DETROIT DIESEL 53
Each connecting rod (Figs. I and 2) is forged to an "I' section with a closed hub at the upper end and a bearing cap at the
lower end. The connecting rod is drilled to provide lubrication to the piston pin at the upper end and is equipped with a
nozzle to spray cooling oil to the underside of the piston head on engines equipped with an oil cooler. Engines that are
no. equipped with an oil cooler do not use nozzle type connecting rods. An orifice is pressed into a counterbore at the
lower end of the oil passage (in rods equipped with a spray nozzle) to meter the flow of oil.
NOTE: Never intermix nozzle type connecting rods in an engine with non-
nozzle type connecting rods.
A helically-grooved bushing is pressed into each side of the connecting rod at the upper end. The cavity between the
inner ends of these bushings registers with the drilled oil passage in the connecting rod and forms a duct around the
piston pin. Oil entering this cavity lubricates the piston pin bushings and is then forced out the spray nozzle to cool the
piston. The piston pin floats in the bushings of both the piston and the connecting rod.
A service connecting rod includes the bearing cap. bolts, nuts, spray nozzle (if used), orifice and the piston pin bushings
pressed in place and bored to size. The replaceable connecting rod bearing shells are covered in Section 1.6.2.
Disassemble Connecting Rod from Piston
With the rod and piston assembly removed from the engine, disassemble the piston and connecting rod as outlined in
Fig. 1 - Connecting Rod Mounting
Fig. 2 - Connecting Rod Details and Relative
Location of Parts
April, 1974 SEC. 1.6.1 Page 1