3176B Marine Engine Caterpillar

• Four stroke cycle

• Direct fuel injection

• Turbocharged

• Raw/seawater aftercooled or separate circuit aftercooling

The electronic control module (ECM) provides the following benefits:

• Engine monitoring

• Electronic governing

• Automatic air/fuel ratio control

• Torque rise shaping

• Injection timing control

• System diagnostics

Additional benefits provide the following advantages: additional engine fuel economy, operator comfort and serviceability. The additional benefits that follow are provided by the ECM: improved cold starting capability, resistance to tampering, diagnostics and optional Engine Monitoring Package. The engine is equipped with electronic unit injectors in order to combine the pumping and electronic fuel metering. This produces very high injection pressures. The electronic unit injectors have full authorization over the fuel delivery in order to accurately control smoke limiting, white smoke and engine acceleration rates. The timing advance is achieved by the precise control of the electronic unit injector. Engine load is controlled by adjusting the firing duration. A speed/timing sensor provides information to the fuel cooled ECM. The information is used for detection of cylinder position and engine speed.

The fuel is metered and pumped under high pressure with the Electronic Unit Injector (EUI). There is one electronic unit injector for each cylinder. High injection pressures help to reduce fuel consumption and emissions. The use of this type of unit fuel injector provides total electronic control of injection timing. The injection timing is varied as a function of engine operating conditions. This optimizes the engine's performance for starting, emissions, noise and fuel consumption.

Built-in diagnostics ensure that all components are functioning and operating properly. The operator will be alerted if a system component deviated from the set limits. A dash mounted diagnostic lamp is used in order to alert the operator. A Caterpillar service tool or a toggle switch (if equipped) may be used in order to read the diagnostic flash codes. There are three types of diagnostic codes: active, logged and event. These codes are logged and stored in the system memory. Refer to the Operation and Maintenance Manual, "Engine Diagnostics" section of this publication for additional information.

The ECM controls the output of the electronic unit injector. This will maintain the desired engine rpm. There is some droop. The ECM has a programmable low idle rpm of 600 to 750 rpm. The programmable low idle rpm is regardless of load. The electronic governor eliminates most of the overrun (20 to 200 rpm governor overrun) at high idle that is experienced with a mechanical governor.

The 3176B does not have a cylinder block water cooling system. Instead, the cast water manifold in the spacer deck distributes 65 percent of the coolant volume to each of the cylinder liners and the remaining 35 percent flows directly to the cylinder head.

The engine lubricating oil is cooled and filtered. The engine lubricating oil is supplied by a gear type pump. Bypass valves provide unrestricted flow of lubrication oil to the engine parts when oil viscosity is high, or if either the oil cooler or the oil filter elements (paper cartridge) should become plugged.

The engine is equipped with a SAE No. 1 flywheel housing in order to mate with various marine gears. Several manufacturers of marine gear offer marine transmissions for the engines through the local distributors.

The jacket water cooling system incorporates a heat exchanger and an expansion tank. The water cooled exhaust manifolds, risers and turbochargers are designed to minimize radiated heat in the engine room. Another cooling system feature is the use of a raw water pump. The raw water pump increases cooling capacity to the aftercooler.

The 3176B Marine Engine uses a closed crankcase emissions system which eliminates crankcase vapors in the engine room. The closed crankcase emissions system routes vapor back through the air cleaner into the combustion system.

Marine Transmissions

Several manufacturers offer marine transmissions through local distributors. Lubrication oil for the marine transmission can be cooled by an optional engine mounted transmission oil cooler (certain engine ratings).

Engine Service Life

Engine efficiency and maximum utilization of engine performance depend on the adherence to proper operation and maintenance recommendations. In addition, use recommended fuels, coolants, and lubricants. Use the Operation and Maintenance Manual as a guide for required engine maintenance.

Expected engine life is generally predicted by the average power that is demanded. Engine life is also based on fuel consumption of the engine over a period of time. Reduced hours of operation at full throttle and/or operating at reduced throttle settings result in a lower average power demand. Reduced hours of operation will increase the length of operating time before an engine overhaul is required. See the Operation and Maintenance Manual for more information.

Engine Specifications

Illustration 1	g00275578
(A) Exhaust valves (B) Inlet valves