3406 And 3408 Truck Engines
Description of Change: A different O-Ring seal is now used where the oil pump suction tube connects to the oil pump on 3406 and 3408 Truck Engines. See the illustration. The new O-ring is of a tan color and made from Viton while the former O-ring, which is of a yellow color, is made from Silicone. After a period of time, the O-rings made from Silicone can some times take a compression set and let air get into the oil pump suction line.
Location where O-ring seal is used on oil pump suction tube.