Overhaul
REMOVAL1. Remove the crank pulley.
2. Remove the front chain cover.
3. Remove the timing chain assembly.
4. Remove the cam sprocket.
5. Remove the crank sprocket.
6. Remove the rear chain cover.
7. Remove the camshaft.
8. Tighten the cylinder head bolts in the numerical order as shown in the figure.
Leave bolts (2) and (4) engaged by three or four threads to prevent the cylinder head from falling.
9. While tapping the cylinder head with a plastic hammer, separate it from cylinder block.
10. Remove the bolts (2) and (4) to remove the cylinder head.
11. Remove the cylinder head gasket.
CAUTION: Be careful not to scratch the mating surface of cylinder head and cylinder block.
12. Similarly, remove the cylinder head (RH).
INSTALLATION
1. Install the cylinder head and gaskets on cylinder block.
CAUTION:
^ Use new cylinder head gaskets.
^ Be careful not to scratch the mating surface of cylinder head and cylinder block.
2. Tighten the cylinder head bolts.
a Apply a coat of engine oil to washers and cylinder head bolt threads.
b Install the cylinder head to cylinder block, and then tighten the bolts with torque of 20 Nm (2.0 kgf-m, 14 ft. lbs.) in numerical sequence as shown in the figure.
c Tighten the bolts with torque of 50 Nm (5.1 kgf-m, 37 ft. lbs.) in numerical sequence as shown in the figure.
d Back off all bolts by 180° in reverse order of installation, and back them off again by 180°.
e Tighten the bolts with torque of 20 Nm (2.0 kgf-m, 14 ft. lbs.) in numerical sequence as shown in the figure.
f Tighten the bolts (1)-(4) with torque of 48 Nm (3.5 kgf-m, 35.4 ft. lbs.) in numerical sequence.
g Tighten the bolts (5)-(8) with torque of 44 Nm (4.5 kgf-m, 33 ft. lbs.) in numerical sequence.
h Tighten the bolts 90° in the numerical order as shown in the figure.
i. Tighten the bolt (1)-(4) 45° in the numerical order.
3. Install the camshaft.
4. Install the rear chain cover.
5. Install the crank sprocket.
6. Install the cam sprocket.
7. Install the timing chain assembly.
8. Install the front chain cover.
9. Install the crank pulley.
DISASSEMBLY
1. Set the cylinder head on ST.
ST 18250AA010 CYLINDER HEAD TABLE
2. Remove the valve lifter.
3. Set the ST on valve spring retainer. Compress the valve spring and remove the valve spring retainer key. Remove each valve and valve spring.
ST 499718000 VALVE SPRING REMOVER
NOTE: Keep all the removed parts in order for re-installing in their original positions.
CAUTION:
^ Mark each valve to prevent confusion.
^ Use extreme care not to damage the lips of the intake valve oil seals and exhaust valve oil seals.
ASSEMBLY
1. Installation of valve spring and valve:
a. Set the cylinder head on ST.
ST 18250AA010 CYLINDER HEAD TABLE
b Coat the stem of each valve with engine oil and insert the valve into valve guide.
NOTE: When inserting the valve into valve guide, use special care not to damage the oil seal lip.
c Install the valve spring and retainer.
NOTE:
^ Be sure to install the valve springs with their close-coiled end facing the seat on the cylinder head.
^ Install the valve spring with the painted side facing to retainer.
d Set the ST on valve spring.
ST 499718000 VALVE SPRING REMOVER
e Compress the valve spring and fit the valve spring retainer key.
f After installing, tap the valve spring retainers lightly with a wooden hammer for better seating.
2. Apply oil to the surface of the valve lifter and valve shim.
3. Install the valve lifter and valve shim.
INSPECTION
CYLINDER HEAD
1. Make sure that no crack or other damages do not exist. In addition to visual inspection, inspect important areas using liquid penetrant tester. Check that there are no marks of gas leaking or water leaking on gasket installing surface.
2. Set the cylinder head on ST.
ST 18250AA010 CYLINDER HEAD TABLE
3. Measure the flatness of the cylinder head surface that mates with crankcase using a straight edge (A) and thickness gauge (B).
Flatness:
Standard 0.02 mm (0.0008 inch)
Standard height of cylinder head: 124 ± 0.05 mm (4.88 ± 0.0020 inch)
NOTE: Uneven torque for the cylinder head nuts can cause warping. When reinstalling, pay special attention to the torque so as to tighten evenly.
VALVE SEAT
Inspect the intake and exhaust valve seats, and correct the contact surfaces with a valve seat cutter if they are defective or when valve guides are replaced.
VALVE GUIDE
1. Check the clearance between valve guide and stem. The clearance can be checked by measuring respectively the outer diameter of valve stem and inner diameter of valve guide with a micrometer.
Clearance between the valve guide and valve stem:
Standard
Intake 0.030 - 0.057 mm (0.0012 - 0.0022 inch)
Exhaust 0.040 - 0.067 mm (0.0016 - 0.0026 inch)
2. If the clearance between valve guide and stem is out of standard, replace the valve guide or valve itself whichever shows greater amount of wear or damaged and etc. See the following procedure for valve guide replacement.
Valve guide inner diameter: 5.500 - 5.512 mm (0.2165 - 0.2170 inch)
Valve stem outer diameters:
Intake 5.455 - 5.470 mm (0.2148 - 0.2154 inch)
Exhaust 5.445 - 5.460 mm (0.2144 - 0.2150 inch)
a Place the cylinder head on ST1 with the combustion chamber upward so that valve guides enter the holes in ST1.
b Insert ST2 into the valve guide and press it down to remove the valve guide.
ST1 18250AA010 CYLINDER HEAD TABLE
ST2 499765700 VALVE GUIDE REMOVER
c Turn the cylinder head upside down and place the ST as shown in the figure.
ST 18251AA040 VALVE GUIDE ADJUSTER
d Before installing a new valve guide, make sure that neither scratches nor damages exist on the inside surface of the valve guide holes in cylinder head.
e Put a new valve guide, coated with sufficient oil, in cylinder, and insert the ST1 into valve guide. Press in until the valve guide upper end is flush with the upper surface of ST2.
ST1 499765700 VALVE GUIDE REMOVER
ST2 18251AA040 VALVE GUIDE ADJUSTER
f Check the valve guide protrusion.
Valve guide protrusion L: 11.4 - 11.8 mm (0.449 - 0.465 inch)
g Ream the inside of valve guide using ST. Put the reamer in valve guide, and rotate the reamer slowly clockwise while pushing it lightly. Bring the reamer back while rotating it clockwise. After reaming, clean the valve guide to remove chips.
ST 499765900 VALVE GUIDE REAMER
NOTE:
^ Apply engine oil to the reamer when reaming.
^ If the inner surface of the valve guide is torn, the edge of the reamer should be slightly ground with an oil stone.
^ If the inner surface of the valve guide becomes lustrous and the reamer does not chip, use a new reamer or remedy the reamer.
h Recheck the contact condition between valve and valve seat after replacing the valve guide.
INTAKE AND EXHAUST VALVE
1. Inspect the flange and stem of valve, and replace if damaged, worn or deformed, or if "H" is exceed the standard value or offset wearing is emitted.
H:
Intake (A)
Standard 1.0 mm (0.039 inch)
Exhaust (B)
Standard 1.2 mm (0.047 inch)
2. Put a small amount of grinding compound on the seat surface and lap the valve and seat surface. Install a new intake valve oil seal after lapping.
VALVE SPRING
1. Check the valve springs for damage, free length, and tension. Replace the valve spring if it is not within the standard value presented in the table.
2. To measure the squareness of the valve spring, stand the spring on a surface plate and measure its deflection at the top of spring using a try square.
INTAKE AND EXHAUST VALVE OIL SEAL
In the following case, pinch and remove the oil seal from valve using pliers, and then replace it with a new one.
^ When the lip is damaged.
^ When the spring is out of the specified position.
^ When readjusting the surfaces of intake valve and valve sheet.
^ When replacing the intake valve guide.
1. Set the cylinder head on ST1.
2. Press-fit the oil seal to the specified dimension indicated in the figure using ST2.
ST1 18250AA010 CYLINDER HEAD TABLE
ST2 499585500 VALVE OIL SEAL GUIDE
NOTE:
^ Apply engine oil to oil seal before force-fitting.
^ When press-fitting the oil seal, do not use a hammer or strike in.
VALVE LIFTER
1. Check the valve lifter visually.
2. Measure the outer diameter of valve lifter.
3. Measure the inner diameter of valve lifter hole of cylinder head.
NOTE: If difference between outer diameter of valve lifter and inner diameter of valve lifter hole is out of the standard or offset wearing is emitted, replace the cylinder head.
Standard: 0.019 - 0.057 mm (0.0007 - 0.0022 inch)