Valve clearance (Renault 19)

The individual parts of the valve train, and especially the valve stems, stretch and lengthen as the engine heats up. Therefore, a small gap between the camshaft and the valve tappet is necessary for the valves to function properly (F-engine) and, accordingly, between the camshaft and the rocker arm (C-engine). To help you understand the enormous importance of this type of engine adjustment, we will provide a list of malfunctions that may occur when the valve clearance is set incorrectly:

— too small gap leads to the valves not fitting tightly to the seats, and this primarily concerns the exhaust valves, which heat up very much. At the same time, they cannot give off their heat to the seat rings. The edges of the valve heads are deformed, destroyed, and the valve seats burn out. Compression decreases, the engine loses power, starts worse, and consumes more fuel.

— too big gap in the valve train results in the valves opening later than necessary, the cylinders not being filled with the mixture completely and the engine not operating at full power. The valve train, especially in C-engines, is louder and wears out somewhat faster.

[The text is available on this website renaultbook.ru]