Top dead center (TDC) of the piston of the first cylinder (Mercedes-Benz E-Class W124)

The top dead center of a piston is the point through which each piston passes as the crankshaft rotates. Each piston reaches the TDC position at the end of the compression stroke, then again at the end of the exhaust stroke. The TDC of the piston of the first cylinder is used to set the engine timing mechanism.

Alignment of the TDC mark on the crankshaft pulley with the pointer

Alignment of the groove on the camshaft flange with the upper plane of the cylinder head

1. Mark the position of the high-voltage wire terminal of the first cylinder on the distributor cap.

2. Remove the cylinder head cover.

3. Using the crankshaft pulley mounting bolt, turn the engine crankshaft clockwise until the following marks are aligned with the pointers (see fig. Alignment of TDC mark on crankshaft pulley with pointer, Alignment of groove on camshaft flange with upper plane of cylinder head):



a – TDC mark on the crankshaft pulley with an indicator on the drive chain cover;

b – recess on the flange on the front part of the camshaft with the upper plane of the cylinder head;

c – ignition distributor rotor with a groove in the ignition distributor housing.

4. After all marks are aligned, the piston of the first cylinder is at the top dead center in the compression stroke.