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 mark on the crankshaft pulley/vibration damper with the edge of the crankshaft angle sensor mounting bracket

Aligning the pin (1) on the camshaft flange with the rib (2) on the camshaft bearing cap

Location of marks on the camshaft for setting the piston of the first cylinder to the top dead center

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 the mark on the crankshaft pulley/vibration damper with the edge of the crankshaft angle sensor mounting bracket, Alignment of the pin on the camshaft flange with the rib on the camshaft bearing cap, Location of marks on the camshaft for setting the piston of the first cylinder to top dead center):

• a - the mark on the crankshaft pulley / vibration damper must be aligned with the edge of the crankshaft angle sensor mounting bracket.
• b - the pin on the flange of the front part of the camshaft must be aligned with the rib on the camshaft bearing cover.
• c - the ignition distributor rotor must be aligned with the contact of the high-voltage wire of the first cylinder.