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Repair of the cylinder head
Checking valve springs
| Fig. 396. Valve parts: 1 - a pusher plate; 2 - half of the conical valve face; 3 - the top plate of the valve spring; 4 - external valve spring; 5 - internal valve spring; 6 - lower seat valve spring; 7 - stem seal; 8 - the directing plug of the valve; 9 - cylinder head; 10 - camshaft oil seal; 11 - Valves
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Check the valve springs in the same way as for a gasoline engine (valve components shown in Fig. 396). Valve guides
| Fig. 397. Check the indicator of the gap of the valve stem in the valve guide
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Set indicator, as shown in Fig. 397, and insert the valve. Shake the plate valve at the top of from side to side and check the indicator. If the resulting value is greater than 1.3 mm, replace the valve guide. Since the difference in size between the intake and exhaust valves is very low, be very careful not to confuse the intake and exhaust valves and insert them only in the appropriate holes. Can be used after grinding the cylinder head, if it has abrasion between the valve seats, provided that scratches no wider than 0.5 mm. To replace the valve guide sleeve squeeze out the old with a suitable mandrel by the camshaft cylinder head. If you notice that the valve guides are bound, they should squeeze from the combustion chamber (replaced bushings are screwed fastening). The cylinder head may be heated in order to facilitate this work. On designed to drive out the valve guide pin punch screw that fits the size of the inside of the valve guide. If you need to replace the valve guide, then with her and replace the valve itself. Then grind the valve seats. The new valve guides and oil the good 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. Pressure Joining thus should not be more than 1 m, since otherwise the collar may be cut. The valve guide after pressing a special treat scan. Guide bushings intake and exhaust valves treat scan 8.0 mm. It will automatically obtain the correct gap valve guides.
A warning If you have replaced the valve guides, the valve seat must be milled. |
The valve seat
| Fig. 398. The view of the valve seat (measurement values are shown in the table shows the adjustments and control.): A - the diameter of the valve seat; b - the diameter of the valve head; c - the width of the valve seat
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Saddle valves are processed in accordance with the shown in Fig. 398 dimensions. Inspect all valve seats for wear and scratches. Light wear can be removed by the cutter (45 ?�). If the seat is badly worn, valve seats otfrezeruyte again. As has been said, if the bushings were replaced with valves, the valve seat, be sure to grind. Perform the following measurements to determine the amount of additional processing to the valve seat: - Insert the valve in its guide sleeve and press on the valve seat;
| Fig. 399. The depth measurement with a valve seat to further processing (indicated by arrows)
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- Measure the interval and (Fig. 399), between the top of the valve and the upper edge of the cylinder head; - Calculate the maximum and minimum allowable value after cutting the measured value. On the intake valve, it should be 35.8 mm for the exhaust - 36.1 mm. If the measured value subtracted the minimum distance, it will get the maximum permissible value. It will be important during the work described below. Valve seats should be milled in the case were given new guides. To do this: - Treat mill at 45 ?�, and then the cutter 15 ?� angled upper edge of the valve seat (see. Fig. 398) to reduce the width of the valve seat and bring it to a 2.7 mm - for the inlet and 2.05 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; - So as not to squander the valve seats in the cylinder head too much, be sure to make the above measurements;
- Sand the machined valve seats. To do this, apply a small amount of the valve seat lapping compound and install valves in the saddle. Rotational movement back and forth (Fig. 400) make grinding; - After grinding thoroughly clean all parts of the mud and lapping compound and check valve seat in place of the valve disc and O-ring. It must be seen continual 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 a sealing ring. 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 Slight damage to the surface of plates of valves can be repaired by lapping the valves in the saddle of the cylinder head, as already described.
| Fig. 401. The main valve sizes. The exact value should be seen in the table of adjustment and control. The value of d may not be less than the minimum value of this nominal size: a - diameter of the valve disc; b - the diameter of the valve stem, c - the length of the valve; d - the edge of the valve plate; a = 45 ?�
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Perform measurements (Fig. 401), and replace any that do not meet the size of the valves. The values corresponding to the designations a, b and c, you can take from the table of tolerances and control. If the ends of the valve stems are worn, they can be ground on the grinding machine under the condition that will be removed during grinding of not more than 0.5 mm material. Plates intake valves can be ground to the grinding machine for valves, with the proviso that the value of b (see. Fig. 401) is not less than 0.5 mm. Grinding machine for unacceptable exhaust valves, since they are made of special material. Only by lapping paste can again result in the exhaust and intake valves in the normal or otherwise to replace them. Cylinder Head
| Fig. 402 Checking cylinder head for distortion using a ruler and measuring probe
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Thoroughly clean the mating plane of the cylinder head and cylinder block and check the surface of the cylinder head deformation. To do this, put on the head of the measuring range (Fig. 402) and using the probe check clearance along, across and diagonally. If the probe can be inserted more than 0.1 mm, the cylinder head must be polished. If the clearance is in any place more, the cylinder head must be replaced, since the removal of the metal layer more unacceptable. Deformation of the surface of the cylinder head may occur, for example if the engine overheats. Camshaft
| Fig. 403. Checking the heartbeat of a camshaft
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To determine the wear of the camshaft, hold it, as shown in Fig. 403, and set the indicator on the neck of the central bearing. If the instrument will show a deviation greater than 0.01 mm, the camshaft is deformed and must be replaced. Check the neck of a camshaft for damage.
| Fig. 404. Measurement of an axial backlash of a camshaft
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To measure the axial clearance of camshaft insert camshaft into the cylinder head (without pushers) and secure it with extreme bearing caps. Install the cylinder head on a smooth surface. Set the indicator on the front surface (Fig. 404) and move the shaft back and forth in the direction of the axis. The gap must not be greater than 0.15 mm. Otherwise worn bearing surface of the bearing cap.
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