Technical data

ManualsBrandsVolvo Penta ManualsAutomotiveTAMD70D

Design and function

Pistons

The pistons are made of light metal alloy. The top

compression ring, which transmits the majority of the

heat which is transferred via the pistons, is located in

a ring carrier made of high alloy special cast iron,

which is cast in to the piston. This gives the piston

ring groove long service life despite the heat loading.

The piston ring grooves for the other pistons are ma-

chined directly into the piston.

The pistons also have a circular space inside the up-

per part of the piston, through which the oil for piston

cooling passes. On the pistons for the 6(x) series,

there is an expansion area in the gudgeon pin hole

(“side relief”), which reduces the stresses on the pis-

ton during the combustion process. The same advan-

tages are achieved on the 71 and 72 engines by

means of a trapezoid con rod end.

The combustion chamber is entirely contained within

the piston crown.

Pistons and cylinder liners are only stocked as com-

plete sets for spare part purposes.

Piston design

A Combustion chamber diameter*

B Combustion chamber depth*

C Ring carrier

Piston ring profiles

TAMD 63

TAMD 61, TAMD62

Piston rings

6(x) series

Each piston has two compression rings and one oil

scraper ring.

On the TAMD61, TAMD62 and TAMD63, the top com-

pression ring is of the “Keystone” type (trapezoid)

The ring has a molybdenum coating and must be in-

stalled with the TOP marking upwards.

The second compression ring (chrome plated), which

is slightly conical and has a turned internal chamfer,

must be installed with the TOP marking upwards.

The oil scraper ring (chrome plated) may be installed

either way up.

The ring has two scraper edges which are pressed

against the cylinder wall, both by the spring force of

the ring itself and by an expansion spring located in-

side the scraper ring. The opening in the expansion

springs should be located diametrically opposite to the

gap in the oil rings*.

* TAMD63: The white paint spot on the spring should be visible

through the outer ring gap.

Gudgeon pin hole with “side relief”