Cleaning
2. Clean off all traces of the old gasket from the cylinder head.
3. Remove carbon deposits from combustion chambers and holes, then thoroughly flush the cylinder head with kerosene or a suitable solvent. Scrape most of the carbon off the valves, then use a wire brush to remove any remaining carbon from the valve heads and stems.
4. If the head is extremely dirty, it must be steam cleaned. Finally, remove all plugs and clean all oil holes and oil passages. Then, using a suitable sealant, install the new oil port plugs in place in the cylinder head.
Inspection
Attention! Perform all inspection procedures before concluding that it is necessary to go to an auto repair shop for regrinding. Make a list of all components that require processing.
Cylinder head
5. Carefully inspect the head for cracks, other damage, and coolant leaks. If cracks are found, replace the head.
6. Use the edge of the ruler and feeler gauge to make sure that the surface of the cylinder head is not deformed (see illustration). The surface of the head can be reground, but provided that the height of the cylinder head does not become less than specified in Specifications values.
7. Inspect the valve seats in each of the combustion chambers. If they are badly pitted, cracked, or burnt, have them resharpened by a professional. If pitting is minor, it can be removed by grinding the valve head and seat with a special fine paste as described below.
8. If the valve guides are worn (valve moves horizontally), replace them. Measure the diameter of existing valve stems (see below) and the inner diameter of the guide bushings, then calculate the gap and compare it with the regulated value. If clearance does not match Specifications, replace valves and/or guides as needed.
9. It is best to have the valve guides replaced by an engine repair specialist. When installing a new guide, first place it in the refrigerator for at least an hour, then insert it into the hole in the head on the camshaft side until the sleeve protrudes above the surface of the cylinder head to the height specified in the Specifications.
10. If it is necessary to regrind the valve seats, this should only be done after the guide bushings have been replaced.
Valves
Attention! On 3.0L engines, the exhaust valves are filled with sodium and must therefore be handled with care. Remember that sodium reacts very violently with water.
11. Inspect each valve head for pitting, burn marks, cracks, or other signs of wear, and check the valve stem for scratches and gouges. While rotating the valve, carefully check it for signs of deformation. Inspect the end of each stem for pitting and signs of excessive wear. Damaged or worn valves must be replaced.
12. If the condition of the valve seems to be satisfactory, measure the stem diameter in several places with a micrometer (see illustration). Any significant difference in the data obtained indicates wear on the valve stem, which means the valve must be replaced.
13. If the valves are not damaged, they should be lapped to ensure a tight fit to the seats. If pitting is minor, use only fine-grained lapping paste.
14. Lapping of valves is performed as follows. Place the cylinder head upside down on a workbench.
15. Apply an appropriate grade of lapping paste to the valve seat surface and attach the special suction cup to the valve head. Rotating the valve back and forth half a turn, grind its head, lapping it against the seat, occasionally lifting the valve to redistribute the paste (see illustration). Installing a weak spring under the valve head will greatly facilitate the work.
16. If a coarse grinding paste is used, work until the seat and valve contact surfaces are dull, then wipe off the compound and repeat the process with a fine paste. When the seat and valve surfaces are a uniform light gray color, lapping is complete. Do not lap the valves longer than necessary, as this will cause the seat to dig into the cylinder head undesirably.
17. When all valves are lapped, carefully wash off all traces of grinding paste using kerosene or a suitable solvent.
Valve components
18. Inspect the valve springs for signs of damage and discoloration, and measure their free length with a caliper or steel ruler, or compare with a new spring.
19. Place each spring on a flat surface and check them for deformation using a corner. If any of the springs are damaged, distorted, or loose, purchase a new complete set of springs. It is recommended that the springs be replaced each time they are removed during an engine overhaul, regardless of their condition.
Visitor comments