Piston Ring Measurements

There are some important specifications to check when installing piston rings. One of the measurements in axial clearance. Axial clearance is the distance between the piston ring and ring land. This prevents the rings from binding in the ring land at operating temperature. Axial clearance is measured using a feeler gauge.

Fig 1: Checking Piston Ring Of Feeler Gauge

Courtesy of BMW OF NORTH AMERICA, INC.

Also the piston ring end gap has to be checked. This measurement is checked using a feeler gauge.

This clearance is critical in order to prevent the end gaps from contacting each other when the engine is at operating temp.

When installing the piston rings, always stagger the end gaps as per the repair instructions.

Fig 2: Identifying Piston Ring End Gap

Courtesy of BMW OF NORTH AMERICA, INC.