Master the Art of Cylinder Head Overhaul

Master the Art of Cylinder Head Overhaul

Table of Contents:

1. Introduction
2. Preparation for Cylinder Head Overhaul
3. Disassembly of Cylinder Head
4. Cleaning and Inspection
5. Overhaul of Valve Rotator
6. Replacement of Valve Seat
7. Reassembly of Cylinder Head
8. Clearance Adjustment of Suction and Exhaust Valves
9. Final Assembly
10. Conclusion

Introduction

In this article, we will discuss the procedure for the overhaul of a cylinder head. This process is essential for maintaining the performance and longevity of the engine. We will walk you through the step-by-step process of disassembling, cleaning, inspecting, and replacing components of the cylinder head. Additionally, we will cover the necessary adjustments and precautions to ensure proper functioning of the suction and exhaust valves. By following these instructions, you will be able to carry out an effective overhaul of the cylinder head and optimize the performance of your engine.

Preparation for Cylinder Head Overhaul

Before starting the disassembly of the cylinder head, it is important to prepare the necessary hydraulic tools. These tools will aid in the smooth disassembly and assembly process. Ensure that the hydraulic hose is tightly connected to the hydraulic pump and all the attachments are secure. Additionally, wrap the coupler with seal tape to prevent any oil leaks from the hydraulic tool.

Disassembly of Cylinder Head

1. Attach the hydraulic jack to the four cylinder head bolts, checking that it does not interfere with the adjacent cylinder head bolt.
2. Operate the hydraulic pump to increase hydraulic oil pressure to the specified value.
3. Loosen the tightening nuts of the cylinder head bolts by applying hydraulic oil pressure on the hydraulic jack.
4. Gradually release the hydraulic pressure by opening the relief valve of the hydraulic pump.
5. Once all the tightening nuts are loosened, remove the hydraulic jack and spacer.
6. Carefully remove the tightening nuts of the cylinder head bolts, ensuring not to damage the screw of the cylinder head bolt.
7. Use the exclusive lifting tool to remove the cylinder head vertically, taking caution not to damage the screws of the cylinder head bolts.

Cleaning and Inspection

After disassembling the cylinder head, it is essential to clean the carbon buildup in the cylinder liner or at the top of the piston. Use a descaling agent to thoroughly clean these areas. Additionally, cover the cylinder to prevent the entry of dust and foreign matter. Remove the suction and exhaust valve supporter from the detached cylinder head.

Overhaul of Valve Rotator

1. Disassemble the valve rotator into the body, ball plate, Belleville spring, and spring shoe by removing the circlip.
2. Wash the disassembled parts with washing oil and check for any abrasions or corrosion.
3. Replace any damaged parts and mark the rotator for easier monitoring during operation.

Replacement of Valve Seat

1. Check the valve seat for wear and replace it if it exceeds the usage limit.
2. If the valve seat is difficult to remove, use arc welding to build up the whole circumference of the valve seat face and remove it.
3. Insert a new valve seat, ensuring a quick and proper fit. Apply anti-seize and silicone-based liquid packing to the hole of the cylinder head before inserting the valve seat.
4. Conduct a hydraulic test to check for water leaks after replacing the exhaust valve seat.

Reassembly of Cylinder Head

1. Reassemble the cylinder head with any necessary replacements, ensuring all components are properly fitted.
2. Use the exclusive tool to install the stem seal, taking care not to damage the lip of the seal.
3. Apply lubricating oil to the suction and exhaust valves and insert them into the cylinder head.
4. Double-check the marking on the cylinder head to ensure correct placement.
5. Reassemble the valve rocker arm, spring, valve rotator, and cotter in the reverse order of disassembly.
6. Test the rotation of the valve rotator to ensure smooth operation.
7. Install the connecting pipe of the cooling water into the cylinder block and return the cylinder head to the engine, making sure to renew o-rings and replace the head and boost air packings.

Clearance Adjustment of Suction and Exhaust Valves

1. Set the piston of the cylinder to be adjusted at top dead center (TDC) of the compression stroke by turning the flywheel.
2. Loosen the lock nut and adjusting screw of the rocker arm and valve guard.
3. Tighten the adjusting screw of the valve guard slowly while holding its upper part to adjust the clearance to zero.
4. Fix the adjusting screw and tighten the lock nut securely.
5. Insert a feeler gauge to check the clearance between the adjusting screw of the rocker arm and valve guard. Adjust the clearance by tightening the adjusting screw gradually.
6. Retest the clearance by inserting the feeler gauge and ensure it can be easily removed.

Final Assembly

After adjusting the clearance of the suction and exhaust valves, proceed with the final assembly of all remaining components. Fix the tightening nut of the cylinder head using the hydraulic jack, following the same procedure as during the assembly. Reattach the fuel injection valve and all relevant pipes. Finally, ensure that everything is securely fastened and the cylinder head is restored to its original condition.

Conclusion

The overhaul of a cylinder head is a detailed process that requires careful disassembly, cleaning, inspection, and replacement of components. By following the step-by-step procedure outlined in this article, you can effectively carry out the overhaul and optimize the performance of your engine. Regular maintenance and attention to detail are key to ensuring the longevity and efficiency of your cylinder head.