Piston Ring: Service and Repair

PISTON RING FITTING





1. Wipe cylinder bore clean. Insert ring and push down with piston to ensure it is square in bore. The ring gap measurement must be made with the ring positioning at least 12 mm (0.50 in.) from bottom of cylinder bore. Check gap with feeler gauge (Fig. 71).





2. Check piston ring to groove clearance (Fig. 72).

REMOVAL
1. Remove piston and connecting rod.





2. Remove No. 1 and No.2 piston rings (Fig. 73) from piston using a ring expander tool (Fig. 75).
3. Remove upper oil ring side rail (Fig. 73).
4. Remove lower oil ring side rail (Fig. 73).
5. Remove oil ring expander (Fig. 73).

INSTALLATION
1. Measure clearance of piston rings to the cylinder bore and piston.
2. The No. 1 and No. 2 piston rings have a different cross section. Ensure No. 2 ring is installed with manufacturers I.D. mark (dot) facing up, towards top of the piston (Fig. 73).

CAUTION: Install piston rings in the following order:

3. Oil ring expander.
4. Upper oil ring side rail.
5. Lower oil ring side rail.
6. No. 2 Intermediate piston ring.
7. No. 1 Upper piston ring.





8. Install the side rail by placing one end between the piston ring groove and the expander. Hold end firmly and press down the portion to be installed until side rail is in position. Do not use a piston ring expander during this step (Fig. 74).
9. Install upper side rail first and then the lower side rail.





10. Install No. 2 piston ring and then No. 1 piston ring (Fig. 75).





11. Position piston ring end gaps as shown in (Fig. 76).
12. Position oil ring expander gap at least 45° from the side rail gaps but not on the piston pin center or on the thrust direction. Staggering ring gap is important for oil control.