Valve clearances (Escort 5)

Setting the valve clearances correctly is very important because they largely determine the performance of the engine. If the valve clearances are too large, the engine will be noisy and the engine efficiency will be reduced because the valves open too late and close too early. A more serious problem occurs if the valve clearances are too small because the valves cannot close completely when the engine is hot, which can lead to serious engine damage.

These engines have hydraulic tappets which are automatically controlled by the oil pressure to compensate for the clearance between the camshaft lobe and the corresponding valve stem. Therefore, regular checking and adjustment of the valve clearances is not required. However, it is essential that good quality engine oil of the recommended viscosity is used and that the engine oil is changed at the recommended intervals. When starting a cold engine, there is a slight delay until the engine oil pressure equalizes throughout the engine, especially in the hydraulic tappets. Therefore, the valves may "knock" for about 10 seconds, after which the knocking disappears. This is a normal state of affairs, provided that all tappets operate silently thereafter.

After the engine has not been started for several days, the valves may "knock" for a longer period of time, as almost all the oil drains from the top of the engine and the bearing surfaces. During this time, care must be taken not to damage the engine, i.e., avoid sudden changes in engine speed until all the tappets are filled with engine oil. When warming up the engine, fast idle speed (maximum 2000 to 2500 rpm) should not be exceeded for 10 to 15 minutes, or until the valves stop knocking.

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