Bulletin No. 1.62-4 Group No. 1.62 December 10, 1998 Page 1 of 1

OIL CONSUMPTION / WRONG PISTON

JOHN DEERE 4955, 4960 AND 8560 TRACTOR

ENGINE OVERHAUL PRECAUTION

When John Deere introduced the 4960 Row Crop Tractor powered by the 6076A engine, they experienced unusual oil consumption problems. Due to the higher horsepower level of this model, additional heat was absorbed by the liners at the top turnaround point of the pistons. Oil that was brought up to the high-ring pistons for lubrication would burn (flash), resulting in excessive oil consumption.

The problem was resolved by exchanging the newer high-ring pistons for the older design piston with the power top ring. The temperature design goal for the top of the liner was 355° F. or less. The liner temperature of the 4960, when working and fully loaded was 392° F., considerably higher than the design goal. As a result, the oil was lost by burning. The 8560 Tractor was also affected but only by a few degrees.

The purpose of this bulletin is to precaution you when supplying overhaul piston/liner parts for these model tractors. Reliance kits include the more modern high-ring piston design. We do not recommend Reliance NRE-60294 cylinder kits, RP-623 inframe kits, or RP-624 major overhaul kits for use in 4960 and 8560 Farm Tractors. Use of these kits in those applications may result in higher than acceptable oil consumption.