Piston And Piston Rings
- Clean the piston.
- Using a gasket scraper, remove the carbon from the piston top.
- Using a groove cleaning tool or broken ring, clean the piston ring grooves.
- Using solvent and a brush, thoroughly clean the piston.NOTE: Do not use a wire brush.
- The standard measurement of the piston outside diameter is taken 39.15mm (1.5413in) from top land of the piston.
Standard diameter:
76.47~76.50mm (3.0106~3.0118in)
- Calculate the difference between the cylinder bore inner diameter and the piston outer diameter.
Piston-to-cylinder clearance:
0.02~0.04mm (0.0008~0.0016in)
- Inspect the piston ring side clearance.
Using a feeler gauge, measure the clearance between new piston ring and the wall of ring groove.
Piston ring side clearance
No.1 ring: 0.04~0.085mm (0.0016~0.0033in)
No.2 ring: 0.04~0.085mm (0.0016~0.0033in)
Oil ring: 0.08~0.175mm (0.0031~0.0069in)
Limit
No.1 ring: 0.1mm (0.0039in)
No.2 ring: 0.1mm ( 0.0039in)
Courtesy of KIA MOTORS AMERICA, INC.
If the clearance is greater than maximum, replace the piston.
- Inspect the piston ring end gap.
To measure the piston ring end gap, insert a piston ring into the cylinder bore. Position the ring at right angles to the cylinder wall by gently pressing it down with a piston. Measure the gap with a feeler gauge. If the gap exceeds the service limit, replace the piston rings. If the gap is too large, recheck the cylinder bore inner diameter. If the bore is over the service limit, the cylinder block must be rebored. (Refer to IDENTIFICATION OF CYLINDER BORE SIZE )
Piston ring end gap
Standard
No.1 ring: 0.15~0.30mm (0.0059~0.0118in)
No.2 ring: 0.35~0.50mm (0.0138~0.0197in)
Oil ring: 0.20~0.70mm (0.0079~0.0276in)
Limit
No.1, 2, oil ring: 1.0mm (0.0394in)