1901-1953 Indian Motorcycle – Parts – Accessories

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126 – Motors Wet Sumping 1941


By wet sumping, we mean that too much oil is carried in the crankcase, which has been found to be caused by one or more of the three following conditions, which we have found to exist in some of the 1941 machines.

  1. The sump valve pick-up tube can be installed in the motor in such a way that the opening at the end of the tube
    is too close to the bottom of the crankcase. To correct this condition, remove the oil level screw from the left half crankcase and insert a thin screwdriver or any long bent instrument through this screw hole and pry up on the end of the sump pick-up tube until it is about 1/8 to 3/16 above floor of crankcase.
    If you should not be able to raise this tube sufficiently, it will then be necessary to remove the sump valve and cut off a portion of the tube at the bend so that there is a full opening.
    By this tube being too close to the crankcase at the opening, it of course restricts the amount of oil which can be picked up through the sump valve, causing the motor to overload in speed above 50 miles per hour.
  2. It has also been found that the tube which is on the inside of the sump housing is too long in some cases, which also restricts the flow of oil. There should be 3/16 of an inch clearance between the end of the tube in the sump housing and the bottom of the housing itself.
    If there is not this clearance, a piece should be cut off from the end of this tube.
  3. The surface of the sump valve disc may be found to be uneven, which of course will not give proper seating on
    the back plate. If this condition exists, regrind the disc by using fine valve grinding compound. This may be done by placing the disc, with the compound, on a surface plate or sheet of plate glass, revolving the
    disc with the index finger until it has a smooth surface.

To check the sump valve before reassembling to the motor, the sump valve should be fully assembled and oil pressure applied to the return nipple opening. If the valve is seating satisfactorily, it should hold 8 to 10 pounds of pressure.

C. E. Raymond
Service Manager

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