Disassembly and Assembly
Components
Disassembly
CAUTION:
^ When installing sliding parts such as rocker arms, camshaft and oil seal, be sure to apply new engine oil on their sliding surfaces.
^ When tightening cylinder head bolts and rocker shaft bolts, apply new engine oil to thread portions and seat surfaces of bolts.
^ If hydraulic valve lifter is kept on its side, there is a risk of air entering it. After removal, always set hydraulic valve lifter straight up, or when laying it on its side, have it soak in new engine oil.
^ Do not disassemble hydraulic valve lifter.
^ Attach tags to valve lifters so as not to mix them up.
Exhaust Manifold Disassembly Sequence:
1. Remove the exhaust manifold from the cylinder head. Loosen the manifold bolts in the numerical order as shown.
2. Remove the rocker shafts with the rocker arms attached.
^ The rocker shaft bolts must be loosened in two or three steps.
3. Remove the hydraulic valve lifters and lifter guide.
^ Hold the hydraulic valve lifters with a wire so that they will not drop out of the lifter guide.
4. Remove the oil seal and camshaft.
^ Before removing the camshaft, measure the camshaft end play.
5. Remove the valve spring components using Tool as shown.
6. Remove the valve oil seals using Tool, or suitable tool.
Inspection
CYLINDER HEAD DISTORTION
1. Using a straight edge and a feeler gauge, measure the flatness variation of the sealing surface of the cylinder head.
Head surface flatness : less than 0.1 mm (0.004 inch)
2. If beyond the specified limit, resurface the cylinder head or replace it as necessary.
Resurfacing limit:
The resurfacing limit of cylinder head is determined by the cylinder block resurfacing.
Amount of cylinder head resurfacing is "A".
Amount of cylinder block resurfacing is "B".
The maximum limit is as follows : A + B = 0.2 mm (0.008 inch)
3. After resurfacing cylinder head, check that camshaft rotates freely by hand. If resistance is felt, cylinder head must be replaced.
Nominal cylinder head height : 106.8 - 107.2 mm (4.205 - 4.220 inch)
CAMSHAFT VISUAL CHECK
Check camshaft for scratches, seizure and wear.
CAMSHAFT RUNOUT
1. Support the camshaft at the No. 2 and No. 4 journals.
2. Measure the camshaft runout at the No. 3 journal.
Runout limit (total indicator : 0.1 mm (0.004 inch) reading)
3. If the runout exceeds the limit, replace the camshaft.
CAMSHAFT CAM HEIGHT
1. Measure the camshaft cam height.
Standard cam height
Intake and exhaust : 38.943 - 39.133 mm (1.5332 - 1.5407 inch)
Cam wear limit : 0.15 mm (0.0059 inch)
2. If the cam wear is beyond the limit, replace the camshaft.
CAMSHAFT JOURNAL CLEARANCE
1. Measure the outer diameter of the camshaft journal as shown.
Standard outer diameter
A : 46.920 - 46.940 mm (1.8472 - 1.8480 inch)
B : 42.420 - 42.440 mm (1.6701 - 1.6709 inch)
C : 47.920 - 47.940 mm (1.8866 - 1.8874 inch)
2. Measure the inner diameter of camshaft bearing to the corresponding positions of the camshaft in step 1.
Standard inner diameter
A : 47.000 - 47.025 mm (1.8504 - 1.8514 inch)
B : 42.500 - 42.525 mm (1.6732 - 1.6742 inch)
C : 48.000 - 48.025 mm (1.8898 - 1.8907 inch)
3. If the camshaft journal or bearing clearances exceed the limit, replace either the camshaft or the cylinder head, or both, as necessary.
Camshaft journal and bearing clearance limit : 0.15 mm (0.0059 inch)
CAMSHAFT END PLAY
1. Install the camshaft and the locate plate in the cylinder head.
2. Measure the camshaft end play.
Camshaft end play
Standard 0.03 - 0.06 mm (0.0012 - 0.0024 inch)
3. If the camshaft end play is out of the specified range, select the thickness of the camshaft locate plate to obtain the standard specified end play as shown.
Example: When the camshaft end play is 0.08 mm (0.0031 inch) with the camshaft locate plate No.1, replace the camshaft locate plate No.1 with the camshaft locate plate No.4 to set the camshaft end play at the specified 0.04 mm (0.0016 inch).
CAMSHAFT SPROCKET RUNOUT
1. Install the sprocket on the camshaft.
2. Support the camshaft at the No. 2 and No. 4 journals.
3. Measure the camshaft sprocket runout.
Runout limit (total indicator reading) : 0.1 mm (0.004 inch)
4. If the camshaft sprocket runout exceeds the limit, replace the camshaft sprocket.
VALVE GUIDE CLEARANCE
1. Measure the valve deflection in a right-angle direction with the camshaft as shown.
NOTE: The valve and valve guide mostly wear in this direction.
Valve deflection limit (dial gauge reading) : 0.20 mm (0.0079 inch)
2. If the valve deflection exceeds the limit, check the valve to valve guide clearance as shown.
a. Measure the valve stem diameter and the valve guide inner diameter.
b. Check that the clearance is within specification.
Valve to valve guide clearance
Intake : 0.020 - 0.053 mm (0.0008 - 0.0021 inch)
Exhaust : 0.030 - 0.049 mm (0.0012 - 0.0019 inch)
Limit : 0.10 mm (0.0039 inch)
c. If the valve to valve guide clearance exceeds the limit, replace the valve or valve guide as necessary.
VALVE GUIDE REPLACEMENT
1. To remove the valve guide, heat the cylinder head to 150° - 160°C (302° - 320°F) by soaking the cylinder head in heated oil as shown.
2. Drive out the valve guide with a press using a force under a 20 kN (2 ton, 2.2 US ton, 2.0 Imp. ton) of pressure, or use a hammer and a suitable tool as shown.
3. Ream the cylinder head valve guide hole as shown.
Valve guide hole diameter (for service parts)
Intake : 11.175 - 11.196 mm (0.4400 - 0.4408 inch)
Exhaust: 12.175 - 12.196 mm (0.4793 - 0.4802 inch)
4. Heat the cylinder head to 150° - 160°C (302° - 320°F) in heated oil and press the service valve guide into the cylinder head to the specified height as shown.
Height "L": 13.2 - 13.4 mm (0.520 - 0.528 inch)
5. Ream the new valve guides to specification.
Finished size
Intake : 7.000 - 7.018 mm (0.2756 - 0.2763 inch)
Exhaust : 8.000 - 8.011 mm (0.3150 - 0.3154 inch)
VALVE SEATS
Check the valve seats for any pitting at the valve contact surface, and re-seat or replace the valve seat if it has worn out.
^ Before repairing the valve seats, check the valve and valve guide for wear.
^ Use both hands to cut the valve seat uniformly as shown.
REPLACING VALVE SEAT FOR SERVICE PARTS
1. Bore out the old valve seat until it collapses. The machine depth stop should be set so that boring cannot continue beyond the bottom face of the seat recess in cylinder head
2. Ream the cylinder head valve seat recess.
CAUTION: Reaming should be done in circles concentric to the valve guide center so that valve seat will have the correct fit.
Reaming bore for service valve seat
Oversize : 0.5 mm (0.020 inch)
Intake : 44.500 - 44.516 mm (1.7520 - 1.7526 inch)
Exhaust : 37.500 - 37.516 mm (1.4764 - 1.4770 inch)
3. Heat the cylinder head to 150° - 160°C (302° - 320°F) by soaking it in heated oil as shown.
4. Press fit the valve seat until it seats on the bottom of the recess.
5. Cut or grind the valve seat using a suitable tool to the specified dimensions as shown.
6. After cutting the valve seat, lap the valve seat with an abrasive compound.
7. Inspect the valve seating for proper fit.
8. Use a depth gauge to measure the distance "L" between the mounting surface of the cylinder head spring seat and the valve stem end as shown.
Intake "L": 44.7 - 44.9 mm (1.760 - 1.768 inch)
Exhaust "L": 45.4 - 45.6 mm (1.787 - 1.795 inch)
^ If the distance "L", as shown, is shorter than specified, repeat step 5 above to adjust it.
^ If the distance "L", as shown, is longer and the valve stem tip cannot be ground down within the specified limit to obtain the specified distance "L", then replace the valve seat with a new one.
Valve stem tip grinding allowance : 0.2 mm (0.008 inch) or less
VALVE DIMENSIONS
Check the dimensions of each valve.
If the valve head has been worn to less then 0.5 mm (0.020 inch) in margin thickness "T", replace the valve.
VALVE SPRING
Squareness
1. Measure the distance "S" of the valve spring against a right angle as shown.
Out-of-square : less than 2.0 mm (0.079 inch)
2. If the valve spring out-of-square exceeds the limit, replace the valve spring.
Pressure
1. Check the valve spring pressure at the specified compressed height (valve open height).
Standard pressure : 770 - 837 N (78.5 - 85.4 kg, 173.1 - 188.2 lb) at 30.0 mm (1.191 inch) height
Limit pressure: 733 N (74.7 kg, 164.7 lb) at 30.0 mm (1.181 inch) height
2. If not within specification, replace the spring.
ROCKER SHAFT AND ROCKER ARM
1. Check the rocker shafts for scratches, seizure, and wear.
2. Check the outer diameter of the rocker shafts.
Rocker shaft outer diameter : 17.979 - 18.000 mm (0.7078 - 0.7087 inch)
3. Check the inner diameter of the rocker arms.
Rocker arm inner diameter: 18.007 - 18.028 mm (0.7089 - 0.7098 inch)
Rocker arm to shaft clearance: 0.007 - 0.049 mm (0.0003 - 0.0019 inch)
CAUTION: Keep rocker arm with hydraulic valve lifter standing to prevent air from entering hydraulic valve lifter when checking.
HYDRAULIC VALVE LIFTER
1. Check the outer diameter of the valve lifter. Check the contact and sliding surfaces for wear or scratches.
Valve lifter outer diameter : 15.947 - 15.957 mm (0.6278 - 0.6282 inch)
2. Check valve lifter guide inner diameter.
Inner diameter : 16.000 - 16.013 mm (0.6299 - 0.6304 inch)
Standard clearance between valve lifter and lifter guide: 0.043 - 0.066 mm (0.0017 - 0.0026 inch)
Assembly
1. Install the valve component parts.
^ Always use a new valve oil seal.
^ Install the valve spring (uneven pitch type) with the narrow pitch side toward the cylinder head side as shown.
^ After installing the valve component parts, use a plastic hammer to lightly tap the valve stem tip to check for a proper fit.
2. Install the camshafts, locate plates, and cylinder head rear covers.
^ Set the knock pin of the camshafts at the top as shown.
3. Install the valve lifters into the valve lifter guide.
^ Assemble the valve lifters into their original positions and hold all of the valve lifters with a wire to prevent the lifters from falling out of the guide.
^ After installation, remove the wire.
4. Install the rocker shafts with the rocker arms.
^ Tighten the rocker shaft bolts gradually in two or three stages.
^ Before tightening the bolts, set the camshaft with the lobe at the position where lobe is not contacting a lifter.
a. Set the No. 1 piston at TDC on the compression stroke and tighten the rocker shaft bolts for No. 2, No. 4, and No. 6 cylinders.
b. Set the No. 4 piston at TDC on the compression stroke and tighten the rocker shaft bolts for No. 1, No. 3, and No. 5 cylinders.
5. Install the remaining components in the reverse order of removal