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SERIES 50 AIR COMPRESSOR

The Series 50 air compressor is flange mounted to the air compressor drive assembly, located on the left side of the engine at the rear of the gear case. See Figure 20544 . ‪

Air Compressor Mounting

Detroit Diesel has improved the mounting of the air compressor coolant inlet hose which runs from the cylinder block to the air compressor. The improved mounting eliminates the potential for air compressor coolant hose abrasion caused by rubbing against the cylinder block. ‪

To eliminate abrasion caused by rubbing of the coolant inlet hose against the cylinder block, a new mounting clip (23506443) and bolt (11503454) are now used on all engines with Bendix air compressors. ‪

Original air compressors were flange-mounted to the air compressor drive assembly. See Figure 25213 . Effective with unit serial number 4R6959 built November 22, 1994, adaptorless air compressors replaced the original compressors on the majority of Series 50 engines. Adaptorless compressors are flange-mounted directly to the gear case. See Figure 24590 . Improved cylinder blocks were released concurrent with this change. The adaptorless air compressors can only be used with the improved cylinder blocks. Refer to Section for information on the improved cylinder blocks. ‪

Adaptorless Air Compressor Mounting

Location of Air Compressor Pressure Relief Valve

This air compressor also drives the engine fuel pump which is bolted to the rear end of the compressor. The compressor crankshaft is designed to accept a drive coupling placed between the compressor and fuel pump. ‪

The compressor is driven by the bull gear. The air compressor is water cooled. Engine coolant is fed to the compressor through a flexible hose tapped into the engine block water jacket and connected to the front of the compressor. Coolant returns from the rear of the compressor through a flexible hose to the engine cylinder head. Lubricating oil is supplied to the compressor by a line from the cylinder block oil gallery that connects to the air compressor. Lubricating oil returns to the engine crankcase through the air compressor drive assembly. The Series 50 air compressor is unique compared to the DDC two cycle engines because of its special forged crankshaft, drive hub, and nut. ‪

Replacement of Air Compressor

Detroit Diesel does not service the air compressor. Service of air compressors should be referred to an authorized service center of the original equipment manufacturer. ‪

To replace the air compressor, perform the following procedure. See Figure 21744 . ‪

Flowchart for Replacement of Air Compressor

Cleaning and Removal of Air Compressor

Pre-cleaning is not necessary. ‪

Remove the air compressor as follow: ‪

  1. Disconnect the air lines to and from the compressor.
  2. Disconnect the fuel pump lines.
  3. Remove the fuel pump and drive coupling. Refer to Section .
  4. Drain the cooling system. Refer to Section .
  5. Disconnect and remove the coolant supply line hose and clip and return lines at the air compressor.
  6. Disconnect the lubricating oil supply line from the compressor.
  7. Remove an unused compressor discharge port plug on the top or side of the compressor head, if necessary for installation of a pressure relief valve.
  8. Remove the bolts securing the air compressor support bracket from the cylinder block and air compressor.
  9. Remove the support bracket.

    Note: Due to the cylinder block and compressor configuration, the upper inside air compressor-to-air compressor drive bolt is difficult to reach with standard tools. Compressor wrench, J 35948 , will facilitate removal and installation of this bolt.

  10. Remove the bolts that secure the air compressor to the air compressor drive assembly.
  11. Slide the air compressor rearward to disengage the hub from the coupling.

Inspection of Air Compressor

Refer to OEM guidelines to determine if the air compressor needs to be repaired or replaced. ‪

Installation of Air Compressor

Install the air compressor as follows: ‪

  1. Clean all gasket material from the mating surfaces of the air compressor and air compressor drive.
  2. Using a new gasket, install the air compressor as follows:
    1. Adaptor-mounted compressor: mate the internal gear teeth of the drive assembly hub with the external gear teeth of the coupling.
    2. adaptorless compressor: mate the external gear teeth of the compressor coupling with the bull gear teeth.
  3. Install the pressure relief valve into the open discharge port plug. Using a 7/8 in. (Number 14 metric) deep socket, carefully torque the valve to 23-31 Nm (17-23 lbft).
  4. Align the bolt holes of the two components and install the air compressor-to-air compressor drive bolts.
  5. Torque the five bolts and one nut to 5873 Nm (4354 lbft) using the required torque pattern. See Figure 40083 . Use compressor wrench, J 35948 , to tighten the upper-inside bolt.

    Note: The shorter bolt is installed in the two o'clock position.

    Bolt Torque Sequence

  6. Install the air compressor support bracket to the compressor and cylinder block. Tighten the support bracket-to-air compressor bolts.
    1. For 25 mm long bolts use a torque of 4152 Nm (3038 lbft).
    2. For 20 mm long bolts use a torque of 3038 Nm (2228 lbft).
  7. Torque the support bracket-to-cylinder block bolts to 58-73 Nm (43-54 lbft).
  8. If spring type hose clamps are used:
    1. Install the coolant supply and return lines from the cylinder block and connect to the air compressor using four spring type hose clamps. Torque to 58-73 Nm (43-54 lbft).
    2. Install the supercharger line from the intake manifold and connect to the air compressor using two spring type hose clamps.
  9. If a worm screw drive, liner type clamp is used:
    1. Install the coolant supply and return lines from the cylinder block and connect to the air compressor using four worm screw drive clamps. Torque to 58-73 Nm (43-54 lbft).
    2. Install the supercharger line from the intake manifold and connect to the air compressor using two worm screw drive type hose clamps.
  10. Install the lubricating oil supply line to the compressor.
  11. Install the air lines to and from the compressor.
  12. If the unit has a compressor driven fuel pump, install the fuel pump. Refer to Section .
  13. Refer to Section to fill the cooling system.