Piston - Measuring Cylinder Clearance Update
Bulletin: P92-024Section: Product
Date: 12/7/92
Model: Range Rover
Defender
Applicable to: USA/Canada
SUBJECT:
Piston Measuring - Update
Please use the following information and procedures when calculating piston to cylinder clearance.
^ Pistons must be measured at the points shown by the arrows on the diagram below. Make sure that the micrometer is placed exactly 90° to the piston pin bore.
^ Always calibrate your bore gauge with the same micrometer used to measure the pistons.
^ The micrometer, bore gauge, pistons and engine block must be at the same temperature for accuracy. Room temperature of approximately 70°F (21°C) preferred.
^ Refer to Service Bulletin P91-003 for piston/bore specifications. Since 4.2 and 3.9 engines share a common 94mm (nominal) bore, use 3.9 bore specs for the 4.2.
^ Refer to the Workshop Manual, Section 12, Page 17 for bore measuring procedures.