OMC Sterndrive Identification and what to order upon reinstall after lower unit swap

JeffKingTulsa

Seaman Apprentice
Joined
May 3, 2012
Messages
39
Where to begin....

Have the motor off to the rebuild shop and now working on the lower unit while I have everything torn apart. Last season the boat would motor/boat would jerk quite severely under load/throttle and after reading a few forums this seems to be from bad shift adjustment and/or clutch dog gears slipping. Because the place ripped me off so bad on a trailer to get the boat around on, I had them send me a supposed "good" extra lower unit for it. So I am lucky I guess in the fact that the clutch dogs should be in the lower unit. So the plan is to put back in the rebuilt motor and attach this lower unit to the existing drive and pray everything works all summer our first time out..... ;)

Ok, so the model plate identification tab on the shifter housing in the engine bay is ripped in half of course so I don't have the model number. The plate on the side of unit ( pic attached ) says 983486 but not getting that to pull up on searches. I think I am dealing with an OMC Stringer but beyond that I don't have much knowledge so far

Any help with any of these following needs for the action plan would be awesome!
Needs:

Need to figure out model numbers so can do the water impeller while I am at this whole mess.

What parts do I need to order for water impeller replacement and where?

Actually, What parts do I need to order to replace the lower unit? Any gaskets? rings that a guy should do while in there? Any kits anyone know of?

Think I just have the shifter cable to get out left to take ( think call the lower and upper unit ) off. Need to find last retaining clip. Think under side when motor all the way raised?

Does the piece that (what I maybe incorrectly calling the upper unit) bolts to the upper unit need to come off to do the water impeller?

Again, Thanks a bunch for help with a game plan. Almost worn out from fighting to keep this old classic double deck pontoon going each year.
 

Attachments

  • photo220052.png
    photo220052.png
    903.4 KB · Views: 0
  • photo220053.png
    photo220053.png
    1.2 MB · Views: 0
  • photo220054.png
    photo220054.png
    1.4 MB · Views: 0
  • photo220055.png
    photo220055.png
    1.4 MB · Views: 0

southkogs

Moderator
Staff member
Joined
Jul 7, 2010
Messages
14,785
Your 'toon is a '79, and assuming that's the original drive on her, you've got an OMC hydro-mechanical Stringer 400.

The way you identify the drive is actually by the engine. Mine has a tag on the rear starboard motor mount. Yours should be a 990244S, 990244S1, 990245S or 990245S1. Otherwise the individual Stringers didn't really have model numbers.

Impeller replacement should be THIS kit. The impeller is on the bottom of the upper gear case, and it's a heckuva lot easier to replace while the unit is off the drive.

In your first photo, the upper gear case (upper unit) is what's attached to the trunion points (intermediate housing). The lower unit is what is in your second picture.

I don't know much about your shift system ... totally different than mine.

You're gonna' need a manual.
 

JeffKingTulsa

Seaman Apprentice
Joined
May 3, 2012
Messages
39
Thanks for the response. As I understand it they pieced this thing together like that Johnny Cash - Cadillac song. The drive was an 85 I think they said but yes the engine is a 990244s1.

Happen to have a link to procedure for the kit? Would like to leave the drive on, just because I am winging this with no experience and just trying to leave as few chances for something to get messed up.
 

southkogs

Moderator
Staff member
Joined
Jul 7, 2010
Messages
14,785
'85 should be full mechanical then. Still a 500, but a different shift all together. I don't know much 'bout that one either. But baby that shift cable - and based on the first photo I'd be a little concerned about it. You can find some exploded views HERE.

You can change the impeller while it's attached, but you'll be workin' on your back upside down.
 

JeffKingTulsa

Seaman Apprentice
Joined
May 3, 2012
Messages
39
Do you mean still a 400? Not sure what a 500 Stringer is. There is a shift cable already attached to the other "newer" supposed good lower unit so I will hopefully just use that.

Yea, that is ok. Already in the grass, shuned to the back lot behind the fence. Might as well be laying down and upside down also lol.

Hey, that link.. ?? I'm not the most familiar on what im supposed to be clicking inside there to get a much need expanded view. Stern drive > 1985 > 302F, 302SP, 302ST ?
 

southkogs

Moderator
Staff member
Joined
Jul 7, 2010
Messages
14,785
Do you mean still a 400? Not sure what a 500 Stringer is.
A Stringer 500 is a typo :rolleyes: - yes, still a 400.

Go to '85, and just about any of the 4 cylinder sterndrives in there will show you what you need to see. Gear ratios are different but the drive is pretty close.
 

JeffKingTulsa

Seaman Apprentice
Joined
May 3, 2012
Messages
39
No Title

1. How do I get this upper housing off the lower unit? I have removed the bolts that face the impeller on the underside of the lip on the top of the lower unit but it still seems pretty solid on there. Even the ones behind the little circular plate with the fin on it.

2. Should I have a seal kit also while redoing the water pump and switching the lower unit.
 

Attachments

  • photo220753.jpg
    photo220753.jpg
    71 KB · Views: 0

southkogs

Moderator
Staff member
Joined
Jul 7, 2010
Messages
14,785
The unit that sat where in the space in your photograph is where the impeller should be. If I'm seeing things right, that's your exhaust housing sitting on top of your lower unit. I'm not sure all of what you need to remove on yours, but mine has another screw on the bottom by the water inlet.

You shouldn't need to take that exhaust housing off for anything with the impeller though.
 

JeffKingTulsa

Seaman Apprentice
Joined
May 3, 2012
Messages
39
No Title

Yea, I have that all out thanks to sterndrive.info youtube video. It is insane whoever designed this thing. Yea, I figured I better do the impeller while I had it apart and it was good I did as 2 of the flaps where a spin away from breaking off. I am also swapping out the lower unit cause of the bad suspected clutch dog as the boat did the big jerk while under throttle and I have another supposed "good" lower unit. In my second picture on my first post, I have all the bolts from the under side of that fin facing up off. Are you saying there is one very long one on the bottom facing up?

I need to get another water pump shaft as the male splines are worn more than half. Trying to decide if I can go with the ball gears with this wear on them. REALLLLLYYYYY don't want to mess with them.
 

Attachments

  • photo220813.png
    photo220813.png
    1.3 MB · Views: 0

JeffKingTulsa

Seaman Apprentice
Joined
May 3, 2012
Messages
39
Sterndrive.info hooked me up with drawings, ball gear kit, water pump drive shaft and all the seal kits. Highly recommend their knowledgeable staff.
 
Top