Cummins ISX11.9 CM2250 – Service Manual 001-047   Piston Rings

CAUTION  Use a copper or aluminum vise protector when installing the connecting rod in a vise to protect the connecting rod from damage.

When reusing piston rings, be sure the rings are installed on the same piston from which they were removed.

The ring gap of each ring must not be aligned with the piston pin or with any other ring. If the ring gaps are not aligned correctly, the rings will not seal properly.

Install the connecting rod in a vise to hold the assembly in a horizontal position while installing the rings.

A cross-sectioned view of an oil control ring is shown.

The two-piece oil control ring must be installed with the expander ring gap 180 degrees from the gap of the oil ring. Do not overlap the ends of the expander ring.

Each ring has the top marked for correct installation.

Install the piston rings with TOP toward the top of the piston.

NOTE: The oil control ring is not symmetrical for the ISX11.9 and must be installed in the correct orientation.

Use a universal piston ring expander to install the second ring into the piston.

The piston must be held in a horizontal position to install the rings in order to keep the rings in the groove while installing the ring compressor.

The top piston ring (1) is a keystone ring with no twist or cutback notch.

The second ring has a rectangular cross-section (2) with an angled cut (3) on the upper side of the inner diameter to induce a positive twist. This design improves the slobber-resistance of the ring pack.

The oil control ring (4) is the bottom piston ring.

Rotate the rings to position the ring gaps as shown.

The ring gap of each ring must not be aligned with the piston pin, or with any other ring gap. If the ring gaps are not aligned correctly, the rings will not seal properly.

If a malfunction resulted in coolant, oil, excessive fuel or excessive black smoke entering the exhaust system, the aftertreatment system must be inspected. Refer to Procedure 014-013 in Section 14.

NOTE: When installing new piston rings with used liners, higher than average blowby may be experienced for the first several hours of operation. If excessive blowby is still seen after several hours of engine operation, consult the troubleshooting symptom tree Crankcase Gases (Blowby) Excessive in Section TS.