GUARD AS 4920451 - Caterpillar

Removal Procedure (Latest Heavy-Duty Idler Gear)
Table 1
Required Tools
Tool Part Number Part Description Qty
A 230-6284 Timing Pin (Camshaft) 1
B 230-6283 Timing Pin (Crankshaft) 1
C - Bolt
M8x80mm 1 Start By:
If the engine is equipped with an air compressor, remove the air compressor. Refer to Disassembly and Assembly, "Air Compressor - Remove and Install".
If the engine is equipped with a vacuum pump, remove the vacuum pump. Refer to Disassembly and Assembly, "Vacuum Pump - Remove and Install".
If the engine is equipped with an accessory drive, remove the accessory drive. Refer to Disassembly and Assembly, "Accessory Drive - Remove and Install".
Remove the fuel injection pump gear. Refer to Disassembly and Assembly, "Fuel Pump Gear - Remove".
Remove the valve mechanism cover. Refer to Disassembly and Assembly, "Valve Mechanism Cover - Remove and Install". Note: Care must be taken in order to ensure that the fuel injection pump timing is not lost during the removal of the fuel pump gear. Carefully follow the procedure in order to remove the fuel pump gear.
Keep all parts clean from contaminants.Contaminants may cause rapid wear and shortened component life.
Note: The assembly of heavy-duty idler gear is not serviceable. Do not disassemble the heavy-duty idler gear.
Ensure that number one piston is at the top center position on the compression stroke. Refer to the Systems Operation, Testing and Adjusting, "Finding Top Center Position for No. 1 Piston".
Illustration 1 g01473492
Alignment of timing marks
Ensure that Tooling (A) is installed into Hole (X) in camshaft gear (1). Use Tooling (A) in order to lock the camshaft in the correct Position. Note: Ensure that the gears are marked in order to show alignment.
Ensure that Tooling (B) is installed in Hole (Y) in the front housing. Use Tooling (B) in order to lock the crankshaft in the correct Position.
Illustration 2 g01473493
Typical example
Loosen nuts (4) on all rocker arms (5). Unscrew adjusters (3) on all rocker arms (5) until all valves are fully closed. Note: Failure to ensure that ALL adjusters are fully unscrewed can result in contact between the valves and pistons.
Illustration 3 g01473556
Typical example
Illustration 4 g01473559
Typical example
Remove bolts (7) from the assembly of heavy-duty idler gear (6).
Remove the assembly of idler gear (6) from the recess in the front housing. Note: The idler gear must be tilted during removal.
Illustration 5 g01473500
Typical example
If necessary, remove plate (7). Install Tooling (C) into threaded Hole (Z) in order to remove plate (7).