D348, D349 Industrial, Marine and Truck Engines
Description of Change: A new oil jet tube is used in the cylinder block for the above models. The new tube assembly uses a smaller diameter tube than the former tube assembly, and the tube is bent differently. This gives more clearance to prevent possible contact with the pistons and/or connecting rods. Also, with the tube bent differently, the flow of oil hits the piston in a better location for improved cooling. Formerly, it was possible for the pistons and/or connecting rods to make contact with the oil jet tubes, and either bend or break the tubes. Either a bent or broken tube causes piston seizure.
Adaptable As: Direct replacement. The new 8N2975 Oil Jet Tube Assembly can be installed in place of the former 4N8986 Oil Jet Tube Assembly, which is canceled. A quantity of one is needed per cylinder.
The new tube assembly is in effect on engines with the serial numbers shown in the chart.