Refinishing Cylinder Walls

Honing is recommended for refinishing cylinder walls only when no cross-hatch pattern is visible on cylinder walls or for fitting pistons (6108) to the specified clearance. The grade of hone is determined by the amount of metal to be removed. Follow the instructions of the hone manufacturer. If coarse stones are used to start the honing operation, leave enough material so that all hone marks can be removed with the finishing hone which is used to obtain the proper piston clearance. After honing, thoroughly clean cylinder bores with a detergent and water solution.

NOTE:
^ Only experienced technicians should perform this work.
^ Before any cylinder is refinished, all main bearing caps must be in place and tightened to the proper torque so that the crankshaft bearing bores will not become distorted from the refinishing operation.

Cylinder walls that are severely marred and/or worn beyond the specified limits should be refinished. Hone only the cylinder or cylinders that require refinishing. All pistons are the same weight, both standard and oversize; therefore, various sizes of pistons can be used without upsetting engine balance. Refinish the cylinder with the most wear first to determine the maximum oversize. If the cylinder will not clean up when refinished for the maximum oversize piston recommended, replace the cylinder blocks.

Refinish the cylinder to within approximately 0.038 mm (0.0015 inch) of the required oversize diameter. This will allow enough stock for the final step of honing to obtain the correct surface finish and pattern. For the proper use of the refinishing equipment, follow the manufacturer's instructions.

Use a motor-driven, spring pressure-type Engine Cylinder Hone Set T73L-6011-A and hone at a speed of 300-500 rpm. Hones of grit sizes 180-220 will normally provide the desired bore surface finish of 18-38 AA.

CAUTION: After the final operation in either of the two refinishing methods described and prior to checking the piston fit, thoroughly clean with a detergent and water solution and then oil the cylinder walls or rusting of cylinder bores may occur.

When honing the cylinder bores, use a lubricant mixture of equal parts of kerosene and clean engine oil meeting specification WSS-M2C153-F. Operate the hone to produce a cross-hatch finish on the cylinder bore. The cross-hatch pattern should be at an angle of approximately 30 degrees to the cylinder bore. Mark the pistons to correspond to the appropriate cylinders. When the refinishing of all affected cylinders has been completed and all pistons are fitted, thoroughly clean the entire cylinder blocks and oil the cylinder walls.





Refinish cylinders that are deeply scored, out-of-round, and/or taper exceeds specification. If the cylinder walls have minor surface imperfections, but the out-of-round and taper are within limits, try to remove the imperfections by honing the cylinder walls and installing new service piston rings, providing the piston clearance is within specification.