What does this part seal???

[Fishermark]

I am about to reassemble the lower unit to the upper unit on my model 1 Mercruiser. (This is after replacing the water pump assembly). I notice that there is no seal noted in the picture below - where the drive shaft mates with the upper unit. I do believe there is supposed to be a seal there. But just what does it seal? The gear oil is not in that section. Does it just keep water out of that area?

By the way, the best I can determine the serial number is 5620386. There is also a big "8" - hopefully that doesn't mean it is geared for an eight cylinder... does anyone know? Here is a picture:

 

[Don S]

Re: What does this part seal???

Not sure about that big 8, will do a little searching if no one else knows. The seals set up further inside the housing. There are 2 of them.
The oring on the shaft pushes up into the splines a little to hold the grease in and water out. (if it doesn't get pushed down the shaft during install)

 

[ziggy]

Re: What does this part seal???

The seals set up further inside the housing.

?????

(if it doesn't get pushed down the shaft during install)

by the seal in my pic. that i don't see in fishermarks pic...... somethings up and i don't know what...... if i remember right i didn't have a boss to install my seal onto like it appears fisermark has... seems like i could have just pushed my seal right on thru the houseing.... if i remember right...... i put it back together and can't go look anymore......

i think it seals water out. note the black exhust smoke inside on my seal that i been wipeing off.... i think water and exhust are going thru that area on their way out.......

i've no idea about the 8.....

 

[Fishermark]

Re: What does this part seal???

Ziggy's picture shows better where the remains of a seal are on my drive. Here's a pic from the same perspective. (Not nearly as clean! )

Here's a closer picture:

 

[Don S]

Re: What does this part seal???

Well, I screwed up again. Ziggy is probably right, I have to look at a one drive in the morning.

 

[JCF350]

Re: What does this part seal???

#1 drives don't use seals in that area. There is an O-ring that goes in the groove just beneath the splines on the lower drive shaft. Most people have problems with this o-ring staying in place because putting to much grease on the splines will push the o-ring out of its groove before it has a chance to slide into place in female part of the upper drive.

The splines should be "lightly" coated with grease along with the o-ring.
And get the alignment straight when installing (if you fishy feely around to much you'll push the o-ring out of place).

 

[starsnstripers]

Re: What does this part seal???

Like Don and Ziggy said there are two seals one is on the gear housing side to hold gear oil in. It also has to be serviced from the gear side if it's leaking oil. The other is the one in Ziggys picture that keeps water out of the spline and can be replaced from where your looking at it. I can't tell if yours is there it might be deep in the hole. check! The oring on the shaft is (who knows?) merc did away with it, so thats an owner/assembler decision to put it in or not, I think it kinda keeps the grease up on the spline. (my best guess) I'm at the same step process with mine right now. I'd say double check in that hole if not buy the seal clean it best you can and put one in. I think before you do that you can block the oil passage and do a pressure test on the upper housing to see if the inner oil ( gear housing) upper leaks. If it leaks it has to come apart too. Hope it dont! good luck keep us posted Mark.

 

[starsnstripers]

Re: What does this part seal???

Naah I looked at the pics again (with my glasses on) haha! there's a lip there that the seal bottoms out on. Your seal is "gone" clean it up and install one. #26-965031 old#26-37259 Ziggy can varify these he did his.

 

[starsnstripers]

Re: What does this part seal???

Oh as for the "8" I dont think it's an "8" i think it's some type of little emblem mine has gaps in it it looks like your got stamped harder. Not sure what it means. sorry

 

[sterndrive]

Re: What does this part seal???

Gentlemen;
The purpose of the missing/lower seal is to prevent water from reaching the seal surface of the gear above it.
Without that seal in place, the surface will become pitted and you will have a gear fluid leak

 

[Don S]

Re: What does this part seal???

Here is a picture that shows the seal in place on a one drive. Haven't found anything on the 8 yet.

 

[Fishermark]

Re: What does this part seal???

Thanks for putting the effort in Don! It is appreciated.

 

[JCF350]

Re: What does this part seal???

If a seal does go in there then it's a 1A/1B/1C drive or later.

 

[starsnstripers]

Re: What does this part seal???

My #1 drive serial # is 2462278 Alot earlier than yours Mark and mine takes that seal. Suggestion > Where your seal is missing and the surface it fits into looks a little rough you might want to inquire on what kind of sealer/adhesive to use when installing it to help keep it in place. ( if it doesn't fit tight ) Someone on here may have a suggestion what to use for that. Good luck!

 

[Fishermark]

Re: What does this part seal???

Well, I have to modify what I wrote. I said there was no seal there - well, as you can see from the picture it was there... just not much left!

Here's the "seal" I took out compared to the new one:

 

[starsnstripers]

Re: What does this part seal???

Nice photo Don, > Isn't there another seal on the gear housing side? It might be in that photo i cant tell or you just didnt point it out, where as the topic is the lower seal? Wow Mark just the outer shell. Well i guess your new seal should press right in thats good. While were on this area subject I was wondering Don, would you or do you leave out that shaft o-ring when you reinstall the lower unit? Thanks, Mark may want to know this also.

 

[Larson4500]

Re: What does this part seal???

Im dealing with this on my 1982 1R right now. My seal is there but the lower lip is torn. Space is kinda slim up there so first whats the best way to get the old lower seal out of the upper unit and second what do you use to drive in the new seal? Is there some sort of Merc tool or just a good old piece of pipe and a hammer?

 

[ziggy]

Re: What does this part seal???

Im dealing with this on my 1982 1R right now. My seal is there but the lower lip is torn. Space is kinda slim up there so first whats the best way to get the old lower seal out of the upper unit and second what do you use to drive in the new seal? Is there some sort of Merc tool or just a good old piece of pipe and a hammer?

i use a seal puller, just fits up in there...... if the drive is off, i think ya can get in there with a big screwdriver from the ft........ i drive it in witha big socket upside down on an extension.... i think they make a special driver for it though... not sure about that though...... the socket works, but probably not the recommended way....