3.16. Check of hydraulic pushers of valves
The correct installation of valvate gaps in many respects defines operation of the engine. If valvate gaps too big, noisiness increases and overall performance of the engine as valves open too late decreases and are closed too early. If valvate gaps too small, valves cannot be closed completely on the hot engine that can lead to its serious damage.
On engines establish hydraulic pushers which automatically under the influence of pressure in the lubrication system compensate a gap between a cam of the camshaft and the corresponding rod of the valve. Therefore regular check and adjustment of valvate gaps are not required. However it is necessary to use engine oil of high quality and the recommended viscosity and to replace it with the required frequency. At launch of the cold engine there is a small delay caused by alignment of pressure of engine oil in all parts of the engine, especially in hydraulic pushers. Valves can knock about 10 seconds then begin to work silently.
If the engine was not launched by several days, valves can knock during longer time as almost all oil flows down from the top part of the engine and the working surfaces of bearings. At this time it is necessary to be careful not to damage the engine: to avoid sharp change of power setting until all pushers are filled with engine oil. At warming up of the engine the idling rotation frequency (from at most 2000 to 2500 min.-1) should not increase within 2 minutes or yet the knock of valves will not stop. If noise of pushers does not stop, stop the engine and perform the following operations (temperature of the engine has to be not less than 80 °C).
Uncover a head of the block of cylinders.
Turn a bent shaft until the cam over the checked pusher is not established directly up.
Press a pusher a wooden or plastic wedge (fig. 3.1-91). If the free wheeling of a pusher is more than 0,2 mm, pushers need to be replaced.
Establish a cover of a head of the block of cylinders.
Wait about 30 minutes before launch of the engine. It is necessary in order that work of hydraulic pushers was stabilized, otherwise pistons will hit against valves.
Processing of saddles of valves
Saddles of valves with wear tracks or a podgoraniye need to be processed with obligatory preservation of corners and sizes of a facet.
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Fig. 3.1-92. Minimum admissible distance from a valve end face to the top surface of a head of the block of cylinders
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If the saddle of the valve needs to be processed, determine the maximum quantity of metal which can be removed. If the excessive amount of metal is removed, work of hydraulic pushers will be broken. Insert the valve into the directing plug and press it to a valve saddle. Measure distance from the end of a rod of the valve to the top surface of a head of the block of cylinders (fig. 3.1-92). Minimum admissible distance and makes 33,8 mm for inlet valves and 34,1 mm for final valves. At excessive wear of a saddle of the valve the head of the block of cylinders needs to be replaced.
After any processing of saddles it is necessary to grind in valves.