Piston: Testing and Inspection

1. Using a gasket scraper, remove the carbon from the piston top.






2. Using a groove cleaning tool or broken ring, clean the piston ring grooves.






3. Using solvent and a brush, thoroughly clean the piston.

NOTE: Do not use a wire brush.

4. Inspect piston oil clearance as follows:

NOTE:
- There are three sizes of the standard piston diameter, marked "1", "2" and "3" accordingly. The mark is stamped on the piston top.
- The shape of the piston varies for the RH and LH banks. The RH piston is marked with "R", the LH piston with "L"
- Ensure piston and bore have the same number mark.






(a) Using a micrometer, measure the piston diameter at right angles to the piston pin center line, 26 mm (1.02 in) from the piston head.
Piston diameter:
Pistons with mark "1": 87.410-87.420 mm (3.4413-3.4417 in).
Pistons with mark "2": 87.420-86.430 mm (3.4417-3.4421 in).
Pistons with mark "3": 87.430-87.440 mm (3.4421-3.4425 in).






5. Using a suitable cylinder gauge, measure the cylinder bore diameter at positions A, B and C in the thrust direction.
6.






6. Subtract the piston diameter measurement from the cylinder bore diameter measurement to determine oil clearance.
Standard oil clearance: 0.080-0.100 mm (0.0031-0.0039 in).
Maximum oil clearance:v0.120 mm (0.0047 in).
If the oil clearance is greater than maximum, replace all the eight pistons. If necessary, replace the cylinder block.






7. Using a suitable feeler gauge, measure the clearance between new piston ring and the wall of the ring groove.
Ring groove clearance: No.1 and No.2: 0.020-0.060 mm (0.0008-0.0024 in).
If the clearance is not as specified, replace the piston.
8. Inspect piston ring end gap as follows:
(a) Insert the piston ring into the cylinder bore.






(b) Using a piston, push the piston ring a little beyond the bottom of the ring travel, 105.000 mm (4.1300 in) from the top of the cylinder block.






(c) Using a suitable feeler gauge, measure the end gap as shown.
Standard end gap:
No.1: 0.250-0.450 mm (0.0098- 0.0177 in).
No.2: 0.350-0.500 mm (0.0138-0.0197 in).
Oil (Side rail): 0.150-0.550 mm (0.0059-0.0217 in).
Maximum end gap:
No.1: 1.050 mm (0.0413 in).
No.2: 1.100 mm (0.0433 in).
Oil (Side rail): 1.150 mm (0.0453 in).
9. If the end gap is greater than maximum, replace the piston ring.
10. If the end gap is greater than maximum, even with a new piston ring, replace the cylinder block.






11. Inspect piston pin fit, at 60°C (140°F), you should be able to push the piston pin into the piston pin hole with your thumb.