BRACKET-PULLEY 4N6841 - Caterpillar

3400 Series EnginesSUPPLEMENT: 04/30/80ENGINE NEWS, MARCH 12, 1980, PAGE 1.In the article "Inspect Regulator Cover Assembly When Overcooling Is A Problem", the 6N362 part number shown in the first paragraph and in the illustration title is wrong. Change the 6N362 part number to 4N362.
--------------- END SUPPLEMENT ---------------In the 3400 Series Engines, one of two designs of regulator cover assemblies is used, according to the type and serial number of the engine. Early 3406 (92U3134 and earlier) Truck Engines and all 3400 Marine, Industrial and Vehicular Engines use a 4N362 Regulator Cover Assembly. This regulator cover has a small hole near the opening for the water temperature regulator. A ferrule is installed in this hole. The ferrule has an orifice to vent (let out) air vapor from the engine. Loss of this ferrule will cause overcooling so inspect the cover to make sure the 2H1193 Ferrule is installed as shown.
The 3408 and later 3406 Truck Engines have a 9N947 Regulator Cover Assembly. This regulator cover does not have a vent hole, and a separate line is used to vent vapor from the engine. If a wrong cover (with a vent hole) has been installed, it will cause overcooling.
Location of 2H1193 Ferrule on the 4N362 Regulator Cover Assembly.