Valve Spring
Inspection After DisassemblyCYLINDER HEAD DISTORTION
1. Wipe off oil and remove water scale deposits, old gasket, old sealer, and carbon with a scraper.
CAUTION: Use care not to allow gasket debris to enter passages for oil or water.
2. At each of several locations on bottom surface of cylinder head, measure distortion in six directions.
Standard: 0.1 mm (0.004 inch) or less
VALVE DIMENSIONS
Check dimensions of each valve. Refer to VALVE.
VALVE GUIDE CLEARANCE
Perform this inspection before removing the valve guide.
1. Make sure that the valve stem diameter is within the specification.
2. Push the valve out by approximately 15 mm (0.59 inch) toward the combustion chamber side to measure the valve's run-out volume (in the direction of dial gauge) with dial gauge.
3. Half of the run-out volume accounts for the valve guide clearance.
Valve to guide clearance
Intake: 0.020 - 0.053 mm (0.0008 - 0.0021 inch)
Exhaust: 0.030 - 0.063 mm (0.0012 - 0.0025 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° - 130°C (230° - 266°F) by soaking in heated oil.
2. Drive out valve guide with a press [under a 20 kN (2.2 ton-force) pressure] or hammer and suitable tool.
3. Ream cylinder head valve guide hole.
Valve guide hole diameter for intake and exhaust: 10.175 - 10.196 mm (0.4006 - 0.4014 inch)
4. Heat cylinder head to 110° - 130°C (230° - 266°F) by soaking in heated oil.
5. Press valve guide from camshaft side to dimensions as in illustration.
6. Using valve guide reamer, apply reamer finish to valve guide.
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 seat 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 NG conditions even after the re-check, replace the valve seat.
VALVE SEAT REPLACEMENT
When valve seat is removed, replace with an 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 the cylinder head. Set the machine depth stop to ensure this.
2. Ream cylinder head recess diameter for service valve seat.
Intake: 37.000 - 37.016 mm (1.4567 - 1.4573 inch)
Exhaust: 32.000 - 32.016 mm (1.2598 - 1.2605 inch)
^ Be sure to ream in circles concentric to the valve guide center. This will enable the valve seat to fit correctly.
3. Heat cylinder head to 110° - 130°C (230° - 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 the cold valve seats.
5. Using a valve seat cutter set or a 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 the cutter or cutting many different times may result in a defective valve seat.
Grind to obtain the dimensions indicated as shown.
Standard
D1 dia.: 33.5 mm (1.3189 inch)
D2 dia.: 35.1 - 35.3 mm (1.382 - 1.390 inch)
D3 dia.: 39.0 - 39.2 mm (1.535 - 1.543 inch)
D4 dia.: 28 mm (1.10 inch)
D5 dia.: 29.9 - 30.1 mm (1.177 - 1.185 inch)
D6 dia.: 33.5 - 33.7 mm (1.319 - 1.327 inch)
6. Using compound, grind to adjust valve fitting.
7. Check again for normal contact.
VALVE SPRING SQUARENESS
Set try square along the side of the valve spring and rotate the spring. Measure the maximum clearance between the top face of the spring and the try square.
Limit: 1.9 mm (0.0748 inch)
VALVE SPRING DIMENSIONS AND VALVE SPRING PRESSURE LOAD
Check valve spring pressure with valve spring seat installed at specified spring height. Replace if not within specifications.
CAUTION: Do not remove the valve spring seat.
Part 1:
Part 2:
Valve Spring