GEAR 7D7607 - Caterpillar

3508 (23Z 70Z),
3508B (4GM, 3DM, 6PN),
3508 equipped with Electronic Unit Injector (EUI) System (5XM, 3LS, 3TS),
3512 (24Z, 67Z),
3512B (8EM, 8RM, 6WN),
3512 equipped with EUI (6PM, 3MS, 3NS),
3516 (25Z, 73Z, 4XF, 5SJ),
3516B (6HN, 7RN, 9AN),
3516 equipped with EUI (7KM, 3NS, 3XS) Generator Set;
3508 (95Y, 68Z),
3512 (49Y, 65Y),
3516 (27Z, 71Z) Industrial;
3508 (96Y, 69Z),
3508B (2BM, 7SM),
3508 equipped with EUI (3PS),
3512 (50Y, 66Z),
3512B (7HM, 4TN),
3512 equipped with EUI (3RS),
3516 (29Z, 72Z, 4MJ),
3516B (8CN, 8KN),
3516 equipped with EUI (3SS) Marine;
3508 (97Y),
3512 (51Y),
3516 (28Z) Vehicular;
G3508 (2JF, 9TG),
G3512 (4KC, 7NJ, 5JD),
G3516 (3RC, 4EK, 8LD) EnginesReference: Engine News; April 1995; Page 7; "Connecting Rod Assembly Includes New Rod Eye Sleeve Bearing".Engine News; December 1994; Page 6; "New Connecting Rod Assembly Has Increased Fatigue Strength".
Engine News; November 1994; Page 1; "Verification of Connecting Rod Eye Bushing Retention When Overhauling Engines".
Guideline for Reusable Parts, SEBF8242, "Verification of Connecting Rod Eye Bushing Retention Using the 5P-8639 Connecting Rod Bushing Press Group".
Guideline for Reusable Parts, SEBF8149, "Specifications for Connecting Rods Used in 3500 Family of Engines".
Illustration 1: New 101-3281 Connecting Rod Assembly.Several improvements to the bolt hole area and the rod eye bushing within the 101-3281 Connecting Rod Assembly have been made on the above 3500 Engines. These improvements, discussed below, increase rod reliability and fatigue strength.
Illustration 2 (Detail A from Illustration 1): Differences between the bottom of the connecting rod bolt hole in the former connecting rod assembly (B) and the new connecting rod assembly (C).An improvement in the manufacturing process has increased the precision with which the bolt holes in the rod assembly are drilled. The four connecting rod bolts are now machined with a full spherical bottom gun drill. (Refer to Illustration 2.) As a result, a reaming step has been removed from the process due to the accuracy of the gun drill.
Another improvement in the manufacturing process is the technique of using a roll tap procedure on the bolt hole threads instead of the previously used cutting procedure.
Both improvements combine to provide a higher fatigue strength for the connecting rod along with a decrease in stress for the bolt hole area of the connecting rod.
Final assembly of the connecting rod includes a "proof test" at room temperature to ensure a minimum interference fit between the connecting rod and the bushing. Previous in this test, movement of the bushing in the connecting rod was not permitted with a proof test of 15 600 220 N (3510 49 lb). The new load restriction has increased to 23 500 220 N (5280 49 lb). In order to prevent connecting rod eye bushing rotation during engine operation after an engine overhaul, the same "proof test" should be performed on each connecting rod using the increased proof load. Refer to the Engine News reference articles and the Guideline for Reusable Parts references within this Special Instruction.
The part number of the connecting rod is stamped on the side of the rod shank followed by a two digit number. The two digit number indicates the change level of the