2.8. Hydraulic dish-shaped pushers

All VW T4 engines are equipped with hydraulic dish-shaped pushers which reduce noise in the drive of valves and, besides, do not demand within service of adjustment of valvate gaps.

Work of a dish-shaped pusher

During the operation of the engine the dish-shaped pusher 203 unloads if the cam 184 cam-shafts 185 is located above. In this case the spring (d) unclenches the compensator 204 so that it below rests against a valve 195 core, and at the top of press the finger (a) presses a dish-shaped pusher 203 to a cam-shaft.

In this situation all openings (e) are blocked and engine oil cannot neither flow, nor follow from the working camera (c). As soon as the dish-shaped pusher is loaded with a cam of the rotating cam-shaft, the ball valve (v) will be closed and the oil which is in the working camera, because of the incompressibility will work as one solid body. Thus, the distance (L) at each turn of a cam-shaft will adapt respectively to the changing sizes of the interfaced details.

External sign of a hydraulic dish-shaped pusher is the running all over oil flute and lack of adjusting washers.


Noise in the drive of valves at start of the engine are normal. At the stopped engine, depending on the provision of a cam, from a pusher the bigger or smaller amount of oil is squeezed out. It leads to emergence of the noise which are not stopping until a hydropusher, at the working engine will not be filled with oil again. Depending on circumstances this process can continue until the engine does not get warm up to the working temperature.

For ensuring perfect work of hydropushers, in a head of the block of cylinders there is an oil leak blocking interfering a full effluence of oil from a head of the block of cylinders at the stopped engine.


Hydraulic pushers need to be checked if at achievement by the engine of working temperature noise do not vanish in the drive of valves.

1. To warm up the engine in the movement, to leave to idle, the radiator fan will not turn on yet.
2. Within 2 minutes to lift engine turns to 2500 rpm.
3. If hydropushers continue to publish loud noise, to kill the engine and to uncover a head of the block of cylinders. To turn a cam-shaft until cams of the checked cylinder are not directed up. For this purpose to install the transmission in neutral situation, to tighten the emergency brake and to turn the crankshaft for a bolt of fastening of a belt pulley a suitable key clockwise.


Not to rotate for a bolt of fastening of a driving gear wheel of a cam-shaft since it will lead to an overload of a gear belt. Cranked and cam-shafts can be turned and as follows: to include the 5th transfer and to push the car forward or back.

4. To press a dish-shaped pusher down a wooden or plastic wedge. If the side play more than 0,1 mm, a dish-shaped pusher is felt at the same time to replace.


After installation of a new hydropusher, within about 30 min. the engine cannot be started, otherwise the valve will collide the piston that can lead to their breakage.