MUFFLER AS 4W9073 - Caterpillar

The timing gears are located in a compartment at the rear of the cylinder block which uses the front face of the flywheel housing as a cover. The timing gears keep the rotation of the crankshaft, camshaft, balancers if so equipped, and the governor drive gear in the correct relationship to each other. A gear in front of the crankshaft rear flange drives the timing gears.
TIMING GEARS (8 Cylinder Engines Illustrated)
1. Governor drive gear. 2. Camshaft cluster gear. 3. Balancer gear. 4. Crankshaft gear.The crankshaft gear (4) drives the camshaft cluster gear (2) which in turn drives the balancer gear (3) and governor drive gear (1). The camshaft small cluster gear is held to the camshaft with key, plate and bolts. The 8 cylinder engines use balancers, therefore balancer gear (3) is used only on these engines.Camshaft
The camshaft rotates in bearings located in the V of the engine. It is driven by a gear on the rear of the crankshaft. The camshaft is positioned by a thrust washer secured to the face of the cylinder block. The cams which actuate the inlet and exhaust valves are forged as one piece with the camshaft.Camshaft Cluster Gear Removal
Position the engine with No.1 piston at top center on the compression stroke as follows:1. Remove the timing mark cover on the flywheel housing and turn the flywheel in the direction of engine rotation until No.1 piston is at TC (top center) on compression stroke as indicated by flywheel pointer (1) and the position of No.1 cylinder valves.
TIMING MARKS ON FLYWHEEL (16 Cylinder Engine Illustrated)
TIMING MARKS ON FLYWHEEL (12 and 8 Cylinder Engines Illustrated)
1. Pointer. If the flywheel is turned too far, turn it back about 60° and again rotate the flywheel in the direction of normal rotation until No.1 piston is at TC (top center) on compression stroke as indicated by the flywheel pointer. On earlier natural gas engines with magnetos on the engine see the topic, TIMING THE MAGNETO.2. Remove the flywheel housing. See the covering topic.
PREPARING TO REMOVE CAMSHAFT CLUSTER GEAR
1. Bolt and lock. 2. Small cluster gear. 3. Bolts (eight). 4. Retainer. 5. Large cluster gear.3. Remove the large cluster gear (5) as shown.
To avoid piston and valve interference, do not rotate the crankshaft with the large camshaft cluster gear removed and the camshaft installed.
LARGE CLUSTER GEAR REMOVAL
5. Large cluster gear.4. Remove the bolts and locks (1), which secure the thrust washer to the cylinder block, through the holes in the small cluster gear and remove the thrust washer.5. Remove the service meter drive adapter at front of the camshaft on later engines.6. Remove the small cluster gear by using 7F9540 Hydraulic Puller, 8F3672 Puller Plate, 8B7548 Push Puller with 8B7550 Legs, two 4B4280 Washers (1/2 in.) and two L1329 Bolts, 1/2"-13NC, 3 in. (76,2 mm) long.
TOOLS NEEDED FOR PULLING CAMSHAFT GEAR7. Inspect all parts for wear or damage and replace if necessary. See the SPECIFICATIONS, for the correct clearances and dimensions.Camshaft Cluster Gear Installation
1. Install the small cluster