The air compressor drive assembly mounts to the rear of the gear case on the intake side of the engine. See Figure
1. Plain Washers (Shims)
8. Flange Nut, Air Compressor Drive Hub
2. Short Bolt, Air Compressor Drive Housing-to-Gear Case (1)
9. Plain Washers (Shims) Long Bolt
3. Housing, Air Compressor
10. Shaft, Air Compressor Drive
4. Ball Bearing, Air Compressor Drive
11. Gear, Air Compressor Drive
5. Snap Ring
12. Bolt, Air Compressor Drive Gear-to-Shaft
13. Gasket, Air Compressor Drive Housing-to-Gear Case
7. Hub, Air Compressor Drive
14. Drive Gear Case
Air Compressor Drive Detail and Location of Parts
A drive gear meshes with the bull gear and is driven at a ratio of 1.19:1.
The drive gear is bolted to the air compressor drive shaft. A drive hub is installed onto the opposite end of the air compressor drive shaft, and is used to drive the air compressor. On vehicles with power steering, a short splined coupling connects the drive gear to the power steering pump. The coupling is inserted in the splined center of the air compressor drive gear.
Two composition gaskets are used, one to seal the air compressor drive housing to the gear case, and one to seal the air compressor to the drive housing.
Replacement of Air Compressor Drive Assembly
To replace the air compressor drive assembly, perform the following procedure. See Figure
Flowchart for Replacement of Air Compressor Drive Assembly
Cleaning and Removal of Air Compressor Drive Assembly
Install the flanged nut retaining the drive hub to the drive shaft. Torque the nut to 300-345 Nm (221-255 lbft).
Remove the drive assembly from the holding fixture and position it on a suitable flat surface with the drive gear facing up.
Assemble a dial indicator and magnetic base so that the indicator stem rests on the face of the drive gear just inboard of the drive gear teeth. See Figure
Measuring Air Compressor Drive Gear TIR
Zero the dial indicator.
Rotate the drive gear two full revolutions. As the gear is rotated, the dial indicator may register both to the left and right of zero. The total amount the indicator needle moves to the left and right of zero, added together, gives the total indicated runout (TIR). Maximum allowable TIR is 0.08 mm (0.003 in.).
Installation of Air Compressor Drive Assembly
Install the air compressor drive assembly as follows:
Install the air compressor drive assembly to its original position in the gear case, using a new gasket between the housing and gear case.
Install the bolts and nut that secure the air compressor drive assembly to the gear case.
Using the required torque pattern, torque the five bolts and nut to 58-73 Nm (43-54 lbft). See Figure
The shorter bolt is installed in the two o'clock position.
Install the access cover. Use a new gasket between the access cover and the gear case cover, and torque the 5 bolts to 30-38 Nm (22-28 lbft) in a star-shaped tightening pattern.
If the engine is equipped with a power steering pump, install the proper steering drive coupling and power steering pump and cover assembly to the gear case cover. Install a new gasket between the cover and the gear case cover, and torque the 5 bolts to 30-38 Nm (22-28 lbft) in a star-shaped tightening pattern.
Connect the oil supply line at the "T" fitting, if applicable, at the top of the air compressor drive housing.
For engines used in coach applications, a high strength air compressor supply hose must be installed between the intake manifold and the air compressor inlet. This hose can be identified by the light blue color on the inside of the hose. Flat band spring type hose clamps must be used.
To avoid injury from flying parts when working with components under spring tension, wear adequate eye protection (face shield or safety goggles).
Install any other components that were removed for this procedure.