TM 5-2420-230-24-2
Piston Rings (001-047)
B3.9 and B5.9 Series Engines
Page 1-86
Section 1 - Cylinder Block - Group 01
During repair it is essential that the cylinder wall be deglazed
so that new rings will seat against the cylinder wall. Failure
of the rings to seat can result in high blowby and excessive
oil consumption.
Install (001-043-026)
The piston and connecting rod must be installed as an
assembly. Refer to Procedure 001-054.
Piston Rings (001-047)
General Information
The piston ring sets are also different. While both sets
consist of three rings, the top ring of the turbocharged/
aftercooled set has a keystone profile that operates in a
ni-resist insert cast into the piston. The naturally aspirated
top ring is square cut and operates in a groove machined
into the aluminum piston.
NOTE: The top ring for a turbocharged engine is not the
same as the top ring for a naturally aspirated engine.
Inspect for Reuse (001-047-007)
Check the cylinder liners for wear. For those cylinders with
no obvious damage, check the following conditions that
can cause loss of sealing:
1. Piston rings installed incorrectly
2. Worn or damaged piston rings.
NOTE: There are two different designs of intermediate
piston rings used:
Rectangular
Reverse Twist
L-764