1998 Lexus SC 300FACTORY OEM SERVICE PROCEDURE

Valve Clearance: SC400

NOTE: Check and adjust valves with engine cold.
  1. Remove engine cover. Remove air cleaner and intake air connector assembly. Remove bolts and No. 3 timing belt cover (upper cover with gasket). Remove ignition coils.
  2. Remove bolts, seal washers and right valve cover. Remove transmission oil dipstick. Disconnect PCV hose. Disconnect engine wire clamp from delivery pipe wire bracket. Remove bolts, seal washers and left valve cover.
  3. Rotate crankshaft clockwise until piston No. 1 is at TDC of compression stroke. Ensure groove on crankshaft pulley aligns with "0" timing mark on timing belt cover. Timing marks on camshaft pulleys should align with timing marks on timing belt cover No. 4 (upper inner cover). See Figure. If timing marks do not align rotate crankshaft clockwise 360 degrees.
  4. Measure and record clearance of intake valves for cylinders No. 1, 2, 5, 7 and 8, and exhaust valves for cylinders No. 1, 4 and 8. See Figure. Rotate crankshaft 360 degrees. Measure and record clearance of intake valves for cylinders No. 3, 4 and 6, and exhaust valves for cylinders No. 2, 3, 5, 6 and 7.
  5. Compare measured clearance with specified clearance. See VALVE CLEARANCE SPECIFICATIONS TABLE (SC400) . If clearance is within specification, go to step 8). If clearance is not within specification, rotate crankshaft until camshaft lobe of valve to be adjusted is facing upward, away from shim.
    VALVE CLEARANCE SPECIFICATIONS

    Application In. (mm)
    Intake .006-.010 (.15-.25)
    Exhaust .010-.014 (.25-.36)
  6. Remove timing belt from camshaft timing pulleys. See appropriate article in the ENGINES section. Remove camshafts for appropriate bank and valve. See appropriate article in the ENGINES section.
  7. Remove valve lifter and adjusting shim. Ensure not to drop adjusting shim into lifter line when removing valve lifter. Select a shim of appropriate thickness. See SELECTING SHIMS  under VALVE CLEARANCE. Recheck valve clearance after shim is installed.
  8. To complete installation, reverse removal procedure. Remove old valve cover seal packing material. Install NEW Seal Packing (08826-00080) material. See Figure. Use NEW gaskets as necessary. Tighten nuts and bolts to specification. See TORQUE SPECIFICATIONS .
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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