SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Caterpillar


Systems Operation

Usage:

Introduction

When the words "use again" are in the description, the specification given can be used to determine if a part can be used again. If the part is equal to or within the specification given, use the part again.

When the word "permissible" is in the description, the specification given is the "maximum or minimum" tolerance permitted before adjustment, repair and/or new parts are needed.

A comparison can be made between the measurements of a worn part and the specifications of a new part to find the amount of wear. A part that is worn can be safe to use if an estimate of the remainder of its service life is good. If a short service life is expected, replace the part.

Electrical System

Wiring Diagrams


Pilot Panel Wiring Schematic (3116 & 3126 Engines)

Engine and Junction Box (3116 Engine)

Wiring Diagram Notes

Only one fuel shutoff solenoid will be installed on the engine. Only the wires for the installed solenoid will be provided.

Component shown dashed is located in the junction box.


Junction Box Diagram (3116 Engine 7E1330 Wiring Diagram)


Engine Diagram (3116 Engine 7E1330 Wiring Diagram)


Engine Diagram (3116 Engine 113-1100 Wiring Diagram)


Junction Box Diagram (3116 Engine 113-1100 Wiring Diagram)

Engine and Junction Box (3126 Engine)

Wiring Diagram Notes

Only one fuel shutoff solenoid will be installed on the engine. Only the wires for the installed solenoid will be provided.

Component shown dashed is located in the junction box.


Junction Box Diagram (3126 Engine)


Engine Diagram (3126 Engine)

Components

Water Temperature Contactor

A water temperature contactor switch is located in the cooling system. This unit is non-adjustable. Thermal expansion of the element operates a micro-switch that signals an alarm on the pilot panel. The water temperature element must be in contact with the coolant. After an overheated engine is allowed to cool, the contactor automatically resets itself.

Oil Pressure Switch

An oil pressure switch is located in the oil system. This switch has three terminals and serves a dual purpose. One use of this switch is to power the hour meter after the engine oil pressure reaches normal operating pressure. The other use is to signal an alarm on the pilot panel when engine oil pressure drops below the desired oil pressure.

Control Relay

This is a standard type relay that, when energized, has contacts that open across one circuit and close across another circuit. The circuits are wired so that when the relay is energized voltage from the battery will go to and energize the fuel shutoff solenoid (on engines equipped with an energize to run type of solenoid). On engines which use a latching type (energize to shutoff) fuel solenoid, the control relay is de energized and voltage flows from the battery to the STOP terminal on the fuel shutoff solenoid. This in turn shuts down the engine.

Electrical Indicators And Sending Units

The electrical indicators and sending units operate in electrical balance. Because of this, the voltage and resistance ratings are important to get the correct indications on the indicators.

Water Temperature Sending Unit


Sending Unit for Water Temperature
(1) Bulb. (2) Nut. (3) Connection.

The sending unit for water temperature is an electrical resistance. It changes the value of its resistance according to the temperature which the bulb (1) feels.

The sending unit is in a series circuit with the electrical indicator. When the temperature is high, the resistance is low. This makes the indicator have a high reading.

The sending unit must be in contact with the coolant. If the coolant level is too low because of a sudden loss of coolant while the engine is running or because the level is too low before starting the engine, the sending unit will not work correctly.

Pressure Sending Unit


Sending Unit for Pressure
(1) Connection. (2) Fitting.

The sending unit for pressure is an electrical resistance. It has a material which changes electrical resistance according to pressure which it feels.

The sending unit for pressure is in a series circuit with the electrical indicator. As the pressure on the sending unit changes, the reading on the indicator changes in the same way.

Fuel System

Fuel Cooler (If Equipped)


Location Of Fuel Cooler (Left Side View)
(1) Fuel return fitting. (2) Return to cooler line. (3) Fuel cooler.

The fuel cooler (3) may be used in a marine application. The fuel cooler helps reduce the heat felt in a cabin because the fuel tank may be located close to an interior wall or in the floor. Additionally, the fuel cooler (3) is used to help control fuel temperatures, which when elevated can result in reduced overall engine performance. Fuel coolers (3) are recommended for applications where fuel tanks are small and/or where engines are operated for long periods of time with lower fuel levels.

When an engine is equipped with a fuel cooler (3) then the excess fuel that is not burned in the combustion process is routed from the engine through the fuel return to cooler line (2) to the fuel cooler (3). The hot fuel passes through the core portion of the fuel cooler (3) which is surrounded by the water being pulled into the sea water/separate circuit water pump. Once the fuel passes through the core it is returned to the fuel tank through a line attached to fuel return fitting (1).

NOTE: The fuel cooler group can not be used on the 3116, 3126 Keel Cooled Engines.

Air Inlet Heater (3126)

To aid starting and prevent white smoke emission at start up, the Caterpillar 3126 Marine Engines are equipped with an electric heater located at the air inlet casting. Under the proper conditions of jacket water temperature, oil pressure, ignition position, and elapsed time, an electronic control module switches the heater system on. The system is capable of delivering heat for thirty seconds prior to start up, during cranking, and up to five minutes continuous and fifteen minutes of cycling (ten seconds on, ten seconds off) after the engine has started.

If for any reason the air inlet heater system malfunctions, the engine will start and run. The only concerns may be the amount of "white smoke" present and the possible need to use an alternative starting aid.

System Components

The basic components of the air inlet heater system are: Magnetic switch, heater element, coolant temperature switch, electronic control module, oil pressure switch, and an indicator lamp.


Location Of Components
(1) Control module. (2) Magnetic switch.


Location Of Components
(3) Inlet manifold. (4) Air inlet heater. (5) Oil pressure switch. (6) Aftercooler. (7) Coolant temperature switch. (8) Water temperature regulator housing.

The magnetic switch is normally located in the junction box. It turns the 12V (or 24V) heater ON and OFF in response to signals from heater control module (1).

The air inlet heater (4) is located between the inlet manifold (3) and aftercooler (6). The center terminal is positive, the front and rear terminals are negative. The negative terminals are grounded to the starting motor. A gasket is used on each side of the heater element.

The coolant temperature switch (7) is located in the water temperature regulator housing (8) or the water collector elbow in the keel cooled engines. In order to activate the system, the coolant temperature must have dropped below the lower limit of the switch. Above the upper limit, the switch is open, and the air inlet heater system will not function. Between the lower and upper temperature limits, the switch may be open or closed.

The heater control module (1) is mounted inside the junction box. The heater control module requires input from the oil pressure switch (5) and coolant temperature switch (7) to control the heating cycle of the heater element.

The oil pressure switch (5) is located in the oil manifold. The switch is normally open below 240 ± 70 kPa (35 ± 10 psi). Above the limit, the switch closes, indicating to the control module that the engine is running. The indicator lamp can be located in the instrument panel. It has an amber lens and informs the operator when the system is active.

Lamp Test

When the ignition switch is turned to the "RUN" position, the control module energizes the magnetic switch, supplying the heater element with power for two seconds. The indicator lamp in the instrument panel should illuminate at that time. Failure of the lamp to illuminate indicates a system or lamp malfunction.

NOTE: If the coolant temperature is below the lower limit of the temperature switch, the system should go directly from the lamp test into the pre-heat cycle (light will not turn off).

Pre-Heat Cycle

Three conditions must exist before the air inlet heater will operate in the pre-heat cycle:

1. The ignition switch must be in the "RUN" position or the key switch in the "ON" position.
2. The coolant temperature is below the lower limit of the temperature switch.
3. The air inlet heater has not timed out for thirty seconds in the pre-heat cycle.

There are three ways to end the pre-heat cycle:

1. The ignition switch is turned to the "START" position or the start button is pressed.
2. The ignition switch is turned to the "OFF" position.
3. The system reaches the thirty second time limit.

Crank Heat Cycle

Three conditions must exist before the air inlet heater will operate in the crank heat cycle:

1. The ignition switch is in the "START" or "ON" position, or the start button is pressed.
2. The coolant temperature is below the lower limit of the temperature switch.
3. The air inlet heater has not timed out for thirty seconds in the pre-heat cycle. The thirty second timer starts when the ignition switch is turned to the "START" or "ON" position, or the start button is pressed and continues with the engine not running. It is continually reset as long as the ignition remains in the "START" or "ON" position.

There are three ways to end the crank heat cycle:

1. The ignition switch is turned to the "OFF" position.
2. The engine starts.
3. The system reaches the thirty second time limit with the ignition in the "RUN" position and the engine not operating. Crank heat will resume when the engine is returned to the "START" position.

Regular Heat Cycle

Four conditions must exist before the air inlet heater will operate in the regular heat cycle:

1. The ignition switch must be in the "RUN" or "ON" position.
2. The coolant temperature is below the upper limit of the temperature switch.
3. The engine oil pressure is above 240 ± 70 kPa (35 ± 10 psi).
4. The air inlet heater has not timed out for five minutes in the regular heat cycle plus fifteen minutes of cycling ten seconds "ON" and ten seconds "OFF".

There are four ways to end the regular heat cycle:

1. The ignition switch is turned to the "OFF" position. When the switch is turned to the "OFF" position, the regular heat cycle is terminated.
2. The engine stalls.
3. The coolant temperature exceeds the upper limit of the temperature switch.
4. The system reaches its twenty minute time limit.


Air Inlet Heater Electrical Schematic (Typical Example)


Air Inlet Heater Controller Functional Flow Chart

Cooling System

3116 Heat Exchanger (Jacket Water Cooling Circuit)


Cooling System Schematic
(1) Shunt line. (2) Pressure cap. (3) Expansion tank. (4) Vent line (air). (5) Heat exchanger (tube bundle). (6) Aftercooler. (7) Cylinder block and cylinder head. (8) Inside bypass line. (9) Watercooled turbocharger. (10) Water pump. (11) Engine oil cooler. (12) Watercooled exhaust manifold. (13) Water temperature regulator housing. (14) Hot water to heat exchanger.

3126 Heat Exchanger (Jacket Water Cooling Circuit)


Cooling System Schematic
(1) Shunt line. (2) Pressure cap. (3) Expansion tank. (4) Vent line (air). (5) Heat exchanger (tube bundle). (6) Cylinder block and cylinder head. (7) Water cooled turbocharger. (8) Inside bypass line. (9) Water pump. (10) Engine oil cooler. (11) Watercooled exhaust manifold. (12) Water temperature regulator housing. (13) Hot water to heat exchanger.

3116 Heat Exchanger (Sea Water Cooling Circuit)


Sea Water System Schematic
(1) Sea water pump. (2) Heat exchanger (shell assembly). (3) Fuel cooler (if equipped). (4) Marine gear oil cooler. (5) Sea water strainer. (6) Water cooled exhaust elbow. (7) Sea water inlet. (8) Sea water exhaust outlet.

3126 Heat Exchanger (Sea Water Cooling Circuit)


Sea Water System Schematic
(1) Sea water pump. (2) Aftercooler. (3) Heat exchanger (shell assembly). (4) Fuel cooler (if equipped). (5) Marine gear oil cooler. (6) Sea water strainer. (7) Water cooled exhaust elbow. (8) Sea water inlet. (9) Sea water exhaust outlet.

3116 Keel Cooled (Jacket Water Cooling Circuit)


Cooling System Schematic
(1) Shunt line. (2) Expansion tank. (3) Pressure cap. (4) Marine gear oil cooler. (5) Vent lines (air). (6) Shell assembly (lower tank). (7) Keel cooler bypass. (8) Keel cooler. (9) Jacket water aftercooler. (10) Water temperature regulator housing. (11) Cylinder block and cylinder head. (12) Watercooled turbocharger. (13) Water pump. (14) Engine oil cooler. (15) Watercooled exhaust manifold. (16) Keel cooling elbow assembly.

NOTE: In some cases the marine gear oil cooler may be part of an auxiliary sea water pump and transmission oil cooler system.

3126 Keel Cooled (Jacket Water Cooling Circuit)


Cooling System Schematic
(1) Shunt line. (2) Expansion tank. (3) Pressure cap. (4) Vent lines (air). (5) Shell assembly (lower tank). (6) Keel cooler by-pass. (7) Cylinder block and cylinder head. (8) Keel cooler. (9) Water temperature regulator housing. (10) Watercooled turbocharger. (11) Water pump. (12) Engine oil cooler. (13) Watercooled exhaust manifold. (14) Keel cooling elbow assembly.

3126 Keel Cooled (Aftercooler Separate Circuit)


Aftercooler Separate Circuit Schematic
(1) Supply/recovery tank. (2) Pressure cap. (3) Fuel cooler (if equipped). (4) Aftercooler flow control orifice. (5) Separate circuit water pump. (6) Separate circuit keel cooler. (7) Marine gear oil cooler. (8) Aftercooler.

Power Take-Off Group (Front)


Power Take-Off Clutch
(Typical Illustration Rear Clutch Shown)) (1) Ring. (2) Driven discs. (3) Link assemblies. (4) Lever. (5) Key. (6) Collar assembly. (7) Nut. (8) Yoke assembly. (9) Hub. (10) Plates. (11) Output shaft.

Power take-off clutches (PTOs) are used to send power from the engine to accessory components. For example, a PTO can be used to drive an air compressor or a water pump.

The PTO is driven by a ring (1) that has spline teeth around the inside diameter. The ring can be connected to the front or rear of the engine crankshaft by an adapter.

The spline teeth on the ring engage with the spline teeth on the outside diameter of driven discs (2). When lever (4) is moved to the ENGAGED position, yoke assembly (8) moves collar assembly (6) in the direction of the engine. The collar assembly is connected to four link assemblies (3). The action of the link assemblies will hold the faces of driven discs (2), drive plates (10) and hub (9) tight together. Friction between these faces permits the flow of torque from ring (1), through driven discs (2), to plates (10) and hub (9), Spline teeth on the inside diameter of the plates drive the hub. The hub is held in position on the output shaft (11) by a taper, nut (7) and key (5).

NOTE: A PTO can have from one to three driven discs (2) with a respective number of plates.

When lever (4) is moved to the NOT ENGAGED position, yoke assembly (8) moves collar assembly (6) to the left. The movement of the collar assembly will release link assemblies (3). With the link assemblies released there will not be enough friction between the faces of the clutch assembly to permit a flow of torque.

Caterpillar Information System:

SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Power Take-Off Group (Front)
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Auxiliary Water Pump
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Jacket Water Heater
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Water Temperature Regulator
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Electric Starting Motor Solenoid
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Electric Starting Motor
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Regulator
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Alternator
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Sensors Low Coolant Level
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Circuit Breaker
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Magnetic Starter Switch Assembly
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Control Relay
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Testing & Adjusting
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Alternator
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Watercooled Turbocharger
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Watercooled Turbocharger
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Water Temperature Regulator Housing
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Water Temperature Regulator Housing
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Water Temperature Regulator
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Expansion Tank
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Heat Exchanger
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Raw Water Pump
SUPPLEMENT FOR 3116 & 3126 MARINE ENGINE Oil Cooler (Marine Transmission Gear)
3406B INDUSTRIAL & MARINE ENGINES Introduction
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