Reply To: TD20 Leaking Gear Oil???

[John Gragg]

aquasonic wrote:

John, this motor is a little different from the later motors in the mid to late 1950’s. That gasket between the gearcase and the mid-section is critical to seal in the gear oil. Yes, it is open in the back for venting purposes, but the closed front area separates the gear oil from the surrounding water. The gear oil vent screw is above the mating surface of the gasket, so gear oil is present above this gasket also.

It sounds like what you most likely need is a NOS gasket for the gearcase/mid-section mating surface. If I remember correctly, the seal area is separated from the gear oil, so this is why I think it’s most likely the gasket.

I made one of these gaskets once from fiber-rubber gasket material, and it failed when the vapor pressure peaked on a hot summer day. Maybe cork sheeting would work, but the original NOS gaskets definitely work.

Regarding the gear oil, 90W is preferred, but John Deere corn head grease or Lubriplate is ok. This has modern seals, so that’s why gear oil is recommended.

If you end up replacing the gasket, Permatex Ultra Black is hard to beat for a sealant for this application.

Thanks but can you take a look at the parts picture I attached? Am I incorrect in observing that the gasket is installed with the open side to the front (not the back, or prop side) of the motor?

The gasket in there now is a brand new, NOS gasket. I used permatex along the gasket surface, but not the area where a gasket is not involved.

It is my understanding that these parts diagrams use proper orientation (front, back, left, right) with respect to other parts in the drawing?

Lastly, I just thought of this… Regardless if the gasket points fore or aft, what prevents water from flooding the gearcase?

Thanks again.  I look forward to hearing your thoughts.

Best Regards

John Gragg
RIverside, CA

Just starting in the hobby, please be patient.

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