Caterpillar 3056 GEN SET ENGINE 7AK — Set The Top Center Compression Position For No. 1 Piston (Alternate Method)
Adjustments · No. 1 piston top center (compression stroke)
For the Caterpillar 3056 GEN SET ENGINE 7AK, from the Caterpillar service manual.
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Before you start
- Be careful when you rotate the crankshaft. The No. 1 inlet valve will be held in position on top of the piston. If the crankshaft is not positioned properly, the valve may fall from the cylinder head.
Procedure
- Fasten a temporary pointer to the front of the front cover. Put the tip of the pointer close to the edge of the damper or the pulley.
- Remove the fuel injection nozzles and the valve mechanism cover.
- Rotate the crankshaft clockwise (facing the front of the engine) until the pushrod for the inlet valve of the rear cylinder begins to tighten.
- Rotate the crankshaft further by 1/8 of a turn clockwise. Insert a lever between the rocker lever and the valve spring cap of the No. 1 inlet valve. Open the inlet valve. Put a spacer approximately 5
- Slowly rotate the crankshaft counterclockwise until the piston makes contact with the open valve. Make a temporary mark on the damper or the pulley aligned with the tip of the pointer.
- Rotate the crankshaft clockwise by one or two degrees. Remove the spacer between the valve stem and the rocker lever. Rotate the crankshaft by 1/4 of a turn counterclockwise. Put a spacer approximatel
- Slowly rotate the crankshaft clockwise until the piston makes contact with the open valve. Make another temporary mark on the damper or the pulley aligned with the tip of the pointer.
- Make a temporary mark at the center point between the two marks on the damper or the pulley. Remove the other two marks. Rotate the crankshaft by 1/8 of a turn counterclockwise. Remove the spacer betw
- Slowly rotate the crankshaft clockwise until the center mark made in Step 8 aligns with the tip of the pointer. The No. 1 piston is now at top center on the compression stroke.
- Install the valve mechanism cover and the fuel injection nozzles.
- Remove the temporary pointer from the front of the front cover.
Tools required
- 150-3992 Timing Pin (Bosch) Amazon
- 150-3993 Timing Pin (Stanadyne and Delphi) Amazon
- Temporary Pointer Amazon
- 6V-3075 Dial Indicator Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Spacer approximately 5 mm (0.2 inch) thick between the valve stem and the rocker lever
Source: Caterpillar service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.