Piston, Pin, Connecting Rod
Piston, Pin, and Connecting Rod ReplacementDisassembly
1. Remove the piston from the cylinder block.
2. Apply engine oil to the piston pin snap rings (A), and turn them in the ring grooves until the end gaps are lined up with the cutouts in the piston pin bores (B).
NOTE: Take care not to damage the ring grooves.
3. Remove both snap rings (A). Start at the cutout in the piston pin bore. Remove the snap rings carefully so they do not go flying or get lost. Wear eye protection.
4. Heat the piston and connecting rod assembly to approximately 158°F (70°C), then remove the piston pin.
Inspection
NOTE: Inspect the piston, piston pin, and connecting rod when they are at room temperature.
1. Measure the diameter of the piston pin.
Piston Pin Diameter:
Standard (New): 21.961 - 21.965 mm (0.8646 - 0.8648 inch)
Service Limit: 21.953 mm (0.8643 inch)
2. Zero the dial indicator to the piston pin diameter.
3. Check the difference between the piston pin diameter and piston pin hole diameter in the piston.
Piston Pin-to-Piston Clearance:
Standard (New): -0.005 to +0.002 mm (-0.00020 to +0.00008 inch)
Service Limit: 0.005 mm (0.0002 inch)
4. Measure the piston pin-to-connecting rod clearance.
Piston Pin-to-Connecting Rod Clearance:
Standard (New): 0.005 - 0.015 mm (0.0002 - 0.0006 inch)
Service Limit: 0.02 mm (0.0008 inch)
Reassembly
1. Install a piston pin snap ring (A).
2. Coat the piston pin bore in the piston, the bore in the connecting rod, and the piston pin with engine oil.
3. Heat the piston to approximately 158°F (70°C).
4. Install the piston pin (A). Assemble the piston (B) and connecting rod (C) with the arrow (D) and the embossed mark (E) on the same side.
5. Install the remaining snap ring (F).
6. Turn the snap rings in the ring grooves until the end gaps are positioned at the bottom of the piston.
Piston Ring Replacement
1. Remove the piston from the cylinder block.
2. Using a ring expander (A), remove the old piston rings (B).
3. Clean all ring grooves thoroughly with a squared off broken ring or ring groove cleaner with a blade to fit the piston grooves.
The top and 2nd ring grooves are 1.2 mm (0.05 inch) wide. The oil ring groove is 2.0 mm (0.08 inch) wide. File down a blade if necessary.
Do not use a wire brush to clean the ring grooves, or cut the ring grooves deeper with the cleaning tools.
NOTE: If the piston is to be separated from the connecting rod, do not install new rings yet.
4. Using a piston, push a new ring (A) into the cylinder bore 15 - 20 mm (0.6 - 0.8 inch) from the bottom.
5. Measure the piston ring end-gap (B) with a feeler gauge:
^ If the gap is too small, check to see if you have the proper rings for your engine.
^ If the gap is too large, recheck the cylinder bore diameter against the wear limits. If the bore is over the service limit, the cylinder block must be rebored.
Piston Ring End-Gap:
Top Ring
Standard (New): 0.20-0.35 mm (0.008 - 0.014 inch)
Service Limit: 0.60 mm (0.024 inch)
Second Ring
K20A3 engine
Standard (New): 0.40 - 0.55 mm (0.016 - 0.022 inch)
Service Limit: 0.70 mm (0.028 inch)
K20A2 engine
Standard (New): 0.50 - 0.65 mm (0.020 - 0.026 inch)
Service Limit: 0.75 mm (0.030 inch)
Oil Ring
K20A3 engine
Standard (New): 0.25 - 0.65 mm (0.010 - 0.026 inch)
Service Limit: 0.75 mm (0.030 inch)
K20A2 engine
Standard (New): 0.20 - 0.70 mm (0.008 - 0.028 inch)
Service Limit: 0.80 mm (0.031 inch)
6. Install the top ring and second ring as shown. The top ring (A) has a T1 or R1 mark and the second ring (B) has a T2 or R2 mark. The manufacturing marks (C) must be facing upward.
7. Rotate the rings in their grooves to make sure they do not bind.
8. Position the ring end gaps as shown:
9. After installing a new set of rings, measure the ring-to-groove clearances:
Top Ring Clearance
K20A3 engine
Standard (New): 0.035 - 0.060 mm (0.0014 - 0.0024 inch)
Service Limit: 0.13 mm (0.005 inch)
K20A2 engine
Standard (New): 0.040 - 0.065 mm (0.0016 - 0.0026 inch)
Service Limit: 0.13 mm (0.005 inch)
Second Ring Clearance
K20A3 engine
Standard (New): 0.030 - 0.055 mm (0.0012 - 0.0022 inch)
Service Limit: 0.13 mm (0.005 inch)
K20A2 engine
Standard (New): 0.045 - 0.070 mm (0.0018 - 0.0028 inch)
Service Limit: 0.13 mm (0.005 inch)