Caterpillar Caterpillar Backhoe Loader 420D 420D

NOTICE: Keep all parts clean from contaminants. Contaminants may cause rapid wear and shortened component life.

Use Tooling (A) to ensure that the No. 1 cylinder is at the top center compression stroke.

NOTICE: The valve timing and the fuel injection pump timing will be lost if the crankshaft is rotated when the idler gear is removed.

Position idler gear hub (9) and install bolts (7) in order to locate the idler gear hub.

Use a suitable press and Tooling (E) to install bushings (8) on each side of idler gear (5).

Remove bolts (7) from the idler gear hub. Install idler gear (5) on idler gear hub (9).

Install retainer plate (6) and bolts (7).

Check the end play for the idler gear.

Check the backlash between the idler gear and the camshaft gear.

a. Remove the crankshaft pulley. Refer to Disassembly and Assembly, 'Crankshaft Pulley - Remove and Install'.

b. Remove the front cover. Refer to Disassembly and Assembly, 'Front Cover - Remove and Install'.

NOTICE: Keep all parts clean from contaminants. Contaminants may cause rapid wear and shortened component life.

NOTICE: Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.

Refer to Special Publication, NENG2500, 'Dealer Service Tool Catalog' for tools and supplies suitable to collect and contain fluids on Cat products.

Dispose of all fluids according to local regulations and mandates.

1. Use Tooling (A) to ensure that the No. 1 cylinder is at the top center compression stroke. Refer to Testing and Adjusting, 'Finding Top Center Position for No. 1 Piston'.

Note: Install Tooling (B) through the camshaft gear. Install Tooling (C) into the crankshaft web.

NOTICE: Keep all parts clean from contaminants. Contaminants may cause rapid wear and shortened component life.

Remove the front cover (7). Refer to this Disassembly and Assembly Manual, 'Front Cover - Remove and Install'.

Remove the Allen head screws (2) and (9). Remove the accessory drive assembly (8) from the rear face of the front housing (11).

Remove circlip (6) from housing (8).

Use the Tooling (A) in order to remove the bearings (3) and (4) from the gear and the housing.

Remove the O-ring (12) from the front housing (8) and discard the O-ring.

Sign off on the accessory drive removal

Keep all parts clean from contaminants.

Contaminants may cause rapid wear and shortened component life.

1. Clean all mating surfaces thoroughly.

2. Ensure that thrust washer (10) is aligned with hollow dowel (12). Install the thrust washer on camshaft (11).

3. Install a new O-ring seal on the fuel injection pump housing.

4. Install Tooling (A) in the cylinder block in Hole (Y).

5. Position gasket (8) on Tooling (A). Install gasket (6) on the back side of front housing (5).

6. Position front housing (5) on the cylinder block. Install bolts (7) and bolts (9). Remove Tooling (A) and install the remaining bolts in order to secure the front housing to the cylinder block. Tighten bolts (7) and bolts (9) finger tight at this time.

NOTICE: Keep all parts clean from contaminants. Contaminants may cause rapid wear and shortened component life.

Inspect the condition of the teeth and the splines of the gear (5), the bearings (3 and 4), the circlip (6), and the groove for the circlip in the front housing (8) for wear and for damage. Replace any worn component or any damaged component.

Apply a small continuous bead of the Tooling (B) to the outer surface of the bearing (4). Support the front face of the housing (8). Position the bearing in the housing. Use a suitable adapter on the outer race of the bearing and press the bearing into the housing (8) until the bearing is against the front face of the recess. Remove any excess bearing mount compound.

Apply a small continuous bead of the Tooling (B) to the inner surface of the bearing (4). Support the bearing (4). Position the small hub of the gear (5) toward the bearing and press the gear (5) into the bearing until the shoulder of the gear is against the bearing. Remove any excess bearing mount compound.

Apply a small continuous bead of the Tooling (B) to the inner surface and the outer surface of the bearing (3). Support the bearing (4). Use a suitable adapter on the outer race of the bearing (3) and press the bearing into the housing and onto the shoulder of the gear. Remove any excess bearing mount compound.

Install the circlip (6) into the groove in the front housing (8). Install a new O-ring seal (12) on housing (8).

Lubricate the O-ring seal with red rubber grease and install the housing in front housing (11). Install Allen head screws (2) and (9) to secure housing (8) in the front housing.

Check the backlash between the idler gear and gear (5). The backlash for the gears is 0.11 to 0.17 mm (0.004 to 0.007 inch).

Install the front cover (7) on the front housing. Refer to this Disassembly and Assembly Manual, 'Front Cover - Remove and Install'.