D399, G399, D398, G398, D379, G379 ENGINES Caterpillar


Air Induction And Exhaust System

Usage:


AIR INDUCTION AND EHAUST SYSTEM
1-Exhaust manifolds. 2-Right cylinder bank. 3-Diffuser plate. 4-Right turbocharger impeller. 5-Exhaust elbow. 6-Left cylinder bank. 7-Turbocharger turbine wheels. 8-Left turbocharger impeller. 9-Aftercooler.

Operation

This engine incorporates two turbochargers. The engine is cross-blown, that is, the right turbocharger furnishes air to the left cylinder bank (6) and the left turbocharger furnishes air to right cylinder bank (2).

Variation in engine load and fuel injected results in changes in speed that the turbine wheels and impellers rotate.

When the turbocharger compresses the inlet air for the engine cylinders, the temperature of the air increases. A water cooled aftercooler (9), installed between the turbochargers and the air inlet manifolds to cylinder banks (2) and (6) will cool and condense the compressed air from the turbochargers. Cooler compressed air has more oxygen, thus more fuel can be injected. When more oxygen is present, more fuel is burned and engine power is increased.

A cast in diffuser plate (3) in the center of exhaust elbow (5) keeps the exhaust from each turbocharger separated to reduce exhaust back pressure.

Turbocharger Removal

Remove bolts (1) and (7) and loosen clamp screw (4) then move the air cleaner away from the turbocharger.

NOTE: At assembly coat mating surfaces of housing and hose with 5H2471 Adhesive before tightening clamp screw (4).


PREPARING TO REMOVE TURBOCHARGER
1-Bolt. 2-Oil inlet line. 3-Oil line. 4-Clamp screw. 5-Oil return line. 6-Bolts (four). 7-Bolts (four).

Remove bolts (6) and loosen clamp screw (11) and remove the turbocharger. At the time of installation apply 9M3710 Anti-Seize Compound and tighten bolts (6) to torque of 36-44 lb. ft. (5,0-6,1 mkg). Again tighten to same torque after engine has completely warmed up.


REMOVING THE TURBOCHARGER
8-Coupling. 9-Pipe. 10-Elbow. 11-Clamp screw.

Proceed in like manner and remove the left turbocharger.


NOTICE

After the turbocharger is removed, cover all the oil and air openinges and store in a clean place until reconditioned or installed.


Turbocharger Installation

Before installing the turbocharger, lubricate the turbocharger shaft with clean crankcase oil through the oil inlet hole and turn the shaft a few turns by hand.

Apply 9M3710 Anti-Seize Compound to bolts fastening oil inlet line (2) to turbocharger.

Install the turbocharger in the reverse order of removal being certain that all connections are tight.

NOTE: The turbocharger requires no special test procedure. However, observe the turbocharger for the initial one-half hour of operation to determine that the unit is secure and that no lubrication leaks develop. Thereafter, periodic checks should be made as outlined in the Lubrication and Maintenance Guide.

Exhaust Manifold - (Water Shielded Type Illustrated)

Removal and Installation


PREPARING TO REMOVE EXHAUST MANIFOLD SHIELD (D399 Illustrated)
1-Governor control support bracket. 2-Bolts. 3-Water inlet box assembly and cross pipe. 4-Fuel injection lines. 5-Elbows (two per cylinder head). 6-Water temperature regulator housing.


DISCONNECTING EXHAUST MANIFOLD SHIELD
7-Bolts. 8-Shield. 9-Shield.

1. Remove the exhaust manifold shield (9).


REMOVING EXHAUST MANIFOLD SHIELD


PREPARING TO REMOVE EXHAUST MANIFOLD
10-Water line. 11-Bolts (four for each turbocharger).

2. Remove the exhaust manifold (shielded type). Approximate weight D399 Engine 165 lbs. (75 kg), D398 Engine 120 lbs. (54 kg) and D379 Engine 90 lbs. (41 kg).


PREPARING TO REMOVE EXHAUST MANIFOLD
12-Bolts (four for each cylinder).

NOTE: At assembly, gasket between head and outer shield should be installed without coating. Apply 9M3710 Anti-Seize Compound to all bolt threads and tighten bolts (12) to a torque of 100-120 lb. ft. (13,8-16,6 mkg). Again tighten after enigne has completely warmed up. Engines with flanged head bolts, tighten to standard bolt torque of 75 ± 10 lb. ft. (10,4 ± 1,4 mkg).


REMOVING THE EXHAUST MANIFOLD

3. Proceed in like manner and remove right exhaust manifold.

4. Replace all gaskets.

5. Install in the reverse order of removal.

Disassembly and Assembly

To replace manifold segments and bellows for cylinders other than end cylinders, it is necessary to remove the end segments and bellows. Thus, progress from one end by removing manifold segment and bellows until the faulty segment or bellows is reached.

1. Loosen clamp (13) and remove segment retaining bolts (14).


MANIFOLD DISASSEMBLY
13-Clamps. 14-Manifold segment retaining bolts. 15-Bellows.

2. Slip the clamp off the bellows. If the manifold segment (16) will not slip out of bellows (15) heat the bellows.


MANIFOLD SEGMENT AND TUBE REMOVED
16-Manifold segment. 17-Tube. 18-Gasket.

Assemble in the reverse order of disassembly.

Apply copper colored 9M3710 Anti-Seize Compound on bolt threads and inside of bellows band at time of assembly. Coat the inside of the clamp bands with molybdenum disulfide fortified lubricant. Heat bellows to ease adjustment of manifold segment position and install new gasket (18) without coating. Tighten retaining bolts (14) to torque of 10 lb. ft. (1,4 mkg). Clamps should be adjusted so both edges of clamp contacts completely around bellows. Tighten 3/8" clamp bolts to torque of 55 ± 3 lb. ft. (7,6 ± 0,4 mkg), 5/16" bolts to torque of 32 ± 3 lb. ft. (4,4 ± 0,4 mkg).


MANIFOLD SEGMENT LOCATION DIAGRAM
19-D379 and G379 Engines. 20-D398 and G398 Engines. 21-D399 and G399 Engines.

Inlet Manifold

Removal and Installation

NOTE: Whenever an inlet manifold is removed, thoroughly clean the inside of the manifold including the elbows, the aftercooler end cover and the inlet air cavities in the cylinder head.


PREPARING TO REMOVE INLET MANIFOLD
1-Inlet manifold elbow. 2-Bolts (six for each cylinder head). 3-Inlet manifold.

Replace the gaskets and O-ring seals on the inlet manifold and install in the reverse order of removal. Apply 9M3710 Anti-Seize Compound on threads of bolts (2).

Aftercooler

The aftercooler is mounted on the top of the flywheel housing. Water, circulated through the aftercooler, cools the air that has been compressed by the turbochargers. Since cooler air is more dense, a greater weight of air will enter the engine cylinders and more fuel can be burned which results in an increase in power.

The aftercooler is constructed so water from the engine cooling system circulates through it to cool the air. The aftercooler assembly can be altered to use auxiliary water as the coolant. When the auxiliary water adapter is used, the baffle in the flywheel housing should be removed so there will be no restriction in the engine fresh water cooling system flow. Sea water should not be used in fresh water cores.

Removal and Installation

1. Remove the air cleaners. See covering topic.

2. Attach a hoist to the aftercooler.


PREPARING TO REMOVE THE AFTERCOOLER
1-Air cleaners. 2-Channel. 3-Left turbocharger pipe. 4-Right inlet manifold elbow. 5-Left inlet manifold elbow. 6-Aftercooler water lines. 7-Right turbocharger pipe.


PREPARING TO REMOVE THE AFTERCOOLER
8-Channel. 9-Bolts (six). 10-Bolts (six).


REMOVING THE AFTERCOOLER
11-Plates (two).

3. Loosen channel (8).

4. Remove sixteen bolts that secure aftercooler to flywheel housing and remove the aftercooler. Approximate weight 175 lbs. (80 kg).

5. Install the aftercooler in reverse order of removal. Be sure plates (11) and gaskets are in place.

NOTE: Before installing the aftercooler make certain the inside is clean. If it is suspected that there are foreign particles in the inlet manifolds, remove and clean them at this time.

Disassembly and Assembly

Sleeves (7) may stay with the core assembly or with the pipes when the crossover pipe (1) or water supply and return pipes are removed.


PREPARING TO DISASSEMBLE AFTERCOOLER
1-Crossover pipe. 2-Channel. 3-Flange (two). 4-Top Housing.

Assemble with new O-ring seals in grooves of sleeves (7) and cores (6). Use new gaskets between housings and flanges (3) and (5) and gaskets (8) between housings and core assemblies.

Blow out air passages with compressed air.


AFTERCOOLER CORE REMOVAL
5-Flange (two). 6-Core assembly (two). 7-Sleeve (four). 8-Gasket (two).

Thoroughly clean the inner surfaces of the housings and adapting pipes.

Assemble in the reverse order of disassembly.

Panel-Type Air Cleaner

The two panel-type air cleaner assemblies each contain a replaceable dry-type filter element (2). The element can be removed and then cleaned with air pressure or by washing. See the Lubrication and Maintenance Guide.

During operation, air enters through the opening in cover (3). Gasket (1) prevents air from flowing around element (2). As the air passes through the filter element, the particles of dirt are trapped in the element. The filtered air passes through outlet (6) and into the turbocharger. Clamps (5) secure the hose (4) to air cleaner outlet and turbocharger inlet thus forming an airtight seal. Hose (4) absorbs vibration between the turbocharger and the air cleaner assembly.


AIR CLEANER AIR FLOW
1-Gasket. 2-Filter element. 3-Cover. 4-Hose. 5-Clamps. 6-Outlets to turbocharger.

Removal and Installation


PREPARING TO REMOVE AIR CLEANER
1-Screw. 2-Bolt. 3-Channel. 4-Bolts (two). 5-Bolts (two).

Support the weight of the air cleaner, weight approximately 50 lbs. (23 kg), remove bolts (2) and (4) and loosen clamp screw (1) and bolts (5) then tip the air cleaner away from the turbocharger. If the hose binds at the turbocharger, remove bolts (5) and pull the air cleaner from the turbocharger. Install the air cleaners in the reverse order of removal.

Install spacers on bolts (4) and (5) to the front of both front and rear channels (3).

NOTE: Whenever a new hose between air cleaner housing and turbocharger is installed, apply 5H2471 Adhesive at the housing-to-hose joint.

Carburetor

Operation

Air enters the carburetor through air horn (3) and fills outer chamber (4). Air enters inner chamber (7) (mixing chamber) by forcing diaphragm assembly (6) away from ring (14). There are two diaphragms, one on each side of the carburetor. Fuel enters the carburetor through fuel inlet (2), past the power mixture adjustment (5) to the center of the carburetor and into fuel outlet tube (9). Fuel valve (12) is mounted on diaphragm assembly (6). With the diaphragm assembly forced away from ring (14), fuel flows past fuel valve (12) and into inner chamber (7). The fuel and air mix in inner chamber (7). This mixture is drawn down past throttle plate (16) and into the inlet manifold.


CARBURETOR OPERATION (Operative position shown)
1-Balance line inlet. 2-Fuel inlet. 3-Air horn. 4-Outer chamber. 5-Power mixture adjustment. 6-Diaphragm assembly (two). 7-Inner chamber. 8-Chamber (two). 9-Fuel outlet tube. 10-Carburetor body. 11-Spring (two). 12-Fuel valve (two). 13-Sensing holes. 14-Ring (two). 15-Idle adjustment opening. 16-Throttle plate.

With the engine stopped, spring (11) holds diaphragm assembly (6) against ring (14) and holds fuel valve (12) closed. No air or fuel can flow to inner chamber (7). As the engine is started, the vacuum in the cylinders, created by the intake stroke of the pistons, creates a low pressure situation in inner chamber (7). This low pressure is sensed by chamber (8), behind the diaphragm assembly, through holes (13). This allows the pressure in chamber (8) to equalize with the low pressure situation in the inner chamber. The higher inlet pressure acting on the outer portion of the diaphragm assembly overcomes the spring force and moves the diagphragm assembly outward. This also moves fuel valve (12) outward and allows air and fuel to flow into the inner chamber. A small volume of air is also metered into the inner chamber through idle adjustment opening (15).

When the engine is operating at a constant RPM, the diaphragms remain in one position. This position is determined by the inlet pressure differential of the gas and air. This pressure differential is maintained by a balance line from the line pressure regulator to the carburetor balance line inlet (1). The pressure differential to the carburetor can be varied by adjusting the line pressure regulator. See the topic, LINE PRESSURE REGULATOR.

Removal and Installation

Shut off the fuel supply to the carburetor.


REMOVING CARBURETOR (G379 Engine Illustrated)
1-Air inlet hose. 2-Balance line. 3-Fuel inlet line. 4-Carburetor. 5-Linkage.

Disassembly and Assembly


CARBURETOR DISASSEMBLY
1-Air horn. 2-Cover (two). 3-Spring (two). 4-Diaphragm assembly (two). 5-Body assembly. 6-Throttle body assembly. 7-Throttle p plate. 8-Lever. 9-Throttle shaft. 10-Seals (two). 11-Bearings (two). 12-Retainer (two). 13-Lever assembly.

1. Remove air horn (1) from body assembly (5).

2. Remove idle adjusting screw and spring from body assembly.

3. Remove the screws which secure throttle plate (7) to shaft (9) and remove shaft. Inspect bearings (11), seals (10), and retainers (12).

4. If installing a new throttle assembly, shaft or lever, pin the lever and shaft together. See the topic, CARBURETOR CONTROL LINKAGE ADJUSTMENT, for correct pinning angle. Drill a .125" dia. hole and through ream for a 2/0 x 1" taper pin.

Adjustments

Turn the power adjustment to center between "R" (rich) and "L" (lean). Fuel mixture adjustments are made by changing the gas pressure from the line pressure regulator. See the topic, LINE PRESSURE REGULATOR.


CARBURETOR ADJUSTMENTS (Carburetor removed for better illustration)
1-Idle adjustment screw. 2-Throttle stop screw.

Turn idle adjustment screw (1) four full turns open (from the closed position).

Turn throttle stop screw (2), to obtain desired idle speed. Recommended low idle is 425 RPM. (750-800 RPM when used with an electric set).

Throttle Valve Synchronization (Engine not operating)

If the throttle valves are not opening simultaneously on both carburetors, the load will not be balanced between the left and right banks of the engine, and uneven operation can result.

1. Disconnect governor linkages at each throttle shaft lever (2).

2. Turn the low idle throttle stop screw (1) out until each throttle will close without allowing the screw to touch the stop. Slots (3) cut in the end of the throttle shaft indicate the position of the throttle plate.

3. Adjust each low idle throttle stop screw (1) so it will just touch the stop with the throttle plate remaining closed. Throttle shaft lever (2) must be in the same relative angular position to the throttle plate [slot (3)] on both carburetors.


THROTTLE VALVE SYNCHRONIZATION (Carburetor removed for better illustration)
1-Low idle throttle stop screw. 2-Throttle shaft lever. 3-Slot.

4. Move the governor control lever to the OFF position.

5. Adjust the length of the governor-to-carburetor linkages so both connections can be made with the throttle plates completely closed, and the governor weights fully closed.

6. Connect both linkages to throttle shaft levers (2).

7. Set both low idle throttle stop screws (1) for the recommended low idle.

Throttle Valve Synchronization (Engine operating)

Check that each regulator is maintaining the required pressure for the fuel being used and that there is equal pressures to both carburetors.

Connect one end of mercury manometer (2) to connection (3) and the other end to the similar connection on the other side of the engine.


BALANCING MANIFOLD PRESSURE
1-Rod. 2-Mercury manometer. 3-Connection. A-Mercury level. B-Mercury level.

The 4S6553 Instrument Group also provides a means to make this quick check. This group contains an instantaneous reading tachometer and a gauge for reading inlet manifold pressure. Special Instructions FE036044 are included with this group.


4S6553 INSTRUMENT GROUP
1-Lid. 2-4S6997 Manifold Pressure Gauge. 3-Pressure tap fitting. 4-4S6992 Differential Pressure Gauges. 5-4S6991 Tachometer. 6-Zero adjustment screws. 7-8M2743 Gauge.

With the engine operating and governor control lever in LOW IDLE SPEED position, adjust length of rods (1). Increase engine speed to full load and check gauge reading. Adjust if necessary. The correct adjustment exists when gauge readings are within 4.1 in. H2O (104,14 mm H2O) or .3 in. Hg (7,62 mm Hg). This is same as difference in mercury level (A) and mercury level (B) in manometer.

NOTE: Do not vary the regulator adjustment to synchronize the inlet manifold pressures. Synchronization is accomplished by linkage adjustment only.

Line Pressure Regulator

A line pressure regulator is required to maintain a constant inlet pressure differential between the gas and air to the carburetor. The pressure differential will vary according to the BTU rating of the gas being used.

Adjustment

1. Line pressure regulator adjustment can be checked with either the 4S6553 Instrument Group or a water manometer while engine is running.

2. Attach one end of a water manometer (4) to the gas supply at carburetor (3). On engines with balance line, attach the other end of the manometer to a tee (1) installed at balance line connection at pressure regulator, or to the air inlet to the carburetor to measure the pressure differential (A). On engines without balance line, attach the manometer only at (3) and leave the other end open to the atmosphere.


CHECKING LINE PRESSURE REGULATOR ADJUSTMENT
A-Positive pressure differential. 1-Tee and manometer connection. 2-Adjustment screw. 3-Gas supply at carburetor. 4-Water manometer. 5-Valve.

NOTE: The valve (5) should be closed before the engine is stopped. This will prevent the manometer fluid from being drawn into the inlet of the carburetor (3).

3. Remove the cap and turn screw (2) until the value (A) is within the specified range. Natural Gas @ 1000 BTU low heat value: 5 in. (127 mm).

Where 2500 BTU low heat value vaporous Propane gas is used, the line pressure regulator should be set to supply 10 in. H2O (254 mm H2O) of gas pressure to the Thermac pressure reducing valve. The Thermac valve will reduce to a negative differential pressure of -1 in. H2O (-25,4 mm H2O). The load adjusting valve in the gas line before the carburetor should be adjusted so the differential pressure is -2 in. H2O (-3,08 mm H2O).


PROPANE GAS REGULATION COMPONENTS

Any other gas specification being used may cause greater or less differential, depending on BTU (LHV) of gas. Special information should be obtained when any other gas is used.

Exhaust Bypass System

The pressure differential regulator (1) serves as an exhaust gas bypass valve. The regulator is mounted on the turbine housing (12). It limits the volume of exhaust gases to the turbine wheel by bypassing a part of the exhaust gases. The exhaust bypass valve (9) is actuated directly by a pressure differential between the atmosphere and turbocharger compressor outlet pressure to the carburetor.


EXHAUST BYPASS SYSTEM
1-Pressure differential regulator. 2-Air inlet pipe. 3-Exhaust manifold. 4-Carburetor. 5-Turbocharger. 6-Regulator control line connection.

One side of the diaphragm (13) in the regulator senses atmospheric pressure through a breather in the top of the regulator at breather location (10). The other side of the diaphragm senses air pressure from the turbocharger compressor outlet side through a control line connected at (6). When outlet pressure to the carburetor reaches the proper value, the force of the air pressure upon the diaphragm overcomes the force of the spring (8) and atmospheric pressure. This force unseats the bypass valve, allowing exhaust gases to bypass the turbine wheel.


REGULATOR OPERATION
6-Regulator control line connection. 7-Spacers. 8-Spring. 9-Bypass valve. 10-Breather location. 11-Bypass passage. 12-Turbine housing. 13-Diaphragm. 14-Shims.

The bypass passage (11) is located inside the turbine housing (12). Under steady load conditions, the valve will assume a fixed position, allowing just enough exhaust gas to the turbine wheel to maintain the proper outlet pressure to the carburetor (4).

The regulator has two .25 in. (6,4 mm) spacers (7) for altitude adjustment. Both spacers should be used for operation up to 1500 feet (457,2 m) altitude. Remove one for operating between 1500 and 4000 feet (457,2 - 1219,2 m), and remove both for operation above 4000 feet (1219,2 m). Slight amount of adjustment can be made by adding or removing shims (14). The regulator assembly bolts should be sealed at assembly.

To test the regulator with both spacers (7) in place, and atmospheric pressure in spring compartment, apply 6.65 - 7.20 PSI (0,47 - 0,51 kg/cm2) to pressure chamber through connection (6). Measurement from valve (9) face to body mounting face should be 2.893 in. (73,48 mm).

NOTE: Information in Form FE034610 shows equipment for testing and adjusting this regulator.

Caterpillar Information System:

D399, G399, D398, G398, D379, G379 ENGINES Line Pressure Regulator
D399, G399, D398, G398, D379, G379 ENGINES Magneto Drive
D399, G399, D398, G398, D379, G379 ENGINES Governor Drive/(Natural Gas Engines)
D399, G399, D398, G398, D379, G379 ENGINES Fuel Pump And Governor Drive
D399, G399, D398, G398, D379, G379 ENGINES Ignition
D399, G399, D398, G398, D379, G379 ENGINES Safety Shutoff Control
D399, G399, D398, G398, D379, G379 ENGINES Fuel Injection Equipment
D399, G399, D398, G398, D379, G379 ENGINES Fuel Supply Equipment
D399, G399, D398, G398, D379, G379 ENGINES Fuel System
D399, G399, D398, G398, D379, G379 ENGINES Sump Pump
D399, G399, D398, G398, D379, G379 ENGINES Oil Filters
D399, G399, D398, G398, D379, G379 ENGINES Oil Cooler
D399, G399, D398, G398, D379, G379 ENGINES Turbocharger
D399, G399, D398, G398, D379, G379 ENGINES Turbocharger
D399, G399, D398, G398, D379, G379 ENGINES Turbocharger
D399, G399, D398, G398, D379, G379 ENGINES Turbocharger
D399, G399, D398, G398, D379, G379 ENGINES Cylinder Heads - (Natural Gas Engines)
D399, G399, D398, G398, D379, G379 ENGINES Cylinder Heads (Diesel Engines)
D399, G399, D398, G398, D379, G379 ENGINES Valves And Valve Mechanism
D399, G399, D398, G398, D379, G379 ENGINES Vibration Damper
D399, G399, D398, G398, D379, G379 ENGINES Timing Gears
D399, G399, D398, G398, D379, G379 ENGINES Front Accessory Drive
D399, G399, D398, G398, D379, G379 ENGINES Basic Block Components
D399, G399, D398, G398, D379, G379 ENGINES Balancer - (D379 Only)
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