Specifications, Mechanical: Pistons

Fig 1: Checking Piston Diameter Using Micrometer And Vernier Caliper

Courtesy of VOLVO CARS OF NORTH AMERICA.

Piston diameter (D)

Fig 2: Calculating Running Clearance Of Piston

Courtesy of VOLVO CARS OF NORTH AMERICA.

Piston running clearance (example)

Measured cylinder diameter	81.015 mm
Measured piston diameter	80.995 mm
The piston running clearance is	0.020 mm
The piston running clearance must be 0.010-0.030 mm.

Piston rings

Fig 3: Checking Piston Ring Axial Clearance

Courtesy of VOLVO CARS OF NORTH AMERICA.

Axial clearance B6294S

Upper compression ring........0.030-0.070 mm

Lower compression ring........0.030-0.070 mm

Oil scraper ring........0.038-0.142 mm

Axial clearance B6284T

Upper compression ring........0.050-0.090 mm

Lower compression ring........0.030-0.070 mm

Oil ring........0.020-0.060 mm

Dimensions B6294S

Upper compression ring........1.20 mm

Lower compression ring........1.50 mm

Oil ring........2.50 mm

Dimensions, B6284T

Upper compression ring........1.20 mm

Lower compression ring........1.75 mm

Oil ring........3.00 mm

Piston pin, diameter

B6284T........23.0 +0/-0.004 mm

B6294S........21.0 +0/-0.004 mm