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1990 23 OMC Cobra

I

ivan_deslayer

Member
Hi everyone I'm new to the

Hi everyone I'm new to the board as well as new to the boating life. I recently pickup a 1990 Sunbird w/2.3 liter OMC. The boat is a 16.5f fiberglass boat. The prop on the boat is a 15:1.
Couple of questions the previous owner(PO) claims the engine to be a 128hp engine is it? And what is ie really rated at I kind've think it more on the 105hp side myself. Next question I have. When looking over the out drive with it in the fully "up" position there is a bellow there that I suspect is for exhaust since putting the muffs. is this bellow suposed to have holes in it or not.
 
"The power rating is as staded

"The power rating is as staded 128Hp, but the torque is another thing if You compare to the 3.0/130 hp engines!
The holes on the exhaust bellow is 'relief' holes to reduce the exhaust back pressure when starting and to drain the exhaust system from water when tilting the drive."
 
Thank you. Yes this doesn'

Thank you. Yes this doesn't feel as though there is enough torque to do much with. The PO claims that the original prop was a 21. Is this correct? could the prop indeed be a 21. He changed it to a 13dia x 15 pitch. I'd like to get this thing to "pop" out the water quicker. I don't really care for speed since I'm mostly an inland lake boater.

Any help
Thank you
 
"it sure should "pop"

"it sure should "pop" on a 15p. watch top end revs, that boat should run a 17, or 19. unless You have a pallet of bricks aboard."
 
"Or really heavy relatives. D

"Or really heavy relatives. Don't laugh. I've seen some huge passengers in boats. Each one was like two normal weight people. In that case, you'd need less pitch to get on top.

Jeff

PS: As Scott said, if you pitch down, watch the tach to avoid over-reving the motor and all will be well. Few people run a boat wide open for long!"
 
"Thank you all for the respons

"Thank you all for the response. I kind've have a pallet of bricks along if you will. It's myself, wife, 11 year old and 2 4 year olds. I was blessed that the PO kept ALL the paper work that he had for the boat. And when I say all I even got the original purchase receipt. In the owners manual it did state to keep the RPMs between 45-52k BUT NEVER more than 56K. At about 5k it seems to top out with the 15pt prop not going more that 35. I guess that’s what I’d suspect with that prop. My biggest thing though is the “pop” out of the water. I know the thing is no ski boat but the little woman would like to try I just don’t see it if’n I can’t make’r jump.

Thank you all again,"
 
sounds like You are propped ab

sounds like You are propped about right. one indespensable item for skiing = babysitter.
 
"<[img]"http://www.marineengin

"
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Yeah I was thinking the same thing to get the little woman some practice time. Again everyone thank you. Merry Christmas and I'll probally have more questions."
 
O.K. I said I'd have other

O.K. I said I'd have other questions. As I read through the threads everywhere it says NOT to store the outdrive in the up position. I was unable to do this since I shrunk wrapped the boat and needed to trailer it to storage SO outdrive is in the up position. The outdrive was also shrunk wrapped and AF in it for good measure. Anyway I guess my question is what problems can I foresee when I get it ready for spring?
 
"Walt...During the winter I wo

"Walt...During the winter I would be going through all that paperwork you received and see if you can tell when the bellows, gimbal bearing, lower shift cable, etc were replaced.
Come spring I would remove the drive and check/grease the ujoints, check/grease gimbal bearing, inspect drive bellows, clean/check shift bellcrank, on the drive check the lube level on the dipstick also for water. Drain the drive and replace with fresh lube. Inspect all anodes for wear and replace as necessary. Remove prop and check for any fishing line and grease shaft before replacing prop. Probably a bunch of things as well, strongly recommend a manual, preferrably an OMC factory one, can usually find them on eBay."
 
"The PO gave me an owner’s man

"The PO gave me an owner’s manual, service manual and some other miscellaneous paper work. Nothing major has ever been done to the outdrive as I can gather from all the paperwork. How often do these anodes need replacement? The boat has NEVER seen salt water. I've done the other stuff like changing the lube, checking the seals but I was worried about this bellow issue since I needed to store it in the up position. The prop is currently being fixed for pitting. There was no milkyness (sp?) to the lube. Thank you again"
 
"Sounds like you have a good s

"Sounds like you have a good start on things. As far as the anodes go, it depends on how long your boat is in the water and the quality of the water. Mine is in the water from late April until mid Oct so I change the anodes every 2 to 3 yrs. I suspect yours may spend most of the time on the trailer? if so they should last quite a few years."
 
"Yes the boat is a trailer que

"Yes the boat is a trailer queen
biggrin.gif
. Thank you for all the advice. These bearings that need lubing, removal and inspection along with the outdrive removal. Do you mean the entire outdrive? Or just part of it. Not familiar with the terminology."
 
"Yes...sorry about that but an

"Yes...sorry about that but another good reason for a service manual. The entire drive comes off by dropping the nuts and shaft that attach the trim rams to the drive and then the 6 nylocs that hold it on. The drive slides out from the transom, the drive shaft has 2 ujoints which you will see once the shaft comes out far enough, these need to be greased and normally have zircs on them. The gimbal bearing is the main bearing that supports this drive shaft, it has an external zirc on the starboard side of the transom mount about halfway down, the grease goes through a small tube to get to the bearing, drive does not have to be off to grease this but must be off to inspect it, check for smoothness any pitting, water damage, etc. You will need a new gasket/ oring set to re-install the drive, only a few dollars from a dealer.

ps...try not to remove drive yourself, a little heavy and awkward but can be done, tilt trailer up so the skeg (bottom of drive) is practically touching the ground, that way it doesn't have far to drop when you pull it out."
 
"Bob, Thank you. I haven't

"Bob, Thank you. I haven't been able to check the service manual. Thank you for the pointers though :BIG THUMBSUP:. I know it's only be a couple of months without the boat but MAN I'm getting to itching on dropping it back into the water.

O.K. since I'm a little mechanically inclined I can understand the U-joint stuff. Now the Gimbal bearing this "supports" the drive shaft?

Thank you again.
Walt"
 
The drive shaft basically goes

The drive shaft basically goes through the boat transom into a splined coupler at the rear of the engine however because of the 2 ujoints in the shaft (necessary to allow the shaft to have sideways and up and down movement) it has no support and thats what the gimbal bearing provides. This bearing has to be perfectly aligned with the engine coupler (special tool required)to prevent wear and damage to the coupler itself. Alignment if needed is done by making adjustments to the engine mounts. Not sure what kind of service manual you have but there should be some pictures in there to give you a better idea. You know the old saying "A picture is worth a thousand words"
 
"Bob Thank you,

Yeah I got

"Bob Thank you,

Yeah I got some time last night and was able to sit down and do some reviewing. Makes sense now. The manual I have seems to be an actual service manual. It covers everything from a 2.3 liter up to a 5.8 liter. It does not seem to be a manual for earlier models. I’ve got a cherry picker (engine hoist) so pulling the out drive off seems pretty straight forward. I’ll look at the bellows when I get it apart."
 
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