Series 50 – Section 1.11 Gear Case

Section 1.11
Gear Case

The gear case housing is constructed of cast iron, with machined mating surfaces, and is bolted to the front of the engine cylinder block. The gear case and gear case cover are bolted together to provide a sealed compartment for the engine gear train. See Figure "Gear Case and Related Parts" .‪

Figure 1. Gear Case and Related Parts

In July 2001,a new right side gear case stiffening bracket was added to provide: reduce engine noise, increase belt-driven accessory life, reduce gear case vibration amplitude and reduce wear on the cam thrust plate perimeter seal. See Figure "Gear Case Stiffening Bracket (Right Side)" .‪

Figure 2. Gear Case Stiffening Bracket (Right Side)

Several components are mounted to the gear case, including the adjustable idler gear assembly. See Figure "Adjustable Idler Gear Assembly" . The camshaft drive gear assembly, see Figure "Camshaft Drive Gear Assembly" ; the air compressor drive assembly, see Figure "Air Compressor Drive Assembly" ; and the water pump assembly, see Figure "Water Pump Assembly" . ‪

1. Gear Case Housing‪	5. Adjustable Idler Gear‪
2. Diamond Dowel‪	6. Adjustable Idler Hub‪
3. Adjustable Idler Gear Locknut (3)‪	7. Adjustable Idler Gear Stud (3)‪
4. Adjustable Idler Gear Hub Retaining Plate‪	8. Round Dowel‪

Figure 3. Adjustable Idler Gear Assembly

1. Bolt, Thrust Plate Retaining (2)‪	6. Gear Case‪
2. Bolt, Camshaft Hub Retaining‪	7. Seal, Thrust Plate‪
3. Drive Gear, Camshaft‪	8. Camshaft‪
4. Thrust Plate, Camshaft‪	9. Key‪
5. O-ring‪	10. Hub‪

Figure 4. Camshaft Drive Gear Assembly

1. Air Compressor Drive Housing‪	8. Air Comp. Drive Hub Flange Nut‪
2. Washers‪	9. Air Comp. Drive Housing Long Bolt‪
3. Air Compressor Drive Housing Short Bolt‪	10. Air Compressor Drive Shaft‪
4. Air Compressor Drive Ball Bearing‪	11. Air Comp. Drive Gear‪
5. Snap Ring‪	12. Air Comp. Drive Gear Bolt‪
6. Spacer‪	13. Air Compressor Drive Housing Gasket‪
7. Air Compressor Drive Hub‪	14. Gear Case Housing‪

Figure 5. Air Compressor Drive Assembly

1. Retaining Bolt‪	10. Water Pump Housing‪
2. Washer‪	11. Pipe Plug‪
3. Water Pump Drive Gear‪	12. Water Pump Housing Retaining Bolt‪
4. Snap Ring‪	13. Water Seal‪
5. Bearing Race Assembly‪	14. Impeller‪
6. Drive Shaft‪	15. Water Pump Cover O-ring‪
7. Oil Seal‪	16. Water Pump Cover‪
8. Water Pump Housing O-ring‪	17. Water Pump Cover Snap Ring‪
9. Drain Cock‪	‪

Figure 6. Water Pump Assembly

To eliminate the possibility of oil leakage at the adjustable idler gear stud location, Detroit Diesel recommends the following:‪

When rebuilding a Series 50 Engine, or if the gear case is removed for any reason, the three original adjustable idler gear studs should be removed and replaced with new studs.‪

Before pressing studs into the gear case, coat the shanks and underside of the stud heads with Loctite No. 242 Sealant . This will prevent any oil leakage around the studs during engine operation.‪

The Timing Reference Sensor (TRS) is an electronic component that is bolted to the side of the gear case on the intake (left) side of the engine just above the oil pan. See Figure "Timing Reference Sensor (TRS)" . ‪

Figure 7. Timing Reference Sensor (TRS)

The Synchronous Reference Sensor (SRS) is an electronic component that is bolted to the gear case at the lower, intake (left) side of the engine. See Figure "Synchronous Reference Sensor" .‪

Figure 8. Synchronous Reference Sensor

An opening is provided in the center of the gear case, for the bull gear and camshaft idler gear assembly, which bolts directly to the engine block. See Figure "Bull Gear and Camshaft Idler Gear Assembly" .‪

Figure 9. Bull Gear and Camshaft Idler Gear Assembly

An access cover is provided at the rear of the gear case on the cooler (right) side of the engine. This access cover provides an opening for inspection of the accessory drive assembly drive gear. See Figure "Accessory Drive Assembly Drive Gear Access Cover" .‪

Note: This access cover opening may be cast closed on the rear of the gear case.

Figure 10. Accessory Drive Assembly Drive Gear Access Cover

Gear lash measurement and adjustment procedures for the gears in the engine gear train. Refer to "1.21.2.1 Check Engine Timing" .‪

Note: Do not use the oil plug location for oil supply or for checking oil pressure.

An oil gallery is drilled in the gear case casting, for lubrication of the adjustable idler gear assembly. A hole in the front of the cylinder block, indexes with the gear case gallery. At the edge of the gear case the gallery is threaded for insertion of a plug. An exit hole feeds the adjustable idler gear assembly. See Figure "Adjustable Idler Gear Lubrication Gallery" . ‪

Figure 11. Adjustable Idler Gear Lubrication Gallery

Section 1.11.1
Repair or Replacement of Gear Case

To determine if repair is possible or replacement is necessary perform the following procedure. See Figure "Flowchart for Repair or Replacement of Gear Case" .‪

Figure 12. Flowchart for Repair or Replacement of Gear Case

Section 1.11.2
Removal of Gear Case

To remove the gear case:‪

1. Remove the SRS. Refer to "2.20.2 Removal of Synchronous Reference Sensor" .
2. Remove the TRS from the gear case to prevent their damage on removal of the gear case. Refer to "2.21.2 Removal of Timing Reference Sensor" .
3. Remove the rocker arm assemblies. Refer to "1.3.2 Removal of Rocker Arm Assembly" .
4. Perform all of the steps for camshaft removal; refer to "1.22.2 Removal of Camshaft and Camshaft Bearing" .
5. Remove the 3 bolts that secure the camshaft gear pilot tool, J 35906 , to the gear case and remove the tool.
6. Remove the two bolts securing the right side gear case stiffening bracket. See Figure "Gear Case Stiffening Bracket (Right Side)" .
   

   Figure 13. Gear Case Stiffening Bracket (Right Side)

7. Refer to "1.10.2 Removal of Gear Case Cover" , for case cover removal and perform the steps up to but not including, supporting the gear case cover with a suitable lifting device. For the final step, refer to step 15 . See Figure "Gear Case Cover Removal" .
   

   Figure 14. Gear Case Cover Removal

8. Remove the fuel pump from the fuel pump drive assembly (or air compressor). Refer to "2.5.2 Removal of Fuel Pump" .
9. Remove the air compressor. Refer to "10.1.2 Cleaning and Removal of Air Compressor" .
10. Remove the air compressor drive assembly. Refer to "10.2.2 Cleaning and Removal of Air Compressor Drive Hub" .
11. Install the crankshaft protector, J 35994 , to the oil seal contact area of the crankshaft. This will help to protect the crankshaft seal surface when removing the bull gear and camshaft idler gear assembly. See Figure "Crankshaft Protector Installation" .
    

    Figure 15. Crankshaft Protector Installation

12. Remove the bull gear and camshaft idler gear assembly from the engine. Refer to "1.26.2 Removal of Bull Gear and Camshaft Idler Gear Assembly" .
13. Remove the adjustable idler gear assembly from the gear case. Refer to "1.25.2 Removal of Adjustable Idler Gear Assembly" .
14. Using a plastic hammer or fiber mallet, tap the rear face of the camshaft thrust plate to remove the thrust plate, camshaft drive gear hub and camshaft drive gear from the gear case.
15. Remove the 12 bolts that secure the gear case to the engine block. See Figure "Gear Case Mounting Bolt Locations" . Also remove the bolt that secures the gear case stabilizer bracket to the gear case.
    

    Figure 16. Gear Case Mounting Bolt Locations

16. Using a leather or cloth-wrapped strap, support the gear case. See Figure "Gear Case Removal" .
    

    Figure 17. Gear Case Removal

17. Use a rubber hammer or plastic mallet to loosen the gear case from the cylinder block dowels.

Section 1.11.2.1
Inspection of Gear Case

Clean all of the old gasket sealer from the mating surfaces of the gear case, gear case cover and engine block. Clean the gasket material from the mating surfaces of any components or access covers that were removed from the gear case cover or gear case.‪

EYE INJURY ‪
To avoid injury from flying debris when using compressed air, wear adequate eye protection (face shield or safety goggles) and do not exceed 276 kPa (40 psi) air pressure.‪

Clean all of the parts with clean fuel oil and dry with compressed air. Remove the oil gallery plug at the edge of the gear case. See Figure "Adjustable Idler Gear Lubrication Gallery" . Use compressed air to ensure the oil gallery is completely free of blockage. If necessary, use a wire brush to clean the gear case oil gallery.‪

Inspect the gear case for stress cracks, breaks, or other damage. Repair or replace as necessary. Inspect the adjustable idler gear studs for signs of galling or scoring. Replace as necessary. Inspect all the individual components as outlined under the appropriate section.‪

Section 1.11.3
Installation of Gear Case

Use the following instructions for gear case installation:‪

Note: The installation of Gasket Eliminator to the gear case-to-block mating surfaces at the top of the block is critical. Excess gasket eliminator material can extrude into the oil passage between the block and gear case, causing early failure of components. In addition, the bull gear recess area MUST be cleaned of any and all foreign material after installation of the gear case to the engine block.

1. Apply a thin film of gasket eliminator PT-7276 (Loctite 51580) or equivalent to the cylinder block. See Figure "Gasket Eliminator Application (Cylinder Block)" . Carefully smooth the bead around the block-to-gear case oil passage to avoid contamination.
   

   Figure 18. Gasket Eliminator Application (Cylinder Block)

2. Insert Gear Case Alignment Plug, J 35651 , into the bull gear and camshaft idler gear hub recess in the cylinder block. See Figure "Gear Case Alignment Plug" .
   

   Figure 19. Gear Case Alignment Plug

3. Using a suitable lifting sling made of cloth or leather, position the bull gear and camshaft idler gear opening of the gear case over the gear case alignment plug. Index the hole in the gear case mating surface with the diamond dowel at the lower left corner of the cylinder block. See Figure "Cylinder Block Locating Dowel" .
   

   Figure 20. Cylinder Block Locating Dowel

4. With the gear case alignment plug fully seated, the gear case centered on the alignment plug and the diamond dowel in the cylinder block indexed with its mating hole in the gear case, the gear case is positioned properly for bolt installation. See Figure "Gear Case Positioning" .
   

   Figure 21. Gear Case Positioning

   Note: Gasket Eliminator cures with the absence of air. The time between the installation of the gear case, and torquing of the bolts that secure the gear case to the cylinder block should be kept to a minimum.

5. Install the 12 gear case-to-cylinder block retaining bolts, finger-tighten.
6. See Figure "Gear Case Bolt Torque Sequence" , and torque the gear case-to-cylinder block bolts to 58-73 N·m (43-54 lb·ft) using the sequence shown.
   

   Figure 22. Gear Case Bolt Torque Sequence

7. Remove the gear case alignment plug from the gear case.
8. Install the air compressor. Refer to "10.1.4 Installation of Air Compressor" .
9. Install the air compressor drive assembly. Refer to "10.3.5 Installation of Air Compressor Drive Assembly" .
10. Install the fuel pump to gear case. Refer to "2.5.5 Installation of Gear Train-Driven Fuel Pump" .
11. Refer to "4.2.7 Installation of Water Pump" and install the water pump assembly.
12. Lubricate the rubber O-ring on the camshaft thrust plate with clean engine oil. Install the camshaft thrust plate assembly, with the camshaft drive gear and hub in place to the gear case, using a plastic hammer or fiber mallet to tap the thrust plate rearward in the gear case just enough to start it in the gear case. See Figure "Camshaft Thrust Plate Installation" .
    

    Figure 23. Camshaft Thrust Plate Installation

13. Install the adjustable idler gear assembly to the gear case. Refer to "1.25.3 Installation of Adjustable Idler Gear Assembly" . Align the timing marks of the adjustable idler gear and camshaft drive gear. See Figure "Engine Gear Train Timing Marks" .
    

    1. Camshaft Idler Gear‪	4. Bull Gear‪
    2. Adjustable Idler Gear‪	5. Crankshaft Timing Gear‪
    3. Camshaft Drive Gear‪	‪

    Figure 24. Engine Gear Train Timing Marks

14. Inspect the bull gear and camshaft idler gear access opening in the gear case and remove any foreign material.
15. Install two bull gear guide studs, J 35785 to the cylinder block. See Figure "Bull Gear Guide Stud Installation" .
    

    Figure 25. Bull Gear Guide Stud Installation

16. Install the crankshaft protector, J 35994 , to the oil seal contact area of the crankshaft. This will help to protect the crankshaft seal surface when installing the bull gear and camshaft idler gear assembly.

    NOTICE:
    Always install crankshaft protector when installing the bull gear and camshaft idler gear assembly to prevent damaging the crankshaft oil seal contact surface.‪

17. Install the bull gear and camshaft idler gear assembly to the guide studs. Align the timing marks on the bull gear and the crankshaft timing gear and the camshaft idler gear and adjustable idler gear; see Figure "Engine Gear Train Timing Marks" , and slide the bull gear and camshaft idler gear assembly forward to seat it in the recess in the gear case and cylinder block.
18. Working through the lightening holes in the bull gear, install two of the bull gear assembly mounting bolts through the hub and into the cylinder block. Tighten the bolts finger tight.
19. Remove the two bull gear guide studs. Install the remaining two bull gear assembly mounting bolts. Torque the bolts to 101-126 N·m (75-93 lb·ft). Tighten in a clockwise sequence.
20. Check the timing marks on the gears to ensure the gear train is properly timed. See Figure "Engine Gear Train Timing Marks" .
21. Perform the following:
    1. Crankshaft timing gear-to-oil pump idler gear lash measurement. Refer to "1.21.2.1 Check Engine Timing" , step 2 .
    2. Crankshaft timing gear-to bull gear lash measurement. Refer to "1.21.2.1 Check Engine Timing" , step 3 .
    3. Refer to "1.10.3 Installation of Gear Case Cover" for gear case cover installation.
    4. Install the bolt securing the right side gear case stiffening bracket to the gear case first and torque to 74.57–81.35 N·m (55–60 lb·ft). Then install the bolt attaching bracket to the cylinder head and torque to 58.30–73.21 N·m (43–54 lb·ft). See Figure "Gear Case Stiffening Bracket (Right Side)" .
       

       Figure 26. Gear Case Stiffening Bracket (Right Side)

22. Refer to "1.22.5 Installation of Camshaft and Camshaft Bearing" , "Installation of Camshaft and Camshaft Bearings" and perform the necessary steps.
23. Refer to "1.21.2.1 Check Engine Timing" for bull gear-to-accessory pulley drive gear lash measurement and perform step 10 .
24. If the former stabilizer bracket has not been removed, loosen the two bolts securing the bracket to the cylinder head. Install the gear case stabilizer bracket-to-gear case bolt and torque to 58-73 N·m (43-54 lb·ft). Then, retighten the stabilizer bracket-to-cylinder head bolts to 58-73 N·m (43-54 lb·ft) torque.
25. Continue engine assembly.