0325828 JOHNSON ORIFICE,Idle lower carburetor

Engine Specifications
The front end of the engine is opposite the flywheel end of the engine. The left and the right sides of the engine are determined from the flywheel end. The number 1 cylinder is the front cylinder.
Illustration 1 g01187485
(A) Exhaust valves
(B) Inlet valves
Table 1
C4.4 Engine Specifications
Operating Range (rpm) 800 to 2200 (1)
Number of Cylinders 4 In-Line
Bore 105 mm (4.13 inch)
Stroke 127 mm (4.99 inch)
Power Single turbocharger charge cooled
66 to 110 kW (88.506 to 147.51 hp)
Series turbochargers charge cooled
105 to 129.5 kW (140.80 to 173.65 hp)
Aspiration Single Turbocharged charge cooled
Series turbochargers charge cooled
Compression Ratio 16.5:1
Displacement 4.4 L (268.504 cubic inch)
Firing Order 1-3-4-2
Rotation (flywheel end) Counterclockwise
(1) The operating rpm is dependent on the engine rating, the application, and the configuration of the throttle.Electronic Engine Features
The engine operating conditions are monitored. The Electronic Control Module (ECM) controls the response of the engine to these conditions and to the demands of the operator. These conditions and operator demands determine the precise control of fuel injection by the ECM. The electronic engine control system provides the following features:
Engine monitoring
Engine speed governing
Control of the injection pressure
Cold start strategy
Automatic air/fuel ratio control
Torque rise shaping
Injection timing control
System diagnostics
Low temperature regenerationFor more information on electronic engine features, refer to the Operation and Maintenance Manual, "Features and Controls" topic (Operation Section).Engine Diagnostics
The engine has built-in diagnostics in order to ensure that the engine systems are functioning correctly. The operator will be alerted to the condition by a "Stop or Warning" lamp. Under certain conditions, the engine horsepower and the vehicle speed may be limited. The electronic service tool may be used to display the diagnostic codes.There are three types of diagnostic codes: active, logged and event.Most of the diagnostic codes are logged and stored in the ECM. For additional information, refer to the Operation and Maintenance Manual, "Engine Diagnostics" topic (Operation Section).The ECM provides an electronic governor that controls the injector output in order to maintain the desired engine rpm.Engine Cooling and Lubrication
The cooling system and lubrication system consists of the following components:
Gear-driven centrifugal water pump
Water temperature regulator which regulates the engine coolant temperature
Gear-driven rotor type oil pump
Oil coolerThe engine lubricating oil is supplied by a rotor type oil pump. The engine lubricating oil is cooled and the engine lubricating oil is filtered. The bypass valve can provide unrestricted flow of lubrication oil to the engine if the oil filter element should become plugged.Engine efficiency, efficiency of emission controls, and engine performance depend on adherence to proper operation and maintenance recommendations. Engine performance and efficiency also depend on the use of recommended fuels, lubrication oils, and coolants. Refer to this Operation and Maintenance Manual, "Maintenance Interval Schedule" for more information on maintenance items.Aftertreatment System
The aftertreatment system is approved for use by Caterpillar. In order to be emission-compliant only the approved Caterpillar aftertreatment system or approved components must be used on a Caterpillar engine.Clean Emission Module (CEM)
The function of the CEM is to ensure that the engine exhaust meets the required emissions regulation for the country of operation.There are two configurations of the CEM.
Diesel Oxidation Catalyst (DOC) and Selective Catalytic Reduction (SCR)
Diesel Oxidation Catalyst (DOC) Diesel Particulate Filter (DPF) and Selective Catalytic Reduction (SCR)For the DOC and SCR aftertreatment configurations the CEM is comprised of three main components: The Diesel Oxidation Catalyst (DOC), the mixer and the Selective Catalytic Reduction Catalyst (SCR).The engine is connected by a flexible pipe to the CEM. The exhaust gases pass through the DOC and then the mixer where the gases are mixed with the injected urea. The mixture then enters the SCR catalyst. Here the NOx in the exhaust reacts with the ammonia from the injected urea to split the gases into nitrogen and oxygen constituents. The SCR catalyst includes an ammonia oxidation section (AMOX) to clean up any remaining ammonia before the gases exit the system.For the DOC, DPF and SCR aftertreatment configurations the CEM has four main components again: DOC and Diesel Particulate Filter (DPF) in the first unit, the mixer, and the SCR.In this instance the only differences to the operation described above is that the particulate matter soot and ash are trapped by the DPF. A passive regeneration process is used to ensure that normal operation of the engine removes the soot. The ash remains in the DPF and must be removed at an engine overhaul.Cooling and Purging of the DEF Lines
After key-off, the DEF pump will circulate the DEF fluid for a given time, in order to cool the DEF injector. Also, the DEF pump will purge the DEF system of fluid to protect the system from freeze of the DEF fluid in cold conditions.With the DOC and SCR aftertreatment system the cooling and purging will take a minimum of 3 minutes and a maximum of 10 minutes. The time taken will depend on the temperature with the aftertreatment system.When the DOC, DPF and SCR system is operating with exhaust gas temperatures below 425° C (797° F) before key-off, the cooling and purging will also take 6 minutes. When the DOC, DPF, and SCR aftertreatment system operates at temperatures above 425° C (797° F), and key-off occurs the cooling and purging will take a maximum of 15 minutes.For example, the maximum cool-down and purge time is only likely to be encountered in a certain combination. Full-load rated speed operation and the DPF in a regeneration mode occurring simultaneously, immediately before key-off. Engine Service Life
Engine efficiency and maximum utili