Need help I O-ring found in Lower unit?

[mtcabinfever]

I found a loose o-ring in the lower unit when I change impeller and not sure were it went or on what shaft of my 1953 Big Twin 25hp.

 

[Mas]

Re: Need help I O-ring found in Lower unit?

There's an o-ring sits in a groove on the top of your driveshaft spline. It needs to be replaced if missing. Drop the LU and check. Make sure you also put some molylube on the sides of the splines on reassembly.

Mas

 

[mtcabinfever]

Re: Need help I O-ring found in Lower unit?

IS this groove in the middle of the splines or at top above or below splines?

 

[F_R]

Re: Need help I O-ring found in Lower unit?

It is at the bottom end of the splined area. You can't miss it. Make sure that o-ring is in excellent condition, or replace it. It shouldn't have fallen off. Part number is 303059 (18-7134 here at iboats)

 

[mtcabinfever]

Re: Need help I O-ring found in Lower unit?

Does anyone have a picture of spline and where about this goes. Service Manual is no help.

There's an o-ring sits in a groove on the top of your driveshaft spline. It needs to be replaced if missing. Drop the LU and check. Make sure you also put some molylube on the sides of the splines on reassembly.

Mas

 

[Mas]

Re: Need help I O-ring found in Lower unit?

Well, I do not have a pic of your motor, but here is a pic of a '57 35HP showing the groove where the o-ring slips into near the top of the driveshaft:

Mas