1. Inspect the pistons for the following conditions:

•	Eroded areas at the top of the piston (1)

•	Ring grooves for nicks, burrs that may cause binding (2)

•	Warped or worn ring lands (2)

•	Scuffed or damaged skirt coating (3)

•	Cracked ring lands, skirts or pin bosses (4)

•	Worn piston pin bores or worn piston pins (5)

•	Piston pin retainer grooves for burrs (6)

2. Replace pistons that show any signs of damage or excessive wear.

1. Using an outside micrometer, measure the width of the piston 40 mm (1.575 in) below the crown (top) of the piston at the thrust surface which is perpendicular to the centerline of the piston pin (1).
2. Compare the measurement to the diameter listed in the Engine Mechanical Specifications .
3. You must replace the piston if any of its dimensions are out of specification. There are no oversized pistons available.

1. Piston pin bores and pins must be free of varnish or scuffing.
2. Use an outside micrometer to measure the piston pin in the piston contact areas.



3. Using an inside micrometer, measure the piston pin bore.
4. Subtract the measurement of the piston pin bore from the piston pin.
5. Compare the result with the Engine Mechanical Specifications .
6. If the clearance is excessive, determine which piece is out of specification and replace as necessary.

1. Place the piston ring in the area of the bore where the piston ring will travel, approximately 25 mm (1 in) down from the deck surface. Be sure the ring is square with the cylinder bore by positioning the ring with the piston head.
2. Measure the end gap of the piston ring with feeler gages. Compare the measurements with those provided in the Engine Mechanical Specifications .
3. If the clearance exceeds the provided specifications, the piston rings must be replaced.
4. Repeat this procedure for all the piston rings.

1. Roll the piston ring entirely around the piston ring groove. If any binding is caused by the ring groove, dress the groove with a fine file. If any binding is caused by a distorted piston ring, replace the ring.
2. With the piston ring on the piston, use feeler gages to check side clearance at multiple locations.
3. Compare your measurements with those found in the Engine Mechanical Specifications .
4. If the clearance is greater than specifications, replace the piston rings.
5. If new piston rings do not bring the clearance within the specification, the piston must be replaced.

1. Clean the connecting rods in solvent.

Caution: Refer to Safety Glasses Caution in the Preface section.

2. Dry the connecting rod using compressed air.
3. Remove the connecting rod cap and clean the threads.
4. Remove the connecting rod bearing and discard. Never reuse a connecting rod bearing used in a running engine.

1. Inspect the piston pin bushing (4) for scoring or damage.
2. Inspect the connecting rod beam (1) for twisting or bending.
3. Inspect the rod cap (2) for any nicks or damage caused by possible interference.
4. Inspect for scratches or abrasion on the rod bearing seating surface.

Important: DO NOT scrape the rod or rod cap.

5. If the connecting rod bores contain minor scratches or abrasions, clean the bores in a circular direction with a light emery paper.

Piston Pin End

Important: Measurements of all components should be taken with the components at normal room temperature.

1. Using an outside micrometer, take 2 measurements of the piston pin in the area of the connecting rod contact.



2. Using an inside micrometer, measure the connecting rod piston pin bore.
3. Subtract the piston pin diameter from the piston pin bore.
4. Compare the clearance measurements with the Engine Mechanical Specifications .
5. If the clearance is excessive, replace the piston pin. If a new pin does not resolve the clearance problem, replace the connecting rod.

Connecting Rod Crankshaft Bearing End

Important: Measurements of all components should be taken with the components at normal room temperature.

1. Using an inside micrometer, measure the connecting rod crankshaft bearing bore.
2. Compare the bore measurements with the Engine Mechanical Specifications .
3. Replace the connecting rod if the bore is out of specifications. DO NOT recondition the connecting rod.