BELT GP-SERPENTINE 3246890 - Caterpillar

3100 Series Engines;
3406 EnginesThe 1P5550 Fuel Cam Locking Tool Assembly is used to prevent rotation of the fuel pump camshaft on the above engines while the pump drive bolt or bolts are tightened. According to several reports, the brass tip on the tool has rapidly become worn or damaged in use and will not hold the cam in position.
The primary cause of these problems is the use of the tool when flow timing the engine on Number 1 Cylinder. When the engine timing is adjusted on Number 1 Cylinder, the timing slot in the fuel pump camshaft is either exactly or nearly in alignment with the hole in the housing where the tool is installed. If the slot is in exact alignment, the brass tip on the tool will fit into the slot and be broken or damaged when the drive bolts are tightened. If the slot is nearly in alignment, the brass tip on the tool will be in contact with the sharp edge of the slot when the tool is tightened. The sharp edge will damage the tip, and the damage will be increased when the drive bolts are tightened.
This tool damage can be prevented by timing the engine on a cylinder other than Number 1 Cylinder. The best cylinders to use are the Number 6 Cylinder for 3406 Engines, and the Number 4 Cylinder on 1100 and 3100 Series Engines. When this is done, the camshaft slot will be in a different position and the tool will be in contact with a smooth, even surface. This will prevent damage to the brass tip, and will extend the service life of the tool.