Disassembly and Assembly
CYLINDER HEAD
Disassembly and Assembly
DISASSEMBLY
1. Remove spark plug with spark plug wrench (commercial service tool).
2. Remove valve lifter.
^ Mark position on valve lifter for assembly.
3. Remove valve collet.
^ Compress valve spring with valve spring compressor, attachment and adapter (SST).
4. Remove valve collet with magnet hand.
CAUTION: When working, take care not to damage valve lifter holes.
4. Remove valve spring retainer and valve spring.
5. Push valve stem to combustion chamber side, and remove valve.
^ Inspect valve guide clearance before removal.
^ Mark position on valve for assembly.
6. Remove valve oil seals using valve oil seal puller (SST).
7. Remove valve spring seat.
8. If valve seat must be replaced, refer to "VALVE SEAT CONTACT".
9. If valve guide must be replaced, refer to "VALVE GUIDE CLEARANCE".
10. Remove spark plug tube, as necessary.
^ Using a pair of pliers, pull spark plug tube out of cylinder head.
CAUTION:
^ Take care not to damage cylinder head.
^ Once removed, a spark plug tube will be deformed and cannot be reused. Do not remove it unless absolutely necessary.
Inspection After Disassembly
CYLINDER HEAD DISTORTION
^ At each of several locations on bottom surface of cylinder head, measure distortion in six directions.
Limit: 0.1 mm (0.004 inch)
^ If it exceeds the limit, replace the cylinder head.
VALVE DIMENSIONS
Check dimensions of each valve.
VALVE GUIDE CLEARANCE
^ Perform this inspection before removing valve guide.
^ Make sure that the valve stem diameter is within the specification.
^ Push the valve out by approximately 25 mm (0.98 inch) toward the combustion chamber side to measure the valve's run-out volume (in the direction of dial gauge) with dial gauge.
^ The half of the run-out volume accounts for the valve guide clearance.
^ On the another way, measure valve stem diameter and valve guide inner diameter to calculate the clearance.
Valve guide clearance:
Standard
Intake: 0.020 - 0.053 mm (0.0008 - 0.0021 inch)
Exhaust: 0.030 - 0.063 mm (0.0012 - 0.0025 inch)
Limit
Intake: 0.08 mm (0.0031 inch)
Exhaust: 0.09 mm (0.0035 inch)
VALVE GUIDE REPLACEMENT
When valve guide is removed, replace with oversized (0.2 mm, 0.008 inch) valve guide.
1. To remove valve guide, heat cylinder head to 110 to 130°C (230 to 266°F) by soaking in heated oil.
2. Drive out valve guide with a press [under a 20 kN (2 ton, 2.2 US ton, 2.0 Imp ton) pressure] or hammer and suitable tool.
CAUTION: Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.
3. Using valve guide reamer, ream cylinder head valve guide hole.
Valve guide hole diameter (for service parts):
Intake and exhaust: 10.175 - 10.196 mm (0.4006 - 0.4014 inch)
4. Heat cylinder head to 110 to 130°C (230 to 266°F) by soaking in heated oil.
5. Press valve guide from camshaft side to dimensions as in illustration.
Projection "L"
Intake and exhaust: 12.6 - 12.8 mm (0.496 - 0.504 inch)
CAUTION: Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.
6. Using valve guide reamer, apply reamer finish to valve guide.
Standard:
Intake and exhaust: 6.000 - 6.018 mm (0.2362 - 0.2369 inch)
VALVE SEAT CONTACT
^ After confirming that the dimensions of valve guides and valves are within specifications, perform this procedure.
^ Apply prussian blue (or white lead) onto contacting surface of valve seat to check the condition of the valve contact on the surface.
^ Check if the contact area band is continuous all around the circumference.
^ If not, grind to adjust valve fitting and check again. If the contacting surface still has NO conditions even after the re-check, replace valve seat.
VALVE SEAT REPLACEMENT
When valve seat is removed, replace with oversized (0.5 mm, 0.020 inch) valve seat.
1. Bore out old seat until it collapses. Boring should not continue beyond the bottom face of the seat recess in cylinder head. Set the machine depth stop to ensure this.
2. Ream cylinder head recess diameter for service valve seat.
Oversize [0.5 mm (0.020 inch)]
Intake: 38.500 - 38.516 mm (1.5157 - 1.5164 inch)
Exhaust: 32.700 - 32.716 mm (1.2874 - 1.2880 inch)
^ Be sure to ream in circles concentric to the valve guide center. This will enable valve to fit correctly.
3. Heat cylinder head to 110 to 130°C (230 to 266°F) by soaking in heated oil.
4. Provide valve seats cooled well with dry ice. Force fit valve seat into cylinder head.
CAUTION:
^ Avoid directly touching cold valve seats.
^ Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.
5. Using valve seat cutter set (commercial service tool) or valve seat grinder, finish the seat to the specified dimensions.
CAUTION: When using valve seat cutter, firmly grip the cutter handle with both hands. Then, press on the contacting surface all around the circumference to cut in a single drive. Improper pressure on with the cutter or cutting many different times may result in stage valve seat.
Grind to obtain the dimensions indicated.
Standard:
D1 diameter: 35 mm (1.38 inch)*1
D2 diameter: 36.6- 36.8 mm (1.441 - 1.449 inch)*2
D3 diameter: 28.7 mm (1.130 inch)*'
D4 diameter: 30.6 - 30.8 mm (1.205 - 1.213 inch)*2
*1: Diameter made by crossing of conic angles 60° and 90°
*2: Diameter made by crossing of conic angles 90° and 120°
6. Using compound, grind to adjust valve fitting.
7. Check for normal contact again.
VALVE SPRING SQUARENESS
^ Set try square along the side of valve spring and rotate the spring. Measure the maximum clearance between the top face of spring and try square.
Limit: 2.0 mm (0.079 inch)
^ If it exceeds the limit, replace the valve spring.
VALVE SPRING DIMENSIONS AND VALVE SPRING PRESSURE LOAD
Check valve spring pressure at specified spring height. Standard:
Intake and exhaust
Free height: 45.62 mm (1.7961 inch)
Installation height: 37.00 mm (1.4567 inch)
Installation load: 184 - 208 N (18.8 - 21.2 kg, 41.4 - 46.8 lbs.)
Height during valve open: 27.80 mm (1.0945 inch)
Load with valve open: 407 - 459 N (41.5 - 46.8 kg, 91.5 - 103.2 lbs.)
ASSEMBLY
1. When valve guide is removed, install it.
2. When valve seat is removed, install it.
3. Install valve oil seals.
^ Install with valve oil seal drift (SST) to match dimension in illustration.
Height "H" (Without valve spring seat installed)
Intake and exhaust: 14.3 - 14.9 mm (0.563 - 0.587 inch)
4. Install valve spring seat.
5. Install the valves.
^ Larger diameter valves are for intake side.
6. Install valve spring (uneven pitch type).
^ Install smaller pitch end (paint mark) to cylinder head side (valve spring seat side).
7. Install valve spring retainer.
8. Install valve collet.
^ Compress valve spring with valve spring compressor, attachment and adapter (SST). Install valve collet with magnet hand.
CAUTION: When working, take care not to damage valve lifter holes.
^ Tap valve stem edge lightly with plastic hammer after installation to check its installed condition.
9. Install valve lifter.
10. Install spark plug tube.
^ Press-fit spark plug tube following procedure below.
a. Remove old liquid gasket adhering to cylinder-head mounting hole.
b. Apply liquid gasket to area within approximately 12 mm (0.47 inch) from edge of spark plug tube press-fit side.
Use Genuine RTV Silicone Sealant or equivalent.
c. Using a drift, press-fit spark plug tube so that its height "H" is as specified in the figure.
Standard press-fit height "H": 38.55 mm (1.5177 - 1.5217 inch)
CAUTION:
^ When press-fitting, take care not to deform spark plug tube.
^ After press-fitting, wipe off liquid gasket protruding onto cylinder-head upper face.
11. Install spark plug.