If the cam -184- of the camshaft -185- points upwards, the poppet valve -203- is unloaded.
The spring -d- of the pusher unclenches the compensator -204- so that it rests on the bottom of the valve stem -195-, and presses the stem -a- against the plate -203- at the top. In this position, engine oil cannot penetrate into the space -c- and cannot flow out of it. As soon as the camshaft cam presses against the plate during rotation, the valve -b- closes and the oil inside acts as a solid body, because. the eye is practically not compressed. The length -L- changes during the operation of the mechanism, compensating for the wear of parts.
External signs of a hydraulic pusher are the presence of oil grooves and the absence of shims. Hydraulic pushers are not repairable.
Attention: Noise in the operation of the timing mechanism when starting the engine is normal. When the engine is not running, depending on the position of the cam, some oil is squeezed out of the pushrod. This results in a noise when starting the engine, which continues until then. until the hydraulic pushers are filled with oil again. Depending on the circumstances, this may continue until the engine reaches its operating temperature. To ensure reliable operation of the hydraulic pushers, there is a baffle in the cylinder head that prevents the oil from draining completely when the engine is not running.
Examination
Hydraulic pushers should be checked if, when the engine reaches its operating temperature, the noise in the operation of the vibration pusher mechanism does not stop.
Start and warm up the engine. After that stop it from idling until the fan stays on.
Raise the speed to 2500 rpm for 2 minutes.
If the noise in the tappets does not stop, then stop the engine and remove the cylinder head cover.
Rotate the camshaft until the cam nose of the tappet to be checked is in the upper position. Set the gearbox to idle. Engage handbrake. Turn the crankshaft at the central bolt in a clockwise direction.
Press the pusher down with a wooden or plastic wedge. If at the same time the pusher moves more than 061 mm before the valve starts to move, replace the hydraulic pusher
Attention: After installing a new hydraulic pusher, the engine must not be started for 30 minutes. Otherwise, the valve may collide with the piston, which may damage them.
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