What is the O ring on the drive shaft lower unit for?

[gotjeepzj]

Obviously it seals, but what? 6985ESL

 

[tashasdaddy]

Re: What is the O ring on the drive shaft lower unit for?

if you are talking about the o ring at the top of the shaft, it seals the splines between the drive and crank shafts.

 

[F_R]

Re: What is the O ring on the drive shaft lower unit for?

Leave it out and you will see why the next time you try to remove the lower unit and find the splines are rusted together. OR, leave it go long enough and the splines will completely rust away out of the crankshaft. Then you are dead in the water.

Be sure you smear some grease on the splines and have a Good o-ring.

 

[gotjeepzj]

Re: What is the O ring on the drive shaft lower unit for?

So does the water run up to the point of the O'ring? That seems the only way it would rust. The reason I ask is when I reinstalled my lower unit I forgot to buy a new o'ring. I decided the old one looked good enough to reuse. The propblem was I had to lower the unit several times while trying to align everything and I noticed the o'ring had slipped down the shaft. I'm afraid that it might have slipped the inal time I installed it.

I also didn't grease up the splines, but they still had grease on them from when I removed it.

Guess I'll be taking off the lower unti again to replace the o'ring.

 

[asdasc]

Re: What is the O ring on the drive shaft lower unit for?

On my 59 18HP, I seem to remember that it looked like there was a groove for an o-ring on both ends of the drive shaft, but that only one end seemed to have an o-ring. Is that correct? I can't remember which end I put the o-ring on. I sure hope it was the top. I don't remember greasing it either. When I pull the boat out of the water soon for the winter, I will probably be taking it all apart again anyway.

I can't check the lower unit lube with it in the water, and I have a gut feel that I have some water in there again.

 

[58CorrySuburban]

Re: What is the O ring on the drive shaft lower unit for?

Asdasc,

That is correct, the end of the drive shaft that terminates at the power-head is the end that has an o-ring.

I only know this because I bought a long-shaft motor (though I needed a short-shaft). the guy I bought it from was an "old salt" and gave me the shorter drive shaft. I suspect the the o-ring might be original because the splines where engraved into the rubber.

Of course I looked around for an O-ring that would be a perfict fit, but have only found "mechanics" that may have something ""close?""!!! I don't know about you guys but I dont want to go into the tides, rips, currents and flows without confidence that my little 35 hp motor can see me through (I have a 1958 MFG Corry Suburban).

I hate the fact that there isn't anyone knowledgable in my local area that I can just shoot the s**t with and have them walk me through all the minor specifics.

 

[F_R]

Re: What is the O ring on the drive shaft lower unit for?

So does the water run up to the point of the O'ring? That seems the only way it would rust. The reason I ask is when I reinstalled my lower unit I forgot to buy a new o'ring. I decided the old one looked good enough to reuse. The propblem was I had to lower the unit several times while trying to align everything and I noticed the o'ring had slipped down the shaft. I'm afraid that it might have slipped the inal time I installed it.

I also didn't grease up the splines, but they still had grease on them from when I removed it.

Guess I'll be taking off the lower unti again to replace the o'ring.

Some motors are MUCH harsher on the spline area than others. Your's isn't too bad. The steel crank sticking down to within a few inches of salt water isn't the best of situations though.

Believe me, the most experienced of us wonder if we might have knocked that o-ring off when we install the gearcase. Sometimes we just have to trust ourselves. If the o-ring is new or like new, it usually will stay in place if you are careful. Don't overgrease it either. That can hydro-lock it to where it won't slip in.

Secret confession: I have re- torn down powerheads because I got to thinking, wondering if I torqued the rod bolts. Of course I had, but that is what happens when you think too much.

 

[BaitThrower]

Re: What is the O ring on the drive shaft lower unit for?

On later models they dont even have a groove or O-ring (i.e. my 15hp '86), ya just use a healthy dose of grease on the splines. But if there is a spot on the shaft to put an O-ring, I'd put one there for sure

 

[Rick.]

Re: What is the O ring on the drive shaft lower unit for?

I'm pretty sure the 86 (and later) has an o ring but is up in the top internally. The only way to change it is pulling the power head. Not worth doing unless you have the power head off for some other reason. Rick.

 

[F_R]

Re: What is the O ring on the drive shaft lower unit for?

Agreed, the o-ring is in an internal groove in the crankshaft on newer ones, a DUMB "improvement" if you ask me. Talk about not being sure it is in place!!!

Yeah, yeah, I know it is so the drive shaft isn't weakened by grooving it.