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6.1.1. Hydropushers

On engines of the E-class there is a hydraulic system of adjustment of valves. Use of system of hydraulic adjustment with hydropushers significantly reduces noise of the engine in comparison with operation of ordinary valves. Hydropushers are located directly between cams of the camshaft and an end face of a rod of the valve, they provide existence of a gap in valves, and at the same time the closed valves densely adjoin to a saddle. The principle of work of hydropushers is described in section 4.
Other malfunctions which are described below can be the knock reasons in the engine also.

Knock of valves at launch of the engine
At launch of the engine hydropushers enter work at once, special backpressure valves are for this purpose used. They are intended for filling by oil of the lubrication system and oil channel of hydropushers and bearings of the camshaft.
If the engine long time did not work, the knock of valves is not the reason of breakage. The matter is that at long not working engine oil from hydropushers flows down. When the engine is launched, hydropushers are filled with oil, and the knock vanishes.
If the knock of valves in the field of a head of cylinders continues on the heated-up engine, it testifies to defects of one or several hydropushers. They are not subject to repair, and they should be replaced.
The following can be the reason of the knock of valves continuing from several seconds to 10 min.:
– before launch of the engine in it oil was replaced;
– the engine did not work more than a day;
– the engine is launched after repair (replacement of pushers).

   Check of hydropushers
1. Warm up the engine up to the working temperature and leave to idle before turning on of the fan.
2. Within 2 min. let's work to the engine on the raised turns (2500 min.-1).
3. If the knock of valves continues — stop the engine.
4. Uncover a head of cylinders.
5. Turn a bent shaft of the engine so that at the checked cylinder cams of the camshaft were directed up.

Fig. 5.2. Check of hydropushers: 1 – pin; 2 – pusher

6. A wooden or plastic pin of 1 (fig. 5.2) press on a pusher 2.

Use of the metal tool as it leads to emergence of scratches is not allowed.

If you feel "air" until opening of the valve or a pusher quickly and without resistance falls, so the pusher demands replacement. Experts in auto repair shop have to do this work.

Excess of number of nominal turns and service life of the engine
The increased speed reduces engine service life. If the engine works at the raised turns and at the same time atypical knocks or noise are heard, it speaks about wear of a bent shaft or the valvate mechanism. If wear strong, then breakage of a pusher is possible, the valve and the cylinder will not work. You will feel it on deceleration of power of the engine. The worst option — destruction of valvate springs and hit of fragments on the moving piston. As a rule, it leads to serious breakage of the engine