Top Dead Center TDC) for number one piston — locating
Note: These engines are not equipped with a distributor. Piston position must be determined by feeling for compression at the number one spark plug hole, then aligning the ignition timing marks as described in Step 5.
Note: Positioning the piston(s) at TDC is an essential part of certain repair procedures discussed in this manual.
1. Top Dead Center (TDC) is the highest point in the cylinder that each piston reaches as it travels up-and-down during crankshaft rotation. Each piston reaches TDC on the compression stroke and again on the exhaust stroke, but TDC generally refers to piston position on the compression stroke.
2. Before beginning this procedure, be sure to place the transmission in Neutral and apply the parking brake or block the rear wheels. Remove the spark plugs (see Tune-up and routine maintenance). Install a compression gauge in the spark plug hole for cylinder no. 1.
3. Disconnect the cable from the negative terminal of the battery (see Engine electrical systems).
4. In order to bring any piston to TDC, the crankshaft must be turned to line up the TDC mark. When looking at the front (timing belt or timing chain end) of the engine, normal crankshaft rotation is clockwise.
5. Turn the crankshaft with a socket and ratchet or breaker bar until compression registers on the gauge, then turn it slowly until the TDC notch is aligned with the pointer on the timing belt cover (see illustration). The number one piston is now at TDC on the compression stroke.
i.5 Align the white (TDC) mark on the crankshaft pulley with the pointer on the timing chain cover
Note: There are two marks on the pulley. The white mark is for TDC, the red mark is only for checking ignition timing with a timing light.
6. After the number one piston has been positioned at TDC on the compression stroke, TDC for any of the remaining pistons can be located by turning the crankshaft in its normal direction of rotation, in 180-degree (1/2-turn) increments, and following the firing order. Divide the crankshaft pulley into two equal sections with chalk marks at each point, each indicating 180-degrees of crankshaft rotation. Rotating the engine past TDC no. 1 to the next mark will place the engine at TDC for cylinder no. 3.