Supra Liftback L6-2997cc 3.0L DOHC MFI Twin-Turbo (1997)
Valve Guide: Testing and Inspection
VALVE GUIDE BORE
1. Using a valve guide bushing brush and solvent, clean all the guide bushings.
2. Using a caliper gauge, measure the inside diameter of the guide bushing.
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Bushing inside diameter: 6.010-6.030 mm (0.2366-0.2374 inch).
VALVE GUIDE OIL CLEARANCE
1. Using a micrometer, measure the diameter of the valve stem.
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Valve stem diameter:
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Intake: 5.970-5.985 mm (0.2350-0.2356 inch).
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Exhaust: 5.965-5.980 mm (0.2348-0.2354 inch).
2. Subtract the valve stem diameter measurement from the guide bushing inside diameter measurement.
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Standard oil clearance:
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Intake: 0.025-0.060 mm (0.0010-0.0024 inch).
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Exhaust: 0.030-0.065 mm (0.0012-0.0026 inch).
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Maximum oil clearance:
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Intake: 0.08 mm (0.0031 inch).
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Exhaust: 0.10 mm (0.0039 inch).
3. If the clearance is greater than maximum, replace the valve and/or guide bushing.
