GM Service Manual Online
For 1990-2009 cars only

Tools Required

SA9171E Flex Hone


    Object Number: 877260  Size: SH
  1. Cylinder wall SA9171E should be used for deglazing whenever pistons or ring sets require replacement and cylinder bores are found within specifications. Refer to step 7 for finish honing procedures.
  2. If one or more cylinder bores are damaged or exceed out of round specifications, cylinder honing and/or boring will be required. It is good practice to obtain the pistons before re-working a cylinder bore.
  3. Select oversize piston.

    Oversize Piston Diameters Available:

    0.125 mm (0.005 in)

    0.4 mm (0.0157 in)


    Object Number: 873502  Size: SH

    Important: The cylinder bore diameter is determined by measuring at 2 axis, transverse and longitudinal 63.5 mm (2 1/2 in) from top of block and averaging them together.

  4. Calculate amount to hone or bore cylinder.
  5. • Using a micrometer, measure the piston diameter at a right angle to the piston pin hole center line, 5 mm (0.2 in) from the bottom of the piston.
    • Calculate the amount each cylinder is to be honed or bored as follows:
    • Size to be honed or bored = P + C - H, where P = piston diameter, C = piston clearance 0.006 mm (0.0002 in) to 0.044 mm ( 0.0017 in), and H = allowance for finish honing 0.05 mm (0.002 in).

    Object Number: 880332  Size: SH

    Important:  Cylinders 1 and 4 are 0.01 mm (0.0004 in) larger than 2 and 3.

  6. Bore or finish hone cylinders to the following calculated dimensions:
  7. • Piston/Bore O.S. Dimension: 0.125 mm (0.005 in)
    • Bore O.S. Dimension: 82.115-82.135 mm (Cylinder No. 2 and 3) (3.2328-3.2336 in) (Cylinder No. 1 and 4) 82.125-82.145 mm (3.2333-3.2340 in)
    • Piston O.S. Dimension: 82.091-82.109 mm (3.239-3.2326 in)

    Object Number: 877273  Size: SH

    Important: 0.125 mm (0.005 in) oversize bores can be honed to size following steps 6 and 7 under honing.

  8. Piston/Bore O.S. Dimension: 0.4 mm (0.016 in)
  9. Bore O.S. Dimension: 82.39-82.41 mm (Cylinder No. 2, 3) (3.2436-3.2444 in) (Cylinder No. 1, 4) 82.40-82.42 mm (3.2440-3.2448 in)

    Piston O.S. Dimension: 82.381-82.399 mm (3.2440-3.2448 in)


    Object Number: 877252  Size: SH

    Important: The cylinder bore, piston and ring set must be equivalent in oversize dimensions (0.125 mm or 0.400 mm O.S.).

    Important: 0.4 mm (0.016 in) oversize bores require boring prior to honing.

  10. Follow the manufacturer's instructions and machine the cylinder bore to 0.038-0.062 mm  (0.0015-0.0025 in) less than the required finished dimension to allow for honing.
  11. Caution: Do not allow hone to come out of the cylinder bore while it is turning. The stones could be released and cause injury.

  12. Hone bores to within 0.005 mm (0.0002 in) of desired size using 120-150 grit stones.
  13. Finish hone to desired size by removing 0.005 mm (0.0002 in) left in second step using 320 grit stones.

  14. Object Number: 871167  Size: SH

            Important: Make sure crankshaft pulley/damper keyway is at 3 or 9 o'clock position to prevent damage of crankshaft connecting rod journals during honing.

    8.1. Hone the cylinder bore using a 10W-30 or 5W-30 weight motor oil and flex hone SA9171E .
    8.2. Make sure the flex hone is rotating upon entry and removal from cylinder bore.

            Important: The recommended speed of the flex hone is 150-200 RPM. Do not use air pressure driven or high-speed tools.

    8.3. Use 60 strokes per minute. Honing time should be approximately 20 seconds or 20 strokes per cylinder to develop a 45-50° (included angle) honing cross-hatch. One STROKE consists of a full downward and upward motion of the flex hone in the cylinder bore.
    8.4. Thoroughly scrub cylinder bores after honing with a scrub brush, a strong solution of hot water and Tide® powder laundry detergent, or equivalent. Thoroughly rinse with hot clean water (high-pressure, if available).

            Important: If the cylinder bores are not thoroughly cleaned, the residual grit from the honing stones will wear out the piston rings and cylinder bores extremely fast, resulting in oil consumption. Never use solvent to clean cylinder bores; it will only redistribute the grit on the cylinder walls; detergent and hot water will carry the grit away.

    8.5. Dry the cylinder bores and wipe them with a clean white towel saturated with engine oil. Dark residual grit on the towel after wiping the cylinder bore indicates the bores are not clean. The cleaning process in step 7.4 must be repeated until the towel is free of all dark residual grit.