Top dead center (TDC) of piston No. 1 (Opel Omega B)

The top dead center is taken to be the highest point reached by piston N1 during the compression stroke.

Piston N1 is located in the front part of the right cylinder bank on the timing belt side.

1. Disconnect the negative battery cable and, if necessary, remove the spark plugs.

2. Remove the outer timing belt cover.

3. Turn the crankshaft so that the timing marks on the camshaft sprockets are facing upward and aligned with the slots in the timing belt cover (indicated by arrows). Perform this procedure as for the right cylinder head (drawing on the left), and for the left (drawing on the right). There are two marks on each sprocket. Below is a table showing the use of these marks.

4. Align the mark on the crankshaft pulley with the pointer (indicated by arrows) on the oil pump housing. When the marks are aligned, piston N1 is at TDC during the compression stroke.

Camshaft Sprockets	The label to use
exhaust valves of the right cylinder head	1
intake valves of the right cylinder head	2
intake valves of the left cylinder head	3
exhaust valves of the left cylinder head	4