1984/10/08 Caterpillar

Information For Reversing Crankshaft Rotation Of All 6.25" Bore V8, V12 And V16 Engines{1000}

Usage:

D379, G379, D398, G398, D399, G399 Engines

Sometimes it is desirable to change the directional rotation of an engine. To do this, there are basic changes that must be followed when changing an engine from SAE Standard Rotation (see Illustration 1) to SAE Opposite Rotation (see Illustration 2). The changes and reason for the changes are as follows.

Illustration 1. SAE Standard Rotation Engine (CCW) V8 engine shown.

Illustration 2. SAE Opposite Rotation Engine (CW) V8 engine shown.

Crankshaft

The crankshaft (1) of V12 and V16 engines must be turned end for end so the oil hole for the connecting rod bearing will be in the correct position with respect to the load zone in the bearing. The crankshaft (1) of V8 engines have two oil holes for the rod bearing and do not need to be turned end for end. See Illustration 3.

Illustration 3. Crankshaft flange markings.

Accessory Drive Group

On engines with opposite rotation the oil pump (7) must still turn in the same direction as on engines with standard rotation. To do this, the front accessory drive must have the left and right hand idler gears (3, 4 and 5) exchanged. This means that mounting plates (2) for the gears must be reversed. New internal and external oil lines must be installed. See the Parts Book.

If the engine is not equipped with auxiliary drive groups on the left side of the engine, it will be necessary to purchase two new idler gears (4 and 5), shafts, and hardware to drive oil pump (7), and water pump (6). See the Parts Book for the gears and hardware needed for opposite rotation.

New internal and external oil lines must be installed. See the Parts Book.

New gears are required for the oil pump (7), water pump (6), and auxiliary drive groups (8 and 9). This is done so that the gears will have the correct helix angle (right or left hand) to mesh with the repositioned idler gears.

Crankshaft Seals

Crankshaft seals must be replaced on all engines except V8 engines with piston ring type seals. The V12 and V16 engines with piston ring type seals must have the seal throwers removed and installed on the opposite ends of the crankshaft. Since the throwers are pressed on the crankshaft, new throwers, seals and baffles should be used. The latest lip-type seals for the V8, V12 and V16 engines are designed to seal in only one direction of rotation. This means that the lip-type crankshaft seals must be replaced when engine rotation is changed. See the Special Instruction SMHS8301, for seal installation instructions.

Front Balancer Gear (V8 Engine Only)

On V8 engines, front balancer gear (10) must be replaced so that it is correctly timed to the crankshaft with the new idler gear arrangement.

Flywheel Ring Gear

The flywheel ring gear must be changed in order to have the correct helix angle for the engine with opposite rotation. The starting system must be changed so the engine is turned in the correct direction. See the Parts Book.

Fuel Injection Pump And Governor Drive Gears

Two gears drive the mechanical or electrical overspeed and safety shutoffs in the fuel pump and governor drive group. These gears must be changed so that the shutoffs continue to turn in the same direction when the rotation of the fuel pump drive shaft is changed. See the Parts Book.

Engine Camshaft

The engine camshaft must be turned end for end. The gear must be installed on the end marked "F". See the Parts Book and Service Manual.

Fuel Pump Camshaft

The fuel pump camshaft in the fuel pump housing must be turned end for end so the end of the camshaft marked "F" is nearest the mounting face for the thrust bearing. The pump assembly has to be disassembled for this change. After the change has been made, set the lifters on a test bench. See the Service Manual.

Mechanical Governor

For standard engine rotation, the location of valve (12) is on the right side of the governor drive housing. For opposite engine rotation, exchange plug assembly (11) with valve (12). See Illustration 4.

Magneto (Spark Ignited Engines)

On engines that are spark ignited, the magneto must be wired for correct firing order.

Starting Systems

Many configurations of air and electrical starting systems are used. Select a comparable starting group for opposite rotation. See the Parts Book for the serial number that applies.