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Inspection, testing and repair of cylinder head
After dismantling the cylinder head to wash out all details in gasoline. Clean the combustion chamber and valves from scale.
Check with a metal ruler and probe, if not broken the plane of the head adjacent to the cylinder block. Putting an edge line on the surface of the head along the transversely and diagonally in different locations and measure probe gap between it and the plane of the head. If the gap is greater than 0.1 mm, the head needs to be refinished.
Measuring the height of the cylinder head a) The engine capacity of 1.1 liters and 1.3; | b) MH and 2G engines of 1.6 and 1.8 liters |
Minimum permissible height of the cylinder head:
- For engines MN and 2G between the upper and lower planes of 135.6 mm;
- For the rest of the engine between the bottom edge of the hole under the camshaft oil seal and the lower plane of 119.3 mm. If the height of the grinding head unit receive less than this, the head must be replaced. Check the lateral clearance between valve and guide bushings. To insert this valve guide sleeve so that the end of the valve stem is flush with the upper edge of the sleeve. Then, shaking the valve horizontally from stop to stop, an indicator to measure the amount of movement of the valve disc, which shows the gap. If the gap exceeds 1 mm for the inlet valves and plugs 1.3 mm plugs for graduation, the bushing should be replaced. Before press out the old guide sleeve, it is necessary to measure at what value it protrudes from the cylinder head, in order to also establish a new sleeve. Is extruded through the mandrel sleeve is necessary. Before pressing in the new guide sleeve to heat the cylinder head to 70 ?� C. Lubricate the hole in the head, and a new hub. Pressed into a new hub should be through the mandrel. Maximum permissible force pressing 1 m. After pressing sleeve to check and, if necessary, ream the hole under the valve.
Measure the distance (a) between the end of the valve stem and the top plane of the cylinder head
The size of the valve seat
| and - an outer diameter of the valve seat;
b - the distance from the surface of the cylinder head to the outer diameter of the seat;
a - the width of a working facet of the saddle;
z - the lower plane of the cylinder head |
Engines NC | The inlet valve | Exhaust valve | a = 32,2 mm | a = 26,5 mm | c = 2.0 mm | c = 2.4 mm | b = 2,55 mm | b = 2,85 mm | The remaining engines | The inlet valve | Exhaust valve | a = 34,8 mm | a = 27.8 mm | c = 2.2 mm | c = 2.2 mm | b = 9,2 mm | b = 9,6 mm |
Check the condition of the valve seats, they should not be signs of wear or erosion. If necessary grind the saddle. Sanding is made on a special grinding machine or a special machine. On engines with hydropushers valves when grinding is necessary to sustain the minimum size of "a" (see. Fig. Measure the distance between the end of the valve stem and the top plane of the cylinder head). The size of "a" for the inlet valves 35.8 mm for the exhaust - 36.1 mm. If the size of "a" is less than this, disrupt the normal operation of hydropushers. Reducing working facet of the valve seat, thus should not exceed the amount equal to the difference between the size "a" to the grinding and the minimum allowable value of the size "a". If grinding is not possible to restore the valve seats, they can be milled, followed by lapping valves. Dimensions valve seat shown in Fig. The size of the valve seat. The size of the valve | and - the diameter of the valve plate;
b - the diameter of the rod;
s - the length of the valve |
Engines NC | The inlet valve | Exhaust valve | a = 34.0 mm | a = 28,1 mm | c = 7.97 mm | c = 7,95 mm | b = 110,5 mm | b = 110,5 mm | The remaining engines | The inlet valve | Exhaust valve | a = 36,0 mm | a = 29.0 mm | c = 7.97 mm | c = 7.97 mm | b = 98,9 mm | b = 99,1 mm |
Check the condition of the valves. If a working facet of valves visible signs of wear or erosion, they must grind the seats. If the damage is significant working chamfer, chamfer the intake valves can be abraded. Working chamfer grind exhaust valves are prohibited, allowed only lapping. If lapping can not restore a working facet of the exhaust valve, it must be replaced. If a working facet of valves has deep scratches that can not be derived by grinding or lapping, and the valves are bent, burned or are cracked, the valves must be replaced. When handling the valve is necessary to sustain the specified dimensions (see. Fig. The size of the valve).
Lapping valve to the saddle
| PERFORMANCE ORDER | | 1. Push on the valve spring. | | 2. Apply a working facet of the valve lapping compound is a mixture of fine emery powder with engine oil. | | 3. Insert the valve spring in the head unit, the spring with the pressing needs of the valve seat. | | 4. Push on valve stem tool for grinding or valve plate a rubber sucker. | | 5. Turn the valve with a special tool or a suction cup on both sides, occasionally slightly pressing the valve seat. | | 6. When lapping is not removed from a working facet of the valve seat and too much metal as possible reduces the number of repairs and valve seat and thereby reduces their lifespan. | | 7. By the end of lapping need to reduce the amount of emery powder. When the lapped surface will be perfectly smooth, and will even gray, grinding out on clean engine oil. | | 8. outward sign of satisfactory grinding in is monophonic matte-gray working facet of the valve and seat. After lapping the valve seat and wipe with a clean cloth. | | 9. To check the tightness of a ground valve, install it into the head unit with a spring and crackers. After that, put the head on the side and pour into the channel, closing valve, kerosene. If over 10 minutes did not seep into the kerosene combustion chamber, the valve is considered sealed. |
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Check the condition of the valve springs. Springs having cracks or broken should be replaced. You can compare the height of the spring to the height of a new spring. If the spring has been removed from the engine, below the new, it needs to be replaced. Inspect valve levers. If there are noticeable wear at the contact lever with a cam camshaft, replace the lever. If the surface of contact with the valve lever noticeable dent the surface of the lever must be abraded. Inspect the camshaft. If cams and necks have deep scratches, or burrs generation, replace the shaft. Set shaft bearings cylinder head and measure the side clearance between the shaft and the mounting plate of the distributor of ignition (at engines MN and 2G - between the shaft and the bearing cover number 3). If the clearance is greater than 0.15 mm, replace the shaft or plate. To measure the diameters of the necks of a cam, which must be equal:
- Anterior neck - 31.45 mm;
- The average neck - 39.95 mm;
- Back neck - 40.45 mm. The maximum allowable wear necks of 0.25 mm. Camshaft engine MN to NU has cast a ring between the cams of the first cylinder. The diameter of the necks of a cam-shaft engines MN and 2G (with hydropushers valves) 26.0 mm, the minimum allowable size of the necks of 25.75 mm. If the measured diameter is less than acceptable, replace. Check the runout of the shaft, placing it on the prism, at an average neck. Allowable shaft runout 0.02 mm. If the reading is greater than, replace the shaft. Check and, if necessary, clean the oil channels in the shaft journal. To test the cylinder head for cracks, it is necessary to bring one of the openings of the cooling jacket hose for supplying compressed air. Plug all holes in the head with wooden plugs, lower head in a tub of water and supply air. In places where there are cracks, air bubbles will come out. Similarly, check oil passages in the cylinder head.
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