OMC Cobra Upper Shelled, Now what? Rebuildable?

[redblur]

It's a 1986 Ebbtide 19' cuddy with a 4.3 Cobra<br /><br />This afternoon while turning sharp at low speed I heard two loud "clunks" then at idle it was making some strange noises from the drive. We limped it back and put it on the trailer. When I got home I found metal in the oil so I took the cover off to find the upper gears shelled. Not enough beer to make the feeling go away, the worst part is the kids and wife love to go boating and with the Minnesota boating season rapidly winding down, we're out for the season. But I digress...<br /><br />I've got a few questions? What would make the unit "un-rebuildable"? <br /><br />Based on my snowmobile experience I know you can't have an upper part of an engine (or stern drive I assume) shell without metal getting into the lower. So, I assume the lower will need to be rebuilt too?<br /><br />I've been looking at T.C. Electronics and Marine and it looks like it will be worth fixing the boat rather than selling as is or junking. Any thoughts?<br /><br />What in the heck could have caused it? Here's the possible culprits I've thought of.<br /><br />I changed the lower unit oil a month ago, But I filled it according to the manual (pumped it up from the bottom, then after running it it was only down 1/2" so I topped it off)<br /><br />I hit some rocks a couple weeks ago. Banged up the prop enough to cause a vibration, so I put a different prop on and the vibration seemed to go away.<br /><br />Recently, if you turned hard to port or starboard it would vibrate a little. I assumed this was ujoints and was planning on changing them ASAP. Could the ujoints have cause this or do you suppose the vibration was this going all along?<br /><br />One last question. If I get the upper and lower rebuilt, and replace ujoints, gaskets, belows, etc, when putting it back on that should be it right? I just don't want to spend the money only to find out I've miscalulated and need another $1000 in parts.

 

[DHPMARINE]

Re: OMC Cobra Upper Shelled, Now what? Rebuildable?

Generaly things become un-rebuildable when parts and labor become greater than the cost of a new asembly.In the case of a Cobra,a new assembly may not be available (Bombardier doesn't support stern drives) So rebuild maybe the only way.<br /><br />If you go this route,you will need some special tools that may make you wish you had a shop do the work.<br /><br />As for changing the gear oil,I believe OMC changed the proceedure.Pull top plug (dip stick) and drain from bottom plug.refill from middle plug until full(at dip stick)<br /><br />DHP

 

[KaGee]

Re: OMC Cobra Upper Shelled, Now what? Rebuildable?

Based on my snowmobile experience I know you can't have an upper part of an engine (or stern drive I assume) shell without metal getting into the lower. So, I assume the lower will need to be rebuilt too?<br />

Not so with this drive.<br />Units are separate. <br />That said, I would wonder what, if any wear problems you have down there. If you get the upper rebuilt, spend some more and at least have the lower inspected and resealed.

 

[Lou C]

Re: OMC Cobra Upper Shelled, Now what? Rebuildable?

Although the lower and upper are seperate, they share the same oil supply, so wear particles from the upper gears could get into the lower unit. Hitting a rock could have fractured the lower gears enough to lose a chip from one and that could have jammed itself inbetween the gears. Are you sure that you filled properly, you are supposed to fill it from the hole that is near the anti ventilation plate, not the lowest hole on the lower. Most small block Cobras take 64 oz of gear oil. <br />I'd check around, you may be able to find someone who can rebuild it locally, the main thing is if they can get OMC parts. There are many places on the net that sell rebuilt upper and lowers and complete drives, but it is pricey. I'd try Doug Russell in Mass, I got some hard to find manifolds for the V-6 from them recently.<br />www.dougrussell.com

 

[redblur]

Re: OMC Cobra Upper Shelled, Now what? Rebuildable?

Thanks so much for the help. This board is great.<br /><br />

As for changing the gear oil,I believe OMC changed the proceedure.Pull top plug (dip stick) and drain from bottom plug.refill from middle plug until full(at dip stick)

I missed typed, yes thats how I filled it (from the middle hole). I was very consious of the amount which was right around 62 oz.<br /><br />

Not so with this drive.<br />Units are separate.<br />That said, I would wonder what, if any wear problems you have down there. If you get the upper rebuilt, spend some more and at least have the lower inspected and resealed.

Yep, I know they're seperate I guess I just meant as Lou C said that metal floating through the oil even for a short time spells trouble. I see that in the big scheme of things having the lower gone trough will be a minor expense (unless there's major problems there too)<br /><br />I bought the boat for about $1500 less than what I thought it was worth so while I'd rather not, I'm probably ok spending the money to fix it. But my idea of running it for a year or two then selling for what I've got into it is out the door!

 

[seahorse5]

Re: OMC Cobra Upper Shelled, Now what? Rebuildable?

Almost any time a Cobra upper gear set fails, it is due to incorrect filling of the gearcase.<br /><br />Ever since new, the Cobras required filling from the middle screw hole until the proper level using the upper dipstick.<br /><br />If filled from the bottom hole until the dipstick reads will result in a low oil level when the motor is run due to air pockets in the lower drive. The oil level drops and the gears run dry and self destruct. Sometimes they flare out and cannot be removed from the housing.

 

[cslaufer]

Re: OMC Cobra Upper Shelled, Now what? Rebuildable?

Hi I see so many posts where people have not refilled their Cobra outdrives correctly and inturn they are destroyed cost $$$$, I manfactured a external oil resivor for my Cobra outdrive, Very similar to the ones that some mercruisers use, By having one of these it allows you to monitor the oil level in your outdrive from inside you boat, also there then no reason for you not to check the oil level before you use it. I just removed the Outdrive dipstick and inserted a hose fitting in it place, connected a piece of hose to it, I drilled a hole through the transom pushed the hose through the hole and then fitted my cannister to the inside if the transom aprox. 2 feet about the outdrive. I still refill the outdrive through the middle hole in accordance to the OMC manual. But this way I can also monitor it very easily. I think all cobra owners should consider this. This way over filling you outdrive will not cause a problem when the oil expands.