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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Engine Mechanical - 8.1L) >> Repair Instructions >> Off-Vehicle Repair Instructions >> Cylinder Head Cleaning and Inspection >> Valve Guide Measurement Procedure

Valve Guide Measurement Procedure

WARNING: This page is about a different variant/trim than selected.
    Fig 1: Measuring Valve Stem-To-Guide Clearance
    GM677797Courtesy of GENERAL MOTORS CORP.
    IMPORTANT: Excessive valve stem-to-guide clearance may cause an excessive oil consumption and may also cause a valve to break. Insufficient clearance will result in noisy and sticky functioning of the valve and will disturb the engine assembly smoothness.
  1. Measure the valve stem-to-guide clearance.
    1. Clamp the J 8001  on the exhaust port side of the cylinder head.
      2. IMPORTANT: The indicator stem must contract the side of the valve stem just above the valve guide.
    2. Locate the indicator so that the movement of the valve stem from side to side, crosswise to the cylinder head, will cause a direct movement of the indicator stem.
    3. Drop the valve head about 1.6 mm (0.064 in) off the valve seat.
    4. Use light pressure when moving the valve stem from side to side in order to obtain a clearance reading. Refer to Engine Mechanical Specifications .
    2. Fig 2: View Of Valve Guide W/Excessive Clearance
    GM719136Courtesy of GENERAL MOTORS CORP.
  2. Valve guide (2) with excessive clearance must be repaired. Refer to Valve Guide Reaming/Valve and Seat Grinding .
  3. Replace the cylinder head if the valve guide cannot be repaired or reamed to accept an oversize valve stem.
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