VALVE GP-PRESSURE REDUCING 1229804 - Caterpillar

Family Of EnginesReference: Service Magazine, December 15, 1986, Page 10, "Avoid Oil Contact With New Water Passage Seals Used In Cylinder Head Groups".The 3400 Family of Engines use Ethylene Propylene Diene Modified (EPDM) rubber water seals on all new engines. These 4W1055 Water Seals resist taking a permanent set when they are exposed to steam in the cooling system. But, these seals cannot be used where they can come in contact with fuel or oil. The EPDM rubber seals will soften and swell if they come in contact with fuel or oil or cooling system lubricants. A new silicone rubber 7C9912 Water Seal is now available for parts service. The silicone rubber water seal can be used if the seal will come in contact with fuel or oil during a rebuild. Care should still be taken to keep the cooling system free of oil, fuel or lubricants to ensure the life of the EPDM liner O-ring seals.