Whats the purpose?

[mattsanders]

What does the oring at the top of the driveshaft do? Is is a requirement?

 

[1946Zephyr]

Re: Whats the purpose?

The o-ring is more or less a shock absorber for the spline that goes into the crankshaft and it helps keep the drive shaft centered in the crank shaft as well. Without it, the spline on the drive shaft will get beaten up more and create more damage to the inner crankshaft spline and driveshaft spline. Does this make sense to you.

If you should loose the one off of yours, you should be able to buy another one, easy enough. You could also go to the parts house and get a universal type, that matches the same dimensions as your original. The best way to check your dimensions is to measure the thickness of your old one with a dial caliper and get one that fits relatively tight over the end of the spline. I believe the diameter of the o-rings are about .048 to .062, depending on what motor you have. Some could go as high as .080

 

[billy4hp]

Re: Whats the purpose?

I believe it also keeps moisture from creeping up the splines so that the LU shaft doesn't rust weld itself to the powerhead...

 

[1946Zephyr]

Re: Whats the purpose?

Yep, I belive that also is true

 

[emdsapmgr]

Re: Whats the purpose?

Another possibility-it will may help to hold grease/lubricant on the upper drive shaft splines.

 

[F_R]

Re: Whats the purpose?

All of the above.

Fact is, anyone who is familiar with salt water motors knows the reason very well. The crankshaft is made of steel. It sticks down into a very hostile environment. If that hostile stuff gets into the splines, the steel rusts. A few months of that and you can't get the drive shaft out because it is rusted in. Give it a year or two and there will be no splines left and you go nowhere. Many a motor has been carried off to the dump because of a missing 10 cent o-ring.

The only difference between salt water and fresh water??? It just takes longer in fresh water.

 

[kyron4]

Re: Whats the purpose?

How often should this o-ring be checked ? I used marine grade bearing grease on the splines, is this the preferred method? -Thanks

 

[Expidia]

Re: Whats the purpose?

The o-ring is more or less a shock absorber for the spline that goes into the crankshaft and it helps keep the drive shaft centered in the crank shaft as well. Without it, the spline on the drive shaft will get beaten up more and create more damage to the inner crankshaft spline and driveshaft spline. Does this make sense to you.

If you should loose the one off of yours, you should be able to buy another one, easy enough. You could also go to the parts house and get a universal type, that matches the same dimensions as your original. The best way to check your dimensions is to measure the thickness of your old one with a dial caliper and get one that fits relatively tight over the end of the spline. I believe the diameter of the o-rings are about .048 to .062, depending on what motor you have. Some could go as high as .080

Love the bug thing. When I saw it I said where do damn bugs come from in the middle of the winter. I went to squish it and almost broke my screen hahahahha!

 

[F_R]

Re: Whats the purpose?

How often should this o-ring be checked ? I used marine grade bearing grease on the splines, is this the preferred method? -Thanks

It doesn't need to be "checked" as such. What should be done is any time the lower unit is removed, such as for a water pump job, pay particular attention to the o-ring and use a new one if there is any doubt at all about it's condition. And be careful not to knock it off during reinstallation of the lower unit.

The grease should be fine, in most cases. Some motors now get a little pickier about the grease, usually a moly lube. That's for wear considerations.