Top dead center (TDC) for piston #1 — location (Renault Clio 1)

1. TDC is the highest point in the cylinder that the piston reaches during a crankshaft revolution. Each piston reaches TDC at the end of the compression stroke, as well as at the end of the exhaust stroke. However, to adjust the ignition timing, the TDC at the end of the compression stroke is taken into account. On all engines described in this manual, cylinder #1 is located at the transmission end of the engine (from the flywheel side).

2. Apply the handbrake, then jack up the front right side of the car and place it on axle stands. Remove the right wheel.

3. Remove the plastic cover from inside the right wheel arch to gain access to the crankshaft pulley bolt.

4. Remove the spark plugs as described in Section 1.

5. Place your finger over the #1 spark plug hole in the cylinder head (closest to the flywheel). Turn the crankshaft clockwise until you feel pressure in cylinder #1. This indicates that the piston is rising in the cylinder.

6. Remove the plug from the hole at the top of the lower engine mount bracket/upper drive belt cover. While looking through the hole, continue to rotate the crankshaft until the TDC timing mark on the camshaft sprocket aligns with the mark on the top of the cover/bracket. If the lower cover/upper hanger has been removed, the mark on the camshaft sprocket should be aligned with the mark on the top of the valve cover (see illustrations).





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Note: There are five marks on the camshaft sprocket. But only the triangular mark on one of the teeth represents TDC. The other semicircular marks are used to adjust the valve clearances. When the lower engine mount/upper drive belt cover is installed, it is very difficult to align the marks correctly. If the timing mark on the crankshaft sprocket is aligned with the mark on the oil pump flange (see point 7), and the mark on the camshaft sprocket is visible through the hole in the engine mount bracket/timing belt cover, the piston is considered to be set to the TDC position.

7. If you now remove the crankshaft pulley (see Chapter 5), the timing mark on the crankshaft sprocket must be aligned with the TDC mark on the bottom of the oil pump flange (see illustration).