Cummins/Onan 6.5NH - 3CR / 6000 A — Piston Ring Fitting and Installation
Repair & overhaul · Piston rings
For the Cummins/Onan 6.5NH - 3CR / 6000 A, from the Cummins/Onan service manual.
Applies to: Cummins/Onan NH engine
Procedure
- Check each ring gap by placing the ring squarely in its cylinder at the bottom of its travel.
- File slightly oversize rings as necessary to obtain the correct gap; do not use rings requiring too much filing.
- Standard size rings may be used on .005 inch oversize pistons; .010, .020, .030 and .040 inch oversize rings go on corresponding oversize pistons.
- Install tapered type rings with the top mark toward the closed end of the piston.
- Space each ring gap one third of the way around the piston from the preceding one, with no gap in line with the piston pin.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Piston ring gap 0.010-0 FridayParts $69.58.020 inch
- Ring side clearance 0.006 inch (top compression ring only)
Source: Cummins/Onan 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.