Detroit Diesel — Replacement of Piston Ring
Maintenance
From a Detroit Diesel service manual — check it applies to your exact model before use.
Before you start
- Be careful not to over-expand the rings during installation.
Procedure
- Remove the piston.
- Remove the piston rings using ring pliers J-46072, in order from the top of the piston down.
- Clean all the carbon from the ring grooves; ensure grooves are not damaged.
- Before installing new rings, check the end gap.
- Remove the garter spring from the third (lowest) ring to measure its end gap.
- Install the garter spring; the joint should be 180 degrees from the gap in the piston ring.
- Set the maximum ring expansion stop on the ring pliers to the piston diameter.
- Make sure the word TOP on each ring faces toward the crown of the piston; install rings bottom to top.
- Offset the ring gaps alternately by 120 degrees.
- Install the piston.
Tools required
- J-46072 ring pliers Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Keystone Groove I end gap when new 0.45 to 0.60 (0.018 to 0.024) mm (in.); maximum 1.0 (.039)
- Taper-Faced with Internal Angle Groove II end gap when new 0.40 to 0.55 (0.016 to 0.022) mm (in.)
- Double-Chamfered Oil Control with Garter Spring Groove III end gap when new 0.40 to 0.55 (0.016 to 0.022) mm (in.)
Source: Detroit Diesel service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.