Piston And Connecting Rod Measurement Procedure
Piston Pin To Connecting Rod Bore And Piston Bore Clearance
- Measure the clearance between the piston pin and the connecting rod bore. Use the following procedure:
- Measure the piston pin outside diameter.
- Measure the connecting rod bore diameter.
- Substract the piston pin outside diameter from the connecting rod diameter to calculate the clearance. Engine Mechanical Specifications
- If there is excessive clearance, replace the piston pin.
- If there is still excessive clearance, replace the connecting rod.
- Measure the clearance between the piston pin and the piston bore. Use the following procedure:
- Measure the piston pin outside diameter.
- Measure the piston bore diameter.
- Substract the piston pin outside diameter from the piston bore diameter to calculate the clearance. Engine Mechanical Specifications
- If there is excessive clearance, replace the piston pin.
- If there is still excessive clearance, replace the piston.
Piston Ring Clearance
Install the piston rings to the cylinder and measure the piston ring end gap (1). Compare the measurements with those provided below:
- The upper compression ring end gap (1). Place the piston ring in the area of the bore where the piston ring will travel approximately 10 mm (0.4 in) down from the deck surface. Engine Mechanical Specifications
- The lower compression ring end gap (1). Place the piston ring in the area of the bore where the piston ring will travel approximately 18 mm (0.7 in) down from the deck surface. Engine Mechanical Specifications
- The oil scraper ring end gap (1). Place the piston ring in the area of the bore where the piston ring will travel approximately 23 mm (0.9 in) down from the deck surface. Engine Mechanical Specifications
- If the clearance is greater than the provided specifications, the piston rings must be replaced.
Measure the piston ring axial clearance (1). Compare the measurements with those provided below:
- The upper compression ring end gap. Engine Mechanical Specifications
- The lower compression ring end gap. Engine Mechanical Specifications
- The oil scraper ring end gap. Engine Mechanical Specifications
- If the clearance is greater than the provided specifications, replace the piston rings.
- If the clearance is still to great, replace the pistons.
Piston to Engine Block Cylinder Bore Clearance
- Measure the engine cylinder bore. Engine Block Overhaul
Measure the width of the piston (1) at 30 mm (1.181 in) below the crown, top, at the thrust surfaces of the piston, perpendicular to the piston pin centerline.
- Subtract the piston diameter from the cylinder bore diameter in order to calculate the piston-to-bore clearance. Engine Mechanical Specifications
- If the clearance obtained through measurement is greater than these specifications and the cylinder bores are within the specification, replace the piston.
Connecting Rod Bearing Clearance (with Micrometer Gauge Internal Measuring Device)
- Install the connecting bearings and the connecting rod bearing caps.
- Tighten the connecting rod bearing cap bolts in the following sequence with EN-45059 Angle Meter. Fastener Specifications
Measure the connecting rod bearing diameters at 3 points (1). Use an internal measuring device.
- Calculate the average connecting rod inner diameter.
Formula: (1. result + 2. result + 3. result) / 3
Measure the connecting rod journal diameter at 2 points between (1) and (3) and between (2) and (4). Use a micrometer gauge.
- Calculate the average connecting rod journal diameter.
Formula: (1. result + 2. result) / 2.
- Subtract the average connecting rod journal diameter from the average connecting rod bearing diameter in order to determine the connecting rod bearing clearance. Engine Mechanical Specifications
Refer to Fastener Caution .
Refer to Torque-to-Yield Fastener Caution .