Repair of the cylinder head

All parts of the cylinder head must be checked for wear. It should thoroughly clean the gasket surface of the cylinder head (sometimes remain fragments become attached sheet). Monitor the status of the cylinder head is carried out according to the instructions below.

Valve spring

For proper verification, the valve springs springs requires a special tester. If it is not at your disposal, you can conduct a simple comparison of the old and new valve springs. For this purpose, take the old and new valve springs and clamp them in a vice. Slowly gripping jaws, watch the degree of compression of both springs. If they contract the same, it indicates good condition of the old spring. But if you worked a greater degree of compression springs (shorter looks new), this is a clear sign of fatigue wear - this spring should be replaced. Valve springs replaced by a complete set.

Prepared for fitting a spring put on a flat and smooth surface (glass) so that the turns tightly closed at the bottom. On top of the spring is placed a metal area and checked the gap between the coil spring and upper corner of the plane. This gap should not exceed 2.0 mm. Otherwise, the springs should be replaced.

Valve guides

Valve guides, made of cast iron, have different diameters for the inlet and exhaust valves. Guide bushings exhaust valves have a larger internal diameter and shorter, making them easy to sort out. Stretching across the sleeve soaked rags in gasoline, Clean bushings. Valve stems are best cleaned rotating wire brush attached to an electric drill.

Checking wear on guides carried by a calibrated mandrel. If vybrakovochny swage free entry to the guide sleeve, the sleeve should be replaced with a new one. To remove the plugs should be used with special mandrel shoulder. If there is the possibility of using guides 1 standard size, to fit them using a special holder, by means of which the guide sleeve is pressed into the receiving hole as long as the locking ring enters into a groove on the cylinder head. When installing the repair guides landing slot size groups must be pre-treated with lingering manual scans. Since the guides before pressing must be cooled with dry ice, be sure to pass the cylinder head at the station for the installation of new guides.

Before replacing the valve guides, first check the general condition of the cylinder head. After pressing the sleeve bore to the desired size: 8,00-8,015 mm for the intake valves and exhaust valves 9,00-9,015. Guide bushings exhaust valves have a greater length.

When replacing the guides need to be replaced and valves and valve seats - abraded.

Valve seat

If the camshaft bearings are worn out, then in this case there is no need to bore the valve seat, and should be replaced by the cylinder head assembly. Saddle valves are checked for wear and the formation of shells. Small traces of wear can be avoided by milling using a 45-degree bevel cutter. If the valve seat due to the great development has become very broad, such seat must be replaced. The valve seat is pressed into the cylinder head, and take their best by drilling or twisting with special bores. It should be very careful not to damage the cylinder head. Measure the diameter of the base hole D1 (Fig. 37) and if necessary to chisel until next repair size. The valve seat to maintenance allowances can bore up until no overlap will provide the prescribed 0,068-0,10 mm. Saddles intake valves have a larger diameter.

Cylinder head in a water bath heated to 90 ?� C, and the valve seat to cool on dry ice, after which it will be possible to press in a special holder in the mounting slot. This operation is recommended in the workshop.

Edit countersink corresponding valve seat and valve grinding wheel on a grinding machine. Using the measured maximum distance of the valve A, as shown in the lower part of Fig. 38. When installing new valves and valve seat distance A should be 0.1-0.5 mm. The wear limit is 1.0 mm.

After treatment, measure the width of the sealing valve seat belts. If the width of the sealing inlet valve seat belt is different from the value 2.5 mm, and the seat of the exhaust valve - the value of 3.5 mm, it is necessary to process such a saddle-degree cutter 15 at the top of the 60 ?� and the bottom of the mill. Milling is terminated when the width of the sealing valve seat belt included in the above range. After milling is necessary to perform lapping valve seats. For this purpose, the valve seat is applied to a small number of grinding paste. On top of the valve head attached sucker, through which the valve communicate rotational movement in one direction and then in the other direction (Fig. 39). From time to time it is necessary to turn the valve a quarter turn, and then grind rotary motion. If necessary, it is necessary to add a grinding paste on the valve seat. After lapping, remove the residue with a valve seat and valve control landing on the saddle and head. On both sides must be clearly visible resulting matte belt, which determines the width of the sealing valve seat belts.

Pencil, apply a few dashes in the acquired frosted girdle at intervals of 1 mm around the perimeter. Thereafter, a lower valve seat and rotate it through 90 ?� around a rod, slightly pressing the valve seat.

Remove the valve from the seat and make sure the pencil marks have disappeared. If the width of the sealing valve seat belt is in the prescribed range, the cylinder head can be mounted on the engine. Otherwise, you must continue treatment and grinding saddles or replace the cylinder head.

Valves

Due to the use of hydraulic valve clearance compensator end of the valve rod intake and exhaust valves are subjected to a special treatment in order to withstand the increased loads. Slight damage on the heads of the valves can be removed by lapping them to saddles, as described above. More serious damage to the sealing surfaces can be fixed on the valve grinder. On the polished thickness of the valve edges of plates shall not be less than 0.5 to 0.7 mm for the inlet valves and 0.5-0.6 mm - for the final.

In these types of engine valves without using sodium filling, as was the case in other types of engines the company Mercedes-Benz. In Fig. 40 shows the dimensions of the valve. Valves whose dimensions do not meet the size, should be replaced with new ones.

When ordering valves should always indicate their purpose (intake or exhaust), and that these valves are designed for the diesel engine.

In some cases it is possible to replace only the exhaust valves, if they have, for example, burned edges.

Cylinder Head

Thoroughly clean the gasket surface of the cylinder head and cylinder block, and then check the cylinder head in the absence of deformation. To this end, the mounting surface of the cylinder head and to place the line via the probe to measure the gap below the ruler longitudinal transverse and diagonal directions. If in the process of measuring the gap between the line and the surface of the cylinder head in the longitudinal direction exceeds 0.10 mm, then the cylinder head should be referred to specialized service stations. When installing the line in the transverse direction of the cylinder head under the line there should be no clearance. Cylinder heads can be sanded up until the appropriate height adjustment valves will do this (size A in Fig. 38).

Similarly, you need to check the height of the protruding part of the settling chamber for diesel fuel injection (601 minutes drive). The edge of the settling chamber must act on 7,6-8,1 mm.

On HUNDRED prescribed size of the settling chamber of the protruding portion can be set using a set of gaskets of different thicknesses, mounted under the prechamber. This work must necessarily be carried out in the workshop, as it requires a special tool for removing and installing the settling chamber.

Camshaft

The following text describes the work related to the inspection and control of the camshaft. Constructive description of a camshaft see. Sec. 2.12.6. The camshaft is installed on the prism, the substituted under extreme neck support or clamp between the centers of the lathe, as shown in Fig. 41, and the reference to the average neck to bring the probe measuring the indicator. Then, slowly turning the camshaft, it is necessary to follow the indications of the arrow. If the needle is deflected over the division of 0.01 mm, it will mean that the shaft is deformed and must be replaced.

Replacing the valve stem seals (cylinder head mounted on the engine)

Valve stem seals can be found in the repair kit. The composition of the repair kit includes protective sleeves which are put on the mounting rods of the intake valves. Valve stem seals for intake and exhaust valves are different from each other as their diameters and form, so it is impossible to mix them up (Fig. 42).

To install the caps typically used a special tool. If it is not at hand, you can use a thin tube, but be very careful not to damage the seals and locking springs caps. When installing the valve stem seals on the valve stems, the latter must be removed crackers and valve springs. To eliminate the drop in the valve cylinder is necessary that the piston of the cylinder is at TDC. On the four-cylinder engines, this operation is greatly facilitated by the fact that whenever two pistons are at TDC. In the five-cylinder engine do the job a little more difficult, because every time you need to rotate the crankshaft of the engine at a certain angle, setting another cylinder piston at TDC. Replace the valve stem seals should be performed as follows (we recommend to entrust the job done experienced).

Scroll to the engine installation of the piston of the first cylinder in the TDC.

Remove the camshaft (Sect. 2.12.6).

Remove biscuits valves of the first cylinder, as described in Section. 2.4.2. On the four-cylinder engine can simultaneously remove crumbs and remove the valve springs with the valve of the fourth cylinder.

Carefully, so as not to damage the cores of valves and openings pushers, pliers to pull off the old valve stem seals.

The new valve stem seals lubricated and gently push down on the valve stem. Do not forget to put on the rods of the intake valves protective sleeve. Tightly implant stem seals on the valve guides.

Install the valve springs color-coded and set down the crackers of the valve, making sure that the crackers got well into the grooves and conical recess upper support plates valve springs.

Gently lift the camshaft drive sprocket to the chain is not disengaged, and crank four-cylinder engine on the half-turn. After this change may be similarly stem seals on the valves of the second and third cylinders. When operating on a five-cylinder engine crankshaft must rotate until the next cylinder until the piston reaches TDC. Alternating subsequent cylinder, the piston of which passes TDC: 2-4-5-3. As noted above, the carrying out of this work requires special care.