2.2.2. Check of gaps in the mechanism of the drive of valves on engines M 102.980 and M 102.982

Principle of hydraulic compensation of a gap of valves

On engines M 102.980 and M 102.982 valvate yokes have hydraulic pushers.

Hydraulic pusher of valves

1 — the accumulative camera
2 — the working camera
3 — a pusher
4 — a yoke

5 — a returnable spring of the ball valve
6 — a plate of a pusher
7 — a persistent washer of a pusher

In accumulative 1 and the worker 2 cameras come to operating time of the engine oil under low pressure (no more than 3 kg/cm 2). Thereby the continuous contact of a pusher 3 with a valve core is provided. When raising a yoke the 4th cam the pusher enters in a yoke, the ball valve is closed that causes increase in pressure in the working camera. Owing to incompressibility of oil transfer to a pusher and the valve of the movement from a cam and a yoke is provided. The spring 5 provides the constant pressure of a pusher upon valves and at the stopped engine.


If there are doubts in malfunction of pushers (knock, deterioration in operation of the engine), check their state.


  1. Uncover a head of cylinders.
  2. Turn a bent shaft of the engine manually so that the nape of a yoke was turned to a camshaft cam.
  3. Measure the pusher course against the stop in a yoke. If the course exceeds 0,5 — 2,4 mm, change thickness of a spherical plate 6 or a persistent washer of the 7th pusher.
  4. If one of pushers falls quicker, than others, then it should be removed and replaced.