Cylinder Head Assembly: Service and Repair

DISASSEMBLY
REMOVAL PARTS
Arrange removal parts according to cylinder numbers, intake and exhaust valves.

Removal of cylinder head bolts
Remove the cylinder head bolts using the hexagonal wrench.

Removal of the retainer lock





1. Compress the valve spring using SST (09222-28000, 09222-28100).
2. Remove the retainer lock.

Valve stem seal





Do not reuse the valve stem seal.

INSPECTION
CYLINDER HEAD
1. Remove scale, sealing compound and carbon deposits completely. After cleaning oil passages, apply compressed air to make certain that the passages are not clogged.
2. Visually check the cylinder head for cracks, damage or water leakage.





3. Check the cylinder head gasket surface for flatness with a straight edge and feeler.

INSTALLATION
CYLINDER HEAD GASKET
1. All mating faces for the gasket on the cylinder block and the cylinder head should be cleaned.





2. Install new cylinder head gasket on the cylinder head assembly. Do not smear the sealant on the gasket and only the new gasket must be used.

CYLINDER HEAD BOLT





1. Tighten the cylinder head bolt in the picture using the so-called special tool "head bolt wrench".

VALVE INSPECTION
VALVES





1. Clean the valve with wire brush.





2. Inspect wear and damage of each valve, and bending of the head and stem at "If" part which is at the end of valve has hollow or wear, replace the valve. If margin is smaller than service standard, replace the valve.

VALVE SPRINGS
1. Check free height of each valve spring and replace if necessary.





2. Using a square, test squareness of each valve spring. If spring is excessively out of square, replace it.

VALVE GUIDE





Check the valve stem-to-guide clearance. If the clearance exceeds the service limit, replace the valve guide with a new oversize guide.

VALVE SEAT INSERT





Inspect for any trace of overheating and the contact state of valve face. If necessary, repair or replace it. When repairing, inspect for wear in the valve guide. If the guide is worn, replace it and adjust the seat ring. Adjust the valve seat with grinder or cutter making valve seat contact width from the center of valve face be in the specified value. When adjusting the exhaust valve seat, use the valve seat cutter or pilot. After adjustment, lapping process be made by using applying compound on the valve and valve seat.

PROCEDURE FOR REPLACEMENT OF VALVE SEAT INSERT








1. If the valve seat insert is excessively worn, cut out the insert wall using valve seat cover at normal temperature like "A" shown in the picture.
2. After removing the seat insert, match the seat insert bore using a reamer or cutter to the indicated size.
3. Heat the cylinder head up to 250°C and press in an oversize seat insert. At this time, the temperature of oversize seat insert must be the same as the room temperature. When new valve seat is installed, adjust the valve seat face.

PROCEDURE FOR REPLACEMENT OF VALVE GUIDE
As the valve guide is tightly pressed in, replace the valve guide as following procedure, using the valve guide installer or appropriate tools.
1. Using the push rod of the valve guide installer, push it out of initial position by pushing it to the cylinder block side.
2. Machine insert hole of the cylinder head valve guide in the size of oversize valve guide.





3. Press in the valve guide using the valve guide installer or appropriate tools. By using the valve guide installer, it can be pressed in the specified height.





4. Valve guide is to be installed from the upside of the cylinder head.
As length of the intake valve guide is different from that of the exhaust valve guide, be careful. (The lengths of guide for intake valve and exhaust valve are 45.5 mm and 50.5 mm respectively.)
After installing the valve guide, insert the new valve and check sliding state.
5. When the valve guide is replaced, inspect for valve contact state. If necessary, adjust the valve seat.





VALVE GUIDE INSERT OVERSIZES

INSTALLATION
VALVE STEM SEAL
1. Install the valve spring seat.





2. Install a new stem seal on valve guide using the special tool (09222-28200).





CAUTION: Valve stem seal should never be reused.
Incorrect seat installation can cause oil leakage through lower part of the valve guide. When the valve stem seal is removed due to missing of valve spring seat, the stem seal cannot be reused.

VALVE SPRING





Install the valve spring so that the end part with identification mark is paced at the end of the spring retainer.

RETAINER LOCK





Insert the retainer lock by pressing down the valve spring with special tool (09222-28000).