COUPLING AS 5053912 - Caterpillar

3406, 3408, 3412 EnginesSUPPLEMENT: 06/17/85SERVICE MAGAZINE, SEPTEMBER 6, 1982, PAGE 4.In the article "Improved Inlet And Exhaust Valves", the last paragraph should read as follows. When reconditioning 3408 and 3412 Vehicular Engines, Caterpillar recommends NOT to reuse the former 4N5654 Inlet Valves and 7N4580 Exhaust Valves. Also, do NOT reuse the former valves in other 3400 Series Engines if the valves have previously been used in a 3408 or 3412 Vehicular Engine. The former valves from all other 3400 Series Engines (except 3408 and 3412 Vehicular Engines) can be reused if the valves are in usable condition. See the Guidelines For Reusable Parts "Valves And Valve Springs," Form SEBF8002, and "Valve And Valve Spring Specifications", Form SEBF8034.
--------------- END SUPPLEMENT ---------------Description of Change: New inlet and exhaust valves are used in the above engines. The new valves have improved steel for this application that will give longer service life to the valves.Adaptable As: The new 1W3859 Inlet Valve and the new 1W3860 Exhaust Valve are direct replacements for the 4N5654 Inlet Valve and 7N4580 Exhaust Valve, respectively. The former valves are canceled. When reconditioning the above engines, the former valves can be installed again if they are in usable condition. See the Guidelines For Reusable Parts "Valves And Valve Springs", Form SEBF8002, and "Valve And Valve Spring Specifications", Form SEBF8034.