C27 and C32 Engines Finding Top Center Position for No. 1 Piston Caterpillar

The No. 1 piston at Top Center (TC) on the compression stroke is the starting point of all timing procedures.

Note: Some engines have two threaded holes in the flywheel. These holes are in alignment with the holes with plugs in the left and right front of the flywheel housing. The two holes in the flywheel are at a different distance from the center of the flywheel. Therefore, the timing bolt cannot be put in the wrong hole.

Illustration 1	g01123281
Locating Top Center on the left side of engine (1) Timing bolt (2) Timing bolt location (3) Cover

Illustration 2	g01123294
Locating Top Center on the right side of engine (1) Timing bolt (2) Timing bolt location (3) Cover

1. Timing bolt (1) is a cover bolt. The timing bolt can be installed in either the left side of the engine at location (2) or in the right side of the engine at timing bolt location (2). Remove both bolts (1) and cover (3) from the flywheel housing. Remove the plug from the timing hole in the flywheel housing.

2. Put timing bolt (1) (long bolt that holds the cover on the flywheel housing) through the timing hole in the flywheel housing. The 9S-9082 Engine Turning Tool and a 1/2 inch drive ratchet wrench are used in order to turn the engine flywheel in the direction of normal engine rotation. Normal engine rotation is counterclockwise. Normal engine rotation is viewed from the flywheel end of the engine. Turn the engine flywheel until the timing bolt engages with the threaded hole in the flywheel.
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   Illustration 3	g01123312
   Using 9S-9082 Engine Turning Tool (1) Timing bolt (4) 9S-9082 Engine Turning Tool

   Note: If the flywheel is turned beyond the point of engagement, the flywheel must be turned in the opposite direction of normal engine rotation approximately 45 degrees. Then turn the flywheel in the direction of normal rotation until the timing bolt engages with the threaded hole. The procedure will eliminate the backlash that will occur when the No. 1 piston is put on the top center.

3. Remove the front valve mechanism cover from the engine.

4. The inlet and exhaust valves for the No. 1 cylinder are fully closed if the No. 1 piston is on the compression stroke and the rocker arms can be moved by hand. The No. 1 piston is on the exhaust stroke, if the rocker arms cannot be moved and the valves are slightly open .

Note: After the actual stroke position is identified, and the other stroke position is needed, remove the timing bolt from the flywheel. The flywheel is turned 360 degrees in a counterclockwise direction. The timing bolt is reinstalled.