SELECTOR AND PRESSURE CONTROL VALVE GROUP 6P3226 - Caterpillar

Caterpillar: Confidential Yellow
PSP FOR INSTALLATION OF NEW LONGER VALVES IN 3304 AND 3306 NATURAL GAS ENGINES
  The information supplied in this service letter may not be valid after the termination date of this program.   Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.
SUPPORT PROGRAM FOR INSTALLATION OF NEW LONGER VALVES IN 3304 AND 3306 NATURAL GAS ENGINES, 1105, 1100, PS0255 U-56 C-55 Replace Service Letter (PS0255) dated August 28, 1985 with this revised Service Letter. See changes denoted by (right arrow). This Program can only be administered after a failure occurs. Contingent damage will not be allowed. The decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS0255" as Part Number and "7755" as Group Number. Termination Date
(right arrow) December 31, 1986
Problem
The exhaust valves in the following 3304 and 3306 Natural Gas Engines can stick open during operation. The cause of this is a build up of dried, hardened oil in the valve guide. New longer valves valve guides, spring spacers and rod assemblies (push rods) along with several other parts are now (right arrow) used in production on these engines. A remanufactured cylinder head with the new components is available for the 3306 Natural Gas Engine.
Affected Product
Model Identification Number 3304 Natural Gas Engine 37Y506-847, 849, 850, 852-979, 981-985, 987-997, 999, 1001-1017 3306 Natural Gas Engine 7Y291-2040, 2042-2051, 2053-2057, 2059-2062
Parts Needed
The following parts should be installed only if the exhaust valves on the engine are sticking. 3304 Natural Gas Engines 4 - 7W7491 Valve (Exhaust) 4 - 7W7490 Valve (Intake) 8 - 7W7489 Guide 8 - 7W7488 Spacer (Spring) 1 - 7W7537 Cover Assembly 4 - 2H3756 Bolt (Head) 1 - 7W7480 Dowel 8 - 2W7047 Rod As. 2 - 7W7484 Bracket (Middle) 1 - 7W7483 Bracket As. (Front) 1 - 7W7479 Bracket (Rear) 1 - 8M4448 Seal 1 - 6V2502 Valve Grinding Gasket Kit (right arrow) 3306 Natural Gas Engines 1 - 0R1371 Cylinder Head Grp. - Remanufactured 1 - 7W7539 Cover Assembly 6 - 2H3756 Bolt (Head) 1 - 6V2981 Valve Grinding Gasket Kit 1 - 8M4448 Seal 1 - 6V1279 Aftercooler and Aftercooler Lines Gasket Kit (if applicable) 1 - 7W7483 Bracket Assembly (Front) 1 - 7W7479 Bracket (Rear) 12 - 2W7047 Rod Assembly 1 - 7W7480 Dowel 4 - 7W7484 Bracket (Middle)
Action Required
If the exhaust valves on a 3304 or 3306 Natural Gas Engine are sticking open, install the listed parts. 3304 Natural Gas Engines Only The 7W7488 Spacers are used under the valve springs to maintain the correct spring height. The new valve guides are longer and must be installed to the dimensions shown in the illustration. A 7S8859 Driver Assembly,