Usually, we begin to check and replace the hydraulic pushers when there is an increased noise from the engine.

This is usually a ringing sound at the top of the engine.

Malfunctions of hydraulic pushers and methods of their correction are in the table at the end of the article.

The hydraulic pushers of the VAZ-2112 engine, made in the form of cylindrical pushers located between the camshaft and the valves, combine two functions: transferring force from the camshaft to the valves and eliminating gaps in their drive.

The operation of the hydraulic pusher is based on the principle of incompressibility of engine oil, which constantly fills the inner cavity of the hydraulic pusher during engine operation and moves its plunger when a gap appears in the valve drive.

This ensures that the tappet is in constant contact with the camshaft cam without play.

This eliminates the need for valve adjustments during maintenance.

Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112

The principle of operation of the hydraulic pusher is shown in Figure 1. Oil under pressure required for the operation of the hydraulic pusher is supplied to the internal cavities A and B from the channel

Into the engine lubrication system through the side hole in the pusher 6, made in the annular groove of its cylindrical surface.

When the valve 1 is closed, the pusher 6 (through the plunger 7) and the sleeve 9 are pressed against the cam 5 of the camshaft and the end of the valve stem by the expanding force of the springs 8, respectively.

The pressure in cavities A and B is the same, the check valve 3 of the hydraulic pusher is pressed against the seat in the plunger 7 by the spring 2 - there are no gaps in the valve mechanism.

When the camshaft rotates, the cam 5 runs onto the pusher 6, moving it and the plunger 7 associated with it.

The movement of the plunger 7 in the sleeve 9 leads to a sharp increase in pressure in the cavity B.

Despite small oil leaks through the gap between the plunger and the sleeve, pusher 6 and sleeve 9 move in one piece and open valve 1.

With further rotation of the camshaft, cam 5 reduces the pressure on the pusher 6 and the oil pressure in cavity B becomes lower than in cavity A.

The check valve 3 opens and passes oil from cavity A, connected to the engine oil line, into cavity B.

The pressure in the cavity B increases, the sleeve 9 and the plunger 7, moving relative to each other, choose a clearance in the valve mechanism.

The pressure of the oil supplied to the hydraulic pushers is controlled by a valve installed in the cylinder head.

Since after stopping the engine from the channels coming from the oil pump, oil flows into the oil sump, and the channels for supplying oil to the hydraulic pushers remain filled, after starting the engine, air locks may form in the cavities of the latter.

To eliminate them, calibration compensation holes are provided in the engine oil supply channels, which provide automatic purging of the hydraulic pusher cavities.

In addition, the compensation holes make it possible to somewhat reduce the pressure of the oil entering the hydraulic pushers at a high speed of rotation of the engine crankshaft, when the pressure in the cavity of the hydraulic pusher can become so great that its pusher, leaning on the back of the camshaft cam, will slightly open the valve at a moment that does not correspond valve timing.

Almost all hydraulic pusher malfunctions are diagnosed by the characteristic noise emitted by the gas distribution mechanism in various engine operating modes.

Valve noise can sometimes be eliminated by slightly turning the spring or valve around the longitudinal axis.

To do this, do the following.

1. Turn the crankshaft to a position where the noisy valve starts to open slightly.

2. Turn the spring a little - the valve turns at the same time.

3. Start the engine. If the noise persists, repeat steps 1 and 2.4.

If turning the spring and the valve does not give the desired result, check the condition of the spring and measure the clearances between the valve stems and guide bushings.

Eliminate increased (compared to nominal) clearances.

If the valve and the spring are in good order, and the knock of the valves is still heard when the engine is running, the hydraulic pusher is faulty. Replace it as follows.

We remove the receiver.

Cover the openings of the intake manifold with covers to prevent foreign objects from getting into it.

Remove the ignition module.

Remove the crankcase ventilation hose from the cylinder head cover branch pipe.

Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112

Using a 10 key, unscrew the bolt securing the bracket for the injector wiring harness connector.

With a head of 8, unscrew the 15 bolts securing the cylinder head cover (valve cover).

Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112

Remove the cylinder head cover.

We check the hydraulic pusher by pressing on it with a soft metal drift or a screwdriver (while the camshaft cam should be facing the pusher with its "back of the head").

In normal condition, the hydraulic pusher should be pressed with considerable effort. If the force is small, the hydraulic pusher must be replaced.

To do this, remove the toothed camshaft pulleys, (see information on removing the pulleys Removal and installation of the cylinder head of the VAZ-2112 engine).

Remove the wire from the oil pressure warning lamp sensor.

Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112

With a head of 8, we unscrew the 20 bolts securing the camshaft bearing housing

With a 15-inch head, unscrew the three nuts securing the rear support bracket.

Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112

Remove the rear support bracket

Remove the camshaft bearing housing

We take out the guide pipes of the spark plugs from the body.

Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112

To distinguish the intake camshaft from the exhaust camshaft, a belt is made on the intake shaft near the first journal.

We take out the camshafts with oil seals.

Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112

Remove the two rear cylinder head plugs and camshaft bearing housings

Attaching the magnet to the end of the hydraulic pusher, remove it from the cylinder head socket

If necessary, replace the hydraulic pusher with a new one and install it in the socket.

Before assembly, we clean the cylinder head and the camshaft bearing housing from the remnants of old sealant and oil.

Lubricate the bearing journals and camshaft cams with engine oil and place the shafts in the cylinder head supports.

Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112

On the surface of the shaft bearing housing, mating with the cylinder head, we apply Loctite sealant No. 574 with a flagellum about 2 mm thick.

Places of applying sealant to the bearing housing

Install the bearing housing and tighten the mounting bolts evenly.

Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112

After lubricating the O-rings of the guide pipes with engine oil, we install the pipes in the holes of the cylinder head and bearing housing.

Pressing in new camshaft oil seals.

On the other side of the cylinder head, press in the plugs.

We carry out further assembly in the reverse order of disassembly.

Before installing the cylinder head cover, apply Loctite No. 574 sealant to its surface, which is mated with the bearing housing.

Как заменить гидрокомпенсаторы клапанов двигателя ВАЗ-2112

Places of applying sealant to the cylinder head cover

After replacing the hydraulic pushers, the engine may operate with increased noise for a short time.

Possible malfunctions of hydraulic pushers, their causes and remedies

- Cause of malfunction

Remedy

Increased noise immediately after starting the engine:

Leakage of oil from a part of hydraulic pushers during long-term parking.

Noise that disappears a few seconds after starting the engine is not a sign of a malfunction, since some of the hydraulic pushers, which were under the load of the valve springs of the open valves (the oil supply channels remained open), leaked oil, the lack of which is replenished at the start of the engine operation

Intermittent noise in idle mode, disappearing with increasing engine speed:

- Damage or wear of the ball of the non-return valve

Replace the hydraulic pusher

- Contamination of the hydraulic pusher mechanism with wear products due to untimely oil change or its poor quality

Clean the parts of the mechanism from dirt. Use the oil recommended in the instruction manual

Increased noise in the idling mode of a warm engine, which disappears at an increased crankshaft speed and is completely absent on a cold engine:

- Oil flow through the gaps between the plunger and the hydraulic pusher liner increased due to wear

Replace the worn out hydraulic pusher assembly

Increased noise that occurs at a high crankshaft speed and disappears at a low frequency:

- Foaming with an excess of oil (above the upper mark on the dipstick) in the oil sump due to agitation by the crankshaft. The ingress of an air-foam oil mixture into the hydraulic pushers disrupts their operation

Bring up the oil level in the oil sump to normal

- Air intake by the oil pump when the oil level in the oil sump is too low

Bring up the oil level in the oil sump to normal

- Damage to the oil receiver due to deformation of the oil sump when hitting a road obstacle

Repair or replace defective parts

Continuous noise from one or more valves, independent of the crankshaft speed:

- The emergence of a gap between the tappet and the cam of the camshaft due to damage or contamination of parts of the hydraulic pusher

Remove the cylinder head cover, alternately install the camshaft cams with the protrusions up and check for a gap between the tappets and the cams.

When sinking (for example, a wooden wedge) the tested hydraulic pusher, compare the speed of its movement with the rest. If there is a gap or increased travel speed, disassemble the hydraulic pusher and clean its parts from dirt or replace the hydraulic pusher

* The following reasons for the increased noise in idle mode are possible, which increases with an increase in the crankshaft rotation speed up to 1500 rpm and is not associated with the operation of hydraulic pushers:

- increased clearances between valve stems and guide bushings;

- increased to a value exceeding the permissible value, misalignment of the valve and seat;

- non-parallelism of the ends of the valve springs;

- greater than permissible runout of the valve head chamfer.