PLATE (L.H.) 6S3237 - Caterpillar

3306, D330C, And D333C Industrial And Marine Engines Equipped With 7N5908, 7N5909, 7N6206, 7N6208, or 7N6210 Water Pump GroupsDescription of Change: An outlet pipe with an orifice is now used in the regulator and housing groups for the cooling systems on the above engines. The 28 mm (1.1") orifice in the outlet pipe is a restriction to the coolant flow. This slows the coolant flow rate to permit better venting (discharge of air in solution in the coolant into the air chamber at the top of the radiator).
Formerly, a pipe without an orifice was used. In certain heavy load applications, it was possible for the coolant to flow fast enough to prevent good venting. Too much air held in solution in the coolant some times caused water pump cavitation (reduction of water flow). The result was engine overheating.
Adaptable As: The new 8N888 Regulator and Housing Group is a direct replacement for the former 3N3271 Regulator and Housing Group which is canceled. If desired, conversion of the former 3N3271 Regulator and Housing Group to the new 8N888 Regulator and Housing Group is possible. To make the conversion, remove the 1P9989 Pipe and install a 8N743 Pipe in its place. If an engine has combustion gas leakage into the cooling system and/or if the radiator cap does not hold pressure, check for high operating temperatures and low cooling system pressure. High operating temperatures and low cooling system pressures are conditions which can cause water pump cavitation. If the operating temperatures are high and the cooling system pressure is low, it is Caterpillar's recommendation to install an outlet pipe with an orifice.