Measuring Cylinder Bore Out-of-Round
Courtesy of GENERAL MOTORS COMPANY
- Measure both the thrust and non-thrust cylinder diameter at 10 mm (0.394 in) below the deck surface (1). Record your measurements.
- Calculate the difference between the 2 measurements. The result will indicate out-of-round at the upper end of the cylinder.
- Measure both the thrust and non-thrust cylinder diameter at 125 mm (4.921 in) below the deck surface (2). Record your measurements.
- Calculate the difference between the 2 measurements. The result will indicate out-of-round at the lower end of the cylinder.
- Compare your results with the Engine Mechanical Specifications (LTG)
. If the cylinders exceed these specifications, replace the engine block.