Valve Spring

Inspection After Disassembly

CYLINDER 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.
Limit 0.1 mm (0.004 inch) or less

VALVE DIMENSIONS





Check dimensions of each 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 valves runout volume (in the direction of dial gauge) with dial gauge.





3. Half of the run-out volume accounts for the valve guide clearance.
Intake valve clearance 0.020 - 0.053 mm (0.0008 - 0.0021 inch) or less
Exhaust valve clearance 0.030 - 0.063 mm (0.0012 - 0.0025 inch) or less

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 (2.2 ton-force) pressure] or hammer and suitable tool.





3. Ream cylinder head valve guide hole using suitable reamer.
Intake and exhaust valve guide hole diameter (Service) 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 shown.





6. Apply finish to valve guide using suitable reamer.
Intake and exhaust 6.000 - 6.018 mm (0.2362 - 0.2369 inch)

VALVE SEAT CONTACT





NOTE: 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 NO conditions even after the re-check, replace the valve seat.

VALVE SEAT REPLACEMENT

NOTE: 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° to 130°C (230° to 266°F) by soaking in heated oil.
4. Use valve seats cooled well with dry ice. Force fit valve seat into cylinder head.

CAUTION: Avoid directly touching the cold valve seats.





5. Finish the seat to the specified dimensions using suitable tool.

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.








Valve Spring