the engine water temperature gauge readings may be above normal. If equipped, the shutoff controls will stop the engine.

To use the emergency lubricating pump:

1. Move the marine gear selector lever to the NEUTRAL position, and stop the engine.
2. Check the engine oil level. Maintain the level at the FULL mark on the dipstick.
3. Reset the oil pressure shutoff control. Start the standby lubricating pump (3).


1. Oil Pan

2. Oil Strainer

3. Standby Lubricating Oil Pump

4. Check Valve

5. Oil Cooler

6. Engine Oil Filter

7. Engine Lube Pump

4. Observe the oil pressure gauge; be sure the oil pressure shutoff control reset knob has turned to the RUN position. Start the engine.
5. Engage the marine gear; operate the vessel at normal speed.

Marine Gear Oil Pump Failure

Marine gears have a lubrication system which is independent from the engine lubrication system. The AVSpare 7200 Series Marine Gears may be equipped with an emergency lubricating oil system, as shown in the illustration, which can provide proper lubrication to the marine gear should the marine gear oil pump fail.

1. Emergency Lube Oil Valve

2. Marine Gear Case

3. Tapped Holes In Marine Gear Case

4. Strainer

5. Emergency Lube Oil Pump

6. Output Flange

When the marine gear oil pump fails, engagement of the clutches will become sluggish and the clutch plates will slip or disengage. The shaft bearings will not receive pressure lubrication.

To use the emergency marine gear oil pump:

1. Stop the engine.
2. Loosen, move and bolt the handle of the emergency valve into the EMERGENCY position.

3. Start the emergency lube oil pump (5).
4. Observe the reading of the marine gear oil pressure gauge.
5. Check the marine gear oil level with the emergency pump running.
6. Maintain the oil level at the FULL mark on the dipstick.
7. If the engine is not to be started (if the vessel is going to be towed by another vessel) the propeller can now windmill in the water without causing damage to the marine gear shaft bearings.
8. If the vessel is to continue under its own power; start and warm the engine, engage the marine gear, and continue traveling at normal speed.


If the vessel cannot continue under its own power, it is recommended that the vessel be towed. If pressurized oil cannot be supplied to the marine gear shaft bearings while being towed, the propeller shaft must be secured so as to prevent the turning shaft (caused by the propeller windmilling through the water) from damaging the marine gear shaft bearings.


Turning of the propeller shaft without proper lubrication will damage the marine gear shaft bearings.

After the shaft has been secured, have the towing vessel travel at slow speed in order to minimize the windmilling force on the propeller.

There are several ways of preventing shaft rotation; the correct method depends upon the turning force of the propeller, and the construction of the propeller shaft tunnel. Use the method best suited for the type of installation:

Wrapping Propeller Shaft:

1. On small vessels, wrap a heavy rope around the propeller shaft. The number of wraps needed will depend upon the mass of the propeller and propeller shaft.
2. Secure the rope in the opposite direction of shaft rotation.

Securing Companion Flange:

1. Remove one or more bolts from the companion flange coupling.
2. Bolt a chain to the companion flange.
3. Wrap the chain several times around the propeller shaft.
4. Secure the loose end of the chain at a right angle to the shaft and in opposite direction of shaft rotation.

Applying Air Actuated Shaft Brake:

For vessels equipped with a shaft brake, the shaft brake may be applied if there is air pressure available.

Come-Home Feature

If the marine gear loses oil pressure, and if there is no other means for returning to port, the come-home feature can be used. This feature allows the forward clutch to be mechanically engaged by tightening bolts or setscrews which compress the clutch pack. Once the clutch is mechanically locked, the clutch cannot be disengaged with the engine running. The rear clutch cannot be mechanically engaged: The vessel can only travel forward.


Use the come-home feature only in an emergency. If the marine gear lubricating oil pressure is lost, travel with extreme care and at minimum engine speed to avoid damaging the bearings.

1. The engine must be warm. If necessary, start and idle the engine until it is warm.
2. Stop the engine.
3. Mechanically engage the "forward" clutch as described below. The "forward" clutch is the rear most clutch inside the clutch housing.

AVSpare 7200 Series:

3a. Remove the access cover from the gear housing.

3b. Install 5/8-11, 2 inch (50.8 mm) bolts in the tapped holes of the rear most clutch. Alternately tighten the bolts until the clutch is uniformly engaged.

3c. Install the access cover. Continue with steps 4 - 8.

Twin Disc MG500 Series:

3a. Remove the square-headed pipe plugs from the rear housing.

3b. Alternately tighten the setscrews until the forward clutch is engaged.

All Marine Gears:

4. Check the marine gear oil level. Maintain oil at the FULL mark on the dipstick.
5. Start the engine.


The starter motor will be turning the diesel engine, marine gear, propeller shaft, and propeller while cranking. Avoid creating excessive heat in the starter by overcranking: Damage can result.

6. After starting, travel with caution; usually at minimum speed.
7. To stop the vessel, stop the engine. Remove the bolts engaging the clutch when the engine is topped.
8. Upon reaching port, disassemble and inspect the clutch plates for warpage and cracking: Damage can occur by having been mechanically engaged. Under severe operating conditions, the marine gear should be disassembled and all bearings inspected closely.