Upper gearcase seal replacement on '79 Stringer 800

[Nivekt]

My seals are leaking and its time to replace them. The water intrusion is pretty bad. After one trip out on the lake the upper gear oil will turn completely milky. I pressure tested it and it will not hold for any length of time. I did notice that the air would leak out around the exhaust housing cover.

I did some looking around and found the seal kit to order. I know that I would have to remove the whole drive so that I could remove the upper gear case portion and then reseal. What I cant figure out by looking at the kits is exactly which seals in the exploded parts diagram are included in the kit.

Would someone mind taking a look at the picture and tell me exactly what numbers are being replaced with the kit?

Also, as a test to nail down exactly where my leak is occuring, I would like to just remove the exhaust housing cover(#72) without removing the entire drive and try to replace any seals in that immediate area. Like I stated earlier, I can see and hear the air/milky oil pushing out from around that cover when I pressure tested the upper. Is it possible to remove just this exhaust cover without taking the entire drive off?

*EDIT* Correct exploded parts diagram for my particular setup added below.

*EDIT* Correct exploded parts diagram for my particular setup added.

 

[Nivekt]

Re: Upper gearcase seal replacement on '79 Stringer 800

Bumping for help.

 

[Howard Sterndrive]

Re: Upper gearcase seal replacement on '79 Stringer 800

before you reseal, you might want to check how much freeplay there is between your exhaust housing and upper gearcase.

too few shims under the top cover can allow the lower to float around the upper so much that the top cover seal will not seal.
factory manual shows the check procedure and specs for up and down play

seal kit:
http://www.iboats.com/Upper-Unit-Se...6779031--session_id.152417308--view_id.173090

 

[Nivekt]

Re: Upper gearcase seal replacement on '79 Stringer 800

Thanks for your reply Howard. Is the shim you are referring to #28 on the exploded parts diagram?

 

[Howard Sterndrive]

Re: Upper gearcase seal replacement on '79 Stringer 800

no, I don't see it there - but the qty is "as required" whichever part # it is
might be with the cover #72
p.s. that parts drawing is NOT a 1979 - that's an old electric shift

 

[Nivekt]

Re: Upper gearcase seal replacement on '79 Stringer 800

Thanks for the guidance Howard. Ill pop the cover off and see what I have.

 

[floattest]

Re: Upper gearcase seal replacement on '79 Stringer 800

Nivekt,

I think you need a different diagram for a 1979. But the one you have shows an upper that is nearly identical to yours. I use the BRP parts catalog online, it's great. good diagrams and all the parts numbers in easy list. Anyway if your upper truly is leaking around the top cover then I suspect either seal #21, the o-ring that seals the gearbox top cover (#77) or Seal #89, an o-ring that seals between the steering gear (#81) and the Top cover (#77).

As Howard says your Lower/exhaust housing assembly may have too much slop up and down but I don't know for sure that would cause the top of the gear box to leak.

The parts 28 and 34 are shims, not seals, they are the parts that allow for adjusting the free play in the upper to lower connection. The manual gives a range of free float, I don't remember how much it is. Seek the manual.

I think it's possible you could replace seal 21 without removing the drive. remember to shore up the lower unit when you remove the exhaust housing cover. It's going to drop to the ground when the exhaust housing cover screws are removed. Then the gear box cover can be accessed and removed and you'll get into the seals 21 and 89 area. another seal that may be causing leaking at the top of the gearbox is the steering shaft bracket, parts #10 and #17 form a seal at that location. That would be replaceable without removing the drive as well.

You may just want to remove the whole drive and separate the two units and inspect for other leaks.

good luck and happy wrenching

 

[Nivekt]

Re: Upper gearcase seal replacement on '79 Stringer 800

Thanks for getting into the details Floattest. Ill check out the spacing first and then make my decision for what to do next. I need to build a drive stand and I have never taken the drive off before. I'm a little nervous about the cable removal process but I have decent instructions to work with from the Seloc manual and other sources.

Ive been looking around the web for a video or picture tutorial on the cable removal process but can't find anything.

 

[Howard Sterndrive]

Re: Upper gearcase seal replacement on '79 Stringer 800

cable is $600 - when they say take the battery right out of the boat - they mean it!
factory manual is the only way to go imo
this piecing together of info from other sources is not going to save you a nickle

trucourse steering shaft is a common upper leak point - but your drawing above doesn't even have trucourse... get the right info and do the job once

(stepping down from soapbox.....)

 

[Nivekt]

Re: Upper gearcase seal replacement on '79 Stringer 800

cable is $600 - when they say take the battery right out of the boat - they mean it!
factory manual is the only way to go imo
this piecing together of info from other sources is not going to save you a nickle

trucourse steering shaft is a common upper leak point - but your drawing above doesn't even have trucourse... get the right info and do the job once

(stepping down from soapbox.....)

I hear ya loud and clear Howard. Stay up there as long as you need. Im always listening. Ill bite the bullet and get the factory manual. I just wish there was a downloadable copy. This is the correct manual right?: http://www.iboats.com/OMC-Sterndriv...3684647--session_id.865082566--view_id.438319

Oops, wait, or is it this one?: http://www.iboats.com/OMC-Sterndriv...3684647--session_id.865082566--view_id.438320

Last edit, I promise. Looks like I found it for $30 cheaper if this is the correct one: http://www.marineengine.com/parts/p...79&ptype=Service+Manual&Engine=&Model=990257S

 

[Howard Sterndrive]

Re: Upper gearcase seal replacement on '79 Stringer 800

http://www.outboardbooks.com/index.cfm/model/1/308/

or eBay

 

[shrimpman123]

Re: Upper gearcase seal replacement on '79 Stringer 800

you need oring seal #89 in pic, thats the main,culpr,,and common for failure in my experience,definatley if top cover has been removed much at all etc..

 

[Nivekt]

Re: Upper gearcase seal replacement on '79 Stringer 800

Thanks shrimpman. I just pulled the drive this weekend by myself. Man, that was a job! Took me 6 hours but I was also drinking lots of beer and had to build an outdrive stand. lol. Here is the correct exploded view of my exact drive. So looks like Ill be checking out #78 in this case. Im just going to reseal the whole damn thing now that I have the drive removed. It hasnt been done in over three years so It cant hurt. Might as well do the impeller too while Im in there(although it flows fine now). I will also check the freeplay and see If I need to add/remove shims to get it exact as Howard suggested.


Also, should I plan on ordering the impeller kit with the housing as a precaution or just go with the kit that does not have it?

 

[Scott Danforth]

Re: Upper gearcase seal replacement on '79 Stringer 800

make sure you inspect the splines on the end of shafts 35 and where it mates to on shaft 61

 

[Nivekt]

Re: Upper gearcase seal replacement on '79 Stringer 800

make sure you inspect the splines on the end of shafts 35 and where it mates to on shaft 61

Will do Scott. Thanks for the tip.

 

[Nivekt]

Re: Upper gearcase seal replacement on '79 Stringer 800

Well, I got the outdrive off without incident. I will be ordering the impeller and seal kit and would like to know what kind of sealant/gasket compound I will need and where to apply it during these two processes. I know I will need some marine spline grease and that is easy enough to find.

I know that the folks over at sterndrive.com recommend using loctite 680 or 609 compound, but I believe that is only for use when replacing the bearing or oil retainer seals. I plan to leave those alone in this reseal job if they look good.

Thanks for your help.

 

[Nivekt]

Re: Upper gearcase seal replacement on '79 Stringer 800

Alright, here goes...

Disassembled the upper today. When I pried out the bearing retainer, ball gear, etc. I noticed that there were absolutely no shims in there. Is this a problem? Should I reassemble with shims? If so, how many and of what size?

So I got everything apart and noticed that the impeller was in excellent shape for 3+ years old. I've even run the thing dry one or two times for a few seconds on accident.

One of the things that puzzled me is I absolutely could not find the water pump driveshaft retainer clip. It is simply not there. I can only surmise that when my mechanic rebuilt this drive 3 years ago that he forgot to install the clip. The driveshaft o-ring that is splined was pushed up a bit and chewed up. Also, can anyone tell me if my water pump driveshaft is too worn to be reused?

Ive cleaned everything up real well and am putting together a parts list. I will, of course be replacing the impeller and housing just to play it safe as well as resealing the drive. I can take additional pictures of any part if that would help you in aiding me with anything else. Thanks for your help.

 

[Howard Sterndrive]

Re: Upper gearcase seal replacement on '79 Stringer 800

If it ran fine under load before with no shims, then leave it with no shims. That's unusual, but probably just what it took to get the tooth contact correct in that particular housing.
The wear pattern on those teeth looks perfect.

If this is a new-to-you drive, then I'd be suspicious seeing that new ball gear and no shims. makes one think they were lost during ball gear service.

The rule of thumb on splines is 20% wear = trash. so, your call based on how many hours per year you plan to boat etc.
"if in doubt, throw it out" is the other rule of thumb

 

[Nivekt]

Re: Upper gearcase seal replacement on '79 Stringer 800

If it ran fine under load before with no shims, then leave it with no shims. That's unusual, but probably just what it took to get the tooth contact correct in that particular housing.
The wear pattern on those teeth looks perfect.

If this is a new-to-you drive, then I'd be suspicious seeing that new ball gear and no shims. makes one think they were lost during ball gear service.

The rule of thumb on splines is 20% wear = trash. so, your call based on how many hours per year you plan to boat etc.
"if in doubt, throw it out" is the other rule of thumb

Thank you Howard. I ran the drive into a rock 3 years ago and cracked the upper gear case housing. I had my mechanic source a new housing and swap over my internals. That was the last time it was taken apart. I have no idea about the ball gear having been replaced at that time. They certainly didnt charge me to do that so Im sure it is the same ball gear that was there when I bought the boat. I am extremely careful about engaging the drive and the boat has only had about 60 or so hours on it in the time Ive owned it. I do have the some of the previous 2 owners repair invoices and dont see any mention of a ball gear replacement in them. Im sure these arent the original ball gears though as the boat had about 560 hours on it when I bought it....that is if you trust the counter.

Here are some better pictures of the ball gear. Its not completely free of wear...

Ill go ahead and replace the water pump shaft. Im a little uncomfortable with the wear it has and the fact that this boat is going to see a lot of hours for the remainder of this season and the next.