SEAL-O-RING 6D7889 - Caterpillar

3508, 3512 EnginesSUPPLEMENT: 11/00/91Engine News, April 1991, Page 1, "New Cylinder Blocks And Crankshafts Used" on 3508 and 3512 Engines.In the heading of the third column in Chart C, disregard the number .635". The correct number is 0.635 mm (.025").
--------------- END SUPPLEMENT ---------------Description of Change: A change has been made to crankshafts for the 3508 and 3512 Engines. In addition, new cylinder blocks are used to accommodate the changes to the crankshafts. The change is: ... New crankshaft counterweights are forged steel and have a 225 mm (8.9") outside radius in all 3500 Engines. The former crankshafts used counterweights made of plate steel with a 222 mm (8.7") outside radius. These new counterweights have more mass than the former counterweights which will improve the crankshaft balancing process in the factory. With the former counterweight, it was necessary to remove a portion of the outer end of some counterweights on 3508 crankshafts in order to balance the crankshaft assembly.
New parts service crankshaft groups will use the new forged counterweights with an outside radius of 222 mm (8.7") to service the former crankshaft groups.
The new cylinder blocks have material machined off to provide clearance for the larger crankshaft counterweights.
Adaptable To: Chart A identifies the changes to cylinder block part numbers. Chart B identifies the effectivity of the new cylinder blocks.
Chart C identifies the new crankshaft assemblies and the parts service crankshaft assemblies.
The new crankshaft assemblies [with the 225 mm (8.9") radius counterweight] MUST NOT be used with the former cylinder block assembly. The larger counterweight could hit the former block and cause it to crack. The new block can be used with both the new and former crankshafts. Chart D identifies the new and former crankshaft assemblies with a 222 mm (8.7") radius.
Chart E identifies the effectivity of the new crankshaft assemblies.