Repair of the cylinder head

Springs of valves and valve guides

To take full control of the valve spring, use a special tool to check the springs. If it is not, then set the spring in a row on a smooth surface so that knurling was closed at the bottom. Put next to a spring steel bracket and measure the gap between the top of the spring and the area. The gap must not be greater than 2.0 mm. Otherwise skewed spring.

Valve guides

Control beating the valve stem inside the guide sleeve is performed using the measuring device VW387, dial gauge (Fig. 38).

Rock the plate at the top of the valve back and forth and check the dial gauge readings. If it shows a value of greater than 1.0 mm on the intake valves, and more than 1.3 mm - at the outlet, the valve guide to be replaced. Also check the general condition of the cylinder head before replacing the valve guides. Cylinder head with abrasion between the valve seats or between the valve seat and threaded holes candles can be reground and used again, provided that the width of the crack does not exceed 0.5 mm. After regrinding of the cylinder head value a (see. Fig. 37) should be less than 139,50 mm. This - the minimum size. The nominal size of the height of the cylinder head is (140 ?� 0,1) mm. Measurements should be carried out either caliper or measuring ruler, placing the cylinder head on a flat surface;

- Put the cylinder head on the table to remove the bale valve guide;

- The removal of the valve guide is produced by the pressing off of the camshaft cylinder head (Fig. 39) with a punch.

Cylinder head may be heated in order to facilitate this work. On the punch you need to tie a pin that fits the size of the inside of the valve guide:

- When replacing the valve guide and change the valve itself. Then you need to resharpen the valve seats;

- The new valve guides before installing the engine oil and grease Press fit them on the part of the camshaft in the cold cylinder head so that the shoulder of the valve guide entered the cylinder head. Wherein the pressing pressure should not be more than 1 m, since otherwise the collar may be cut. The cylinder head must lie on a completely flat surface;

- After pressing, expand the opening in the guide sleeve intake and exhaust valves scan 7.0 mm;

- After replacing the valve guides must grind the valve seats;

- Wash thoroughly after grinding saddle and channels of the cylinder head and blow compressed air.

Valve seats

Check and repair the valve seats is carried out as follows:

- Check all valve seats for wear and scratches. On working facet saddles (area of contact with the valves) should be no pinholes, corrosion and damage. Minor damage can be eliminated by grinding the seats - 45 ?� cutter. Thus as little as possible remove the metal. Sand can be both manually and using grinder. If the seat is strongly worn, they must be milled again. The shape of facets of saddles of valves shown in

Fig. 40 and 41;

- Carry out the following measurements in order to keep the size of b, for this:

- Insert the valve in its guide sleeve and press on the valve seat;

- Measure the height of the protrusion end of the valve stem on the top edge of the cylinder head (Fig. 42). To do this, put on a plane cylinder head measuring range. Intake valve, it should be 33.9 mm, and the exhaust valves - 34.1 mm;

- Calculate the value of b, which requires the measured value subtracted the minimum distance.

This is necessary so as not to bore the valve seat in the cylinder head too. Valve seats should be milled and, if installed new guides. To do this:

- Lightly milled at 45 ?�, and then the cutter 30 ?� angled upper edge of the valve seat to reduce the width from the valve seat and bring it to a value of 1.7 mm - for the inlet and 2.0 mm - for the exhaust valves. Treatment should be discontinued as soon as the size of the valve seat made of these sizes. Saddles and exhaust valves have a diameter of the restrictors. During the treatment, take care not to damage these constraints;

- Sand the machined valve seats. To do this, apply a small amount of the valve seat lapping diamond paste and install valves in the saddle. Attach the suction cup onto the valve and turn the valve with the help of back and forth (Fig. 43);

- Check valve seat in place of the valve disc and sealing ring. Must be seen uninterrupted, matte ring on both parts;

- Apply a pencil a few dashes on the ring in the valve plate. Dashes have to be drawn around the ring with an interval of about 1 mm. Then carefully insert the valve into directing plug, lower it into the seat and turn in a circle of 90 ?�, applying light pressure to the valve;

- Remove the valve and check if you still have inflicted pencil lines with sealing ring;

- After grinding thoroughly clean all parts of the mud and lapping compound. If the valve seat width of these size ranges, the cylinder head can be installed. Otherwise, the valve seat must be treated again, or at the very least install a new cylinder head.

Valves

Remove carbon from valves. Check to see if the core and there are no cracks in the plate, for which:

- Perform measurements in accordance with Fig. 44 and replace any inappropriate This valve size. The values of a, b and c can be taken from the table of tolerances and control;

- If the end of the valve stem is worn, it can be ground on the grinding machine, with the proviso that will be removed during grinding of not more than 0.50 mm metal;

- Intake valve plates can be ground to the grinding machine for valves, with the proviso that the value b (Fig. 45) is not less than 0.5 mm.

Cylinder Head

Wash the cylinder head and clean the oil channels. Remove the carbon deposits from the combustion chamber and the exhaust ports from the surface with a wire brush. Carefully clean the contact surfaces of the cylinder head and cylinder block. Inspect the cylinder head. On the neck a support under the camshaft and in the holes under the tappets should be scuffing or damage. Cracks in any area of the cylinder head are not allowed.

Check the surface of the cylinder head on the deformation (Fig. 46).

To do this, put on the head of the measuring range with the help of the probe, check the clearance along, across and diagonally. If it is less than 0.10 mm, the cylinder head can be sanded. If the gap in any place longer, the cylinder head must be replaced, as the removal of more of the metal layer can adversely affect the engine compression.

Camshafts

Camshafts are not interchangeable, primarily because of the presence on one of the Hall sensor. Shafts vary in number for ordering spare parts.

When viewed from the camshaft, pay attention to the surface of the bearing journals (bearing location), the cams, which should be well polished and undamaged. If you find traces of seizing or profound risks, the camshaft must be replaced.

Before installing the camshaft must perform the following work:

- Establish a camshaft extreme tails on two prisms or between the jaws of the lathe and set the meter in place of the middle bearing (neck) of the camshaft (Fig. 47);

- Slowly rotate the camshaft and watch the meter readings. If the readings on the instrument runout exceeds 0.01 mm, the camshaft must be replaced because it is deformed. In a similar manner, check the second shaft;

- To measure the axial clearance of camshafts, insert them both into the cylinder head (without pushers), lock the extreme bearing and place the cylinder head on a flat surface. Set the gauge from the end of the cylinder head and the shaft rocking back and forth in the axial direction (Fig. 48, arrows). The axial clearance must not exceed 0.15 mm. Otherwise worn working surface of the bearing cap.