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OVERHAULING CYLINDER HEAD


AIM:

  OVERHAULING CYLINDER HEAD ASSEMBLY

TOOLS REQUIRED:

1. 12-13mm RING SPANNER
2. BOX SPANNER SET
3. VALVE GRINDING STICK
4. FEELER GAUGE
5. SCREW DRIVER (-, +)
6. VALVE LIFTER, TORQUE WRENCH
7.CAM GEAR PULLER

MATERIALS REQUIRED

1. KEROSENE OIL
2. COTTON WASTE
3. GRINDING PASTE
4. EMERY PAPER
PROCEDURE

DISMANTLING 

1. Ensure that the cylinder head does not tilt while removing, so as to avoid damage to the cylinder head studs.

2. Place the cylinder head on a workbench over two wooden block stands.

3. Remove rocker arm assembly the cylinder head.

4. Remove the cylinder head gasket and keep it in a safe place.

5. Press the valve spring with the help of the special tool.

6. Take out the cotters locks/collets using the special tool. Release the valve spring and take out the special tool. Remove the spring, and the valve and retainer.

7. Keep the valves in order. Number the valves.

 Cleaning and inspection

1. Clean exhaust manifold with solvent (caustic soda) and pressurised water.

2. Clean inlet manifold.

3. Clean the valves, springs and spring retainers, cotters and head surfaces using kerosene.

4. Remove the carbon deposits, using a wire brush, from the valve seats and combustion chamber's surroundings.

5. Check the surface flatness of the cylinder head.

6. Check the cylinder head surface visually for pitting and cracks.

7. Inspect the valve stem for bend, using a 'V' block and dial gauge.

8. Check the valve face visually, for pitting and damage. If necessary grind and lap.

9. Check the cotter collar for damage.

10. Check inlet and exhaust manifold visually for any crack, damage.

11. Check the valve spring for tension, on a spring tester.

12. Check the valve spring, for breakage/damage.


ASSEMBLING

1. Oil the valve stem.

2. Insert the valve in the valve guide.

3. Support the valve poppet, so that it is held firmly on its seat.

4. Fit the valve spring washer on the cylinder head.

5. Insert the valve spring.

6. Place the valve spring retainer over the spring.

7. Compress the valve spring with the special tool.

8. Insert cotters with the smaller dia. at the bottom and release pressure on the valve springs gradually. Slightly tap the valve stem with a mallet to ensure that the cotters have locked the valves and spring retainers.

9. Take care that the two halves of the cotters are centrally located

10. Check the valve leakage using the special tool. Attach a suction cup  with a suction bulb and vacuum gauge on the cylinder head, covering the valve seat. Create a vacuum with the help of the suction bulb (rubber bulb). Wait for 3 minutes and note any drop of vacuum on the gauge. If there is any drop in vacuum, the valve seat is leaky and requires lapping.

11. Fit inlet manifold.

12. Fit exhaust manifold.

OVERHAULING ROCKER ARM ASSEMBLY

1. Remove the lock - screw/cir clips at both ends of the rocker shaft.

2. Remove the rocker levers rocker lever bracket, springs and spacers from the rocker shaft and tie them in a rope in sequence.

3. Remove the rocker bracket which supplies oil to the rocker shaft from the cylinder head. The position of the bracket varies from one make to another.

4. Clean all the parts in kerosene.

5. Check the tension of the rocker spring. Replace it, if necessary.

6. Check visually the rocker lever for cracks, pitting on tips. Check the condition of the threads by screwing the adjusting screw in threads.

7. Check the rocker shaft  visually for cracks and damage.

8. Check the rocker arm bushing for wear and tear and alignment of lubricating holes.

9. Check the rocker arm ball pins  for wear and damage.

10. Check the push - rod  for bend and the socket end for wear.

11. Clean the base of the rocker shaft supports, and the seats on the cylinder head.

12. Fix the ball pins on the rocker arm.

13. Insert the inlet and exhaust rocker lever, spring and the distance piece between the two rocker shaft supports in the rocker arm shaft.

14. Loosen the ball pin's  nuts, to ensure that the push - rods do not bend, while tightening the rocker shaft support bracket's nuts and bolts on the cylinder head.

15. Checking flatness of cylinder head surface.

16. Clean the surface to be checked.

17. Place part on a plain surface, so that surface, to be checked, faces upward.

18. Keep the straight edge on surface.

19. Insert the feeler gauge's  leaves between the straight edge and the surface.

20. Note down the thickness of the thickest leaf/leaves which can be inserted between the straight edge and the surface. This thickness gives the maximum face out in that distorsion.

21. Repeat above steps in 4 directions and note down the maximum distorsion in all the 4 directions.

22. If necessary reface it.

RESULT :

 Overhauling of cylinder head  assembly done successfully.
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