Chevrolet Equinox Service Manual: Cylinder Boring and Honing (LAF, LEA, or LUK)

Boring ProcedureMeasure all pistons with a micrometer to determine thecylinder bore diameter. Refer toEngine Block Cleaning and Inspection.Before you use any type of boring bar, use a fine file andclean the top of the cylinder block, removing any dirt or burrs. Ifyou do not check the cylinder block, the boring bar may beimproperly positioned or tilted and the cylinder bore could bebored at an incorrect angle.Carefully follow the instructions furnished by themanufacturer regarding use of the equipment.When you bore the cylinders, ensure all the crankshaftbearing caps are in place. Tighten the crankshaft bearing caps tothe proper torque in order to avoid distortion of the cylinderbores during final assembly.When you take the final cut with a boring bar, leave0.03-mm (0.001-in) on the cylinder borediameter for the finish honing and fit of the piston.Honing Procedure

Note:Fine vertical scratches made by the ring ends do not, bythemselves, cause excessive oil consumption. Do not hone thecylinder in order to remove these scratches.

When honing the cylinders, follow the manufacturer'srecommendations for equipment use, cleaning, and lubrication. Useonly clean, sharp stones of the proper grade for the amount ofmaterial you remove. Dull, dirty stones cut unevenly and generateexcessive heat. Do not hone to final clearance with a coarse ormedium-grade stone. Leave sufficient metal so that allstone marks may be removed with fine-grade stones.Perform final honing with a fine-grade stone, honing thecylinder to the proper clearance.

Note:All measurements of the piston or the cylinder bore should bemade with the components at normal room temperature.

During the honing operation, thoroughly clean the cylinderbore. Repeatedly check the cylinder bore for fit with the selectedpiston.When honing a cylinder for fit to an oversize piston, firstperform the preliminary honing with a 100-gritstone.

Note:A 240-grit stone is preferred for final honing. Ifa 240-grit stone is not available, a 220-gritstone may be used as a substitute.

Perform final cylinder honing with a 240-gritstone and obtain a 45-degree cross hatch pattern.The finish marks should be clean but not sharp. The finishmarks should also be free from imbedded particles and torn orfolded metal.By measuring the selected piston at the sizing point and byadding the average of the clearance specification, you candetermine the final cylinder honing dimension required.After final honing and before the piston is checked for fit,clean the cylinder bores with hot water and detergent. Scrub thebores with a stiff bristle brush and rinse the bores thoroughlywith hot water. Do not allow any abrasive material to remain in thecylinder bores. This abrasive material may cause premature wear ofthe new piston rings and the cylinder bores. Abrasive material willalso contaminate the engine oil and may cause premature wear of thebearings. After washing the cylinder bore, dry the bore with aclean rag.Perform final measurements of the piston and the cylinderbore.Permanently mark the top of the piston for the specificcylinder to which it has been fitted.Apply clean engine oil to each cylinder bore in order toprevent rusting.Deglazing ProcedureIf the bore is glazed but otherwise serviceable, lightlybreak the glaze with a hone. Replace the piston rings. Refer toPiston, Connecting Rod, and Bearing Installation.

Note:A 240-grit stone is preferred for final honing. Ifa 240-grit stone is not available, a 220-gritstone may be used as a substitute.

Using a ball type or self centering honing tool, deglaze thecylinder bore lightly. Deglazing should be done only to remove anydeposits that may have formed. Use a 240-grit stone ofsilicone carbide, or equivalent, material when preforming thedeglazing procedure.The honing stones must be clean, sharp, and straight.Move the hone slowly up and down to produce a45-degree cross-hatch pattern.Clean the bore thoroughly with soap and water.Dry the bore.Rub clean engine oil in the bore.Re-measure the bore.If the cylinder bore is out of specification, the cylinderbore may be oversized to 0.25-mm (0.010-in).There is only one size of oversized pistons and rings available forservice.If honing is not required, clean the cylinder bores with hotwater and detergent. Apply clean engine oil to the bore afterwashing and drying the bore.