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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1021 (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 car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
    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 1: Measuring Valve Stem-To-Guide Clearance
    GM677797Courtesy of GENERAL MOTORS CORP.
  2. Valve guide (2) with excessive clearance must be repaired. Refer to Valve Guide Reaming/Valve and Seat Grinding .
    3. Fig 2: View Of Valve Guide W/Excessive Clearance
    GM719136Courtesy of GENERAL MOTORS CORP.
  3. Replace the cylinder head if the valve guide cannot be repaired or reamed to accept an oversize valve stem.
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