Top dead center (TDC) of the piston of the first cylinder (Opel Vectra B)

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, and again at the end of the exhaust stroke. The TDC of the piston of the first cylinder in the compression stroke is used to set the engine timing mechanism. Cylinder N1 is on the toothed belt side. The engine crankshaft rotates clockwise when viewed from the right side of the car.

1. Remove the ground cable from the battery. To improve access to the crankshaft pulley, apply the handbrake, raise the front of the car and secure it on stands.

2. To check camshaft cam location, remove the cylinder head cover or remove the brake vacuum pump with the timing gear mounting hole visible on the camshaft.

3. Turn the engine with a wrench on the crankshaft pulley until the timing mark on the crankshaft pulley aligns with the pointer. In this case, the pistons of the first and fourth cylinders are at the top dead centers.





4. To determine which piston is in the compression stroke, check the position of the camshaft lobes. If the piston of the first cylinder is in the compression stroke, the camshaft lobes of the first cylinder (indicated by arrows in the photo on the left) will be directed upwards and the valve timing mechanism installation hole (indicated by the arrow in the photo on the right) on the left side of the camshaft will be in the upper position. If the cams of the first cylinder of the camshaft are pointing down, turn the engine crankshaft 360°.





5. Remove the crankshaft position sensor from the engine block.



6. To lock the crankshaft in the position where the piston of the first cylinder is at top dead center in the compression stroke, install the pin through the hole of the crankshaft sensor on the front of the cylinder block.

(The source is on the online website www.opelbook.ru)