Broken drain/vent on 1987 OMC Cobra

Kim1349

Cadet
Joined
Jun 25, 2008
Messages
21
When winterizing last fall, we pulled what appeared to be a drain plug from the port side of the Outdrive. This is on the middle unit, not the gimbal and not the lower unit. It is mid casting. If you look at the other side there is a OMC logo and this drain/vent is on the opposite side but in the same location as the logo.

When we screwed it out, water came out. When we went to put it back it, it's like the threads have disapeared. All there is now is a plastic circle about 1/16 thick and no threads.

I find nothing anywhere on the drawings or in the manual showing anything like this on the side there. I am not talking about the oil fill/drain now that is elsewhere.

Can someone please tell me what this is and how to fix it?
 

a70eliminator

Captain
Joined
Sep 9, 2007
Messages
3,688
Re: Broken drain/vent on 1987 OMC Cobra

Plug the hole with a rubber expansion plug. Or remove the drive and fish out the threaded nut that dropped when you unscrewed the bolt and is now laying useless in the bottom of the cavity.
Use the search option and you'll get about a 100 hits on that very same topic.
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: Broken drain/vent on 1987 OMC Cobra

Howdy,


You have just joined " I removed the NEVER-REMOVE plug " club!

This usually happens when you don't have a service manual and you're attempting to service the unit without having all the info to do it!

Relax you're among friends! (although I never did remove mine!!)

It's also not the end of the world either......But you do have to remove the drive to get into that area to reinstall the nut on the other side.

I don't think anyone really knows why that hole is there. Most of them are covered by the OMC logo. The logo on a lot of them has fallen off and the screw driver blade slot is just too tempting for most people unfamiliar with the Cobra to leave alone!!


Anyway, pull the drive and replace the screw/nut and don't do it again!

Get yourself the correct OEM manual so you don't join the "I filled the drive with oil like a Mercruiser" club and destroy it in the process!


Cheers,

Rick
 

boatguya1

Chief Petty Officer
Joined
Apr 24, 2009
Messages
444
Re: Broken drain/vent on 1987 OMC Cobra

That second club costs alot more to join. Most I know joined it the filled the cobra like I did my Johnson/evinrude outboard lower unit/ what do you mean I did it wrong and caused all that damage route. I had one cust a few years ago did it to both drives of a twin he just bought.

James
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: Broken drain/vent on 1987 OMC Cobra

Yeah

It happened to my King Cobra.....TWICE!

Only it was a "Dealer" that did it both times!!!(different dealer though)

Well the first time the dealer didn't bother to put oil in it all, The second dealer filled it like a Merc. and it destroyed the upper.

Both dealers replaced the drive both times without my brother (the previous owner) having to "Lawyer-up"......when I got the boat the drive had less than 200 hrs on it! I thought I got a pretty good deal on that one!!

I was a little disillusioned with Four Winns dealers after that though.......


I change my own engine and drive oil .
 

Kim1349

Cadet
Joined
Jun 25, 2008
Messages
21
Re: Broken drain/vent on 1987 OMC Cobra

Ok. Many thanks for the replies. Oh, and I did search and found nothing. I must not have worded it correctly. Oh well.

Now you have me wondering what your talking about filling it like a Merc? And yes I will get a book for it, thanks!

:eek:
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: Broken drain/vent on 1987 OMC Cobra

Yes, you need to get the correct OEM service manual before you starting doing "things" to it!

"Filling it like a Merc" (from the drain) will trap a rather large bubble of air in the drive that will eventually make it to the top, uncovering the upper gears and bearings.

They'll self destruct shortly after that and take out the rest of the drive.

It's not pretty.....it IS expensive.

The OMC service manual outlines the correct procedure to fill the drive.


Cheers,

Rick
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
11,798
Re: Broken drain/vent on 1987 OMC Cobra

Yes, you need to get the correct OEM service manual before you starting doing "things" to it!

"Filling it like a Merc" (from the drain) will trap a rather large bubble of air in the drive that will eventually make it to the top, uncovering the upper gears and bearings.

They'll self destruct shortly after that and take out the rest of the drive.

It's not pretty.....it IS expensive.

The OMC service manual outlines the correct procedure to fill the drive.


Cheers,

Rick


If you need to change the drive oil, and can't find a factory manual quick enough.....
go over to
www.crowleymarine.com
look in product support....OMC drives and you will see the Cobra oil change procedure (factory pages and pics) as well as the R+R prodecure....which is what you need to do to fix the screw you removed.....Mine doesn't have the OMC badge over it....but I resisted any urge to touch it....and the funny thing is that the OMC shop manual good as it is, doesn't say a thing about this, it is only referenced in some of the parts manuals that you can see on crowley marine and doug russell marine....so fix it and leave it alone....
 

grooter

Cadet
Joined
Jul 30, 2013
Messages
9
I have 1990 donzi with this same issue..... When winterizing the unit the antifreeze was leaking around it so I tried to loosen if and it feel apart!!!! If I can get the backer nut fished out I can put in a expansion plug and be good to go?????
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
11,798
No you need to fix it the right way. If that plug pops out at speed you will lose all of your cooling water out that hole and overheat the boat in a heartbeat. Pull the drive, do it right and do the drive maintenance at the same time (supposed to be done yearly)
 

grooter

Cadet
Joined
Jul 30, 2013
Messages
9
Where does one get the correct parts seeing how this isn't listed in any of the manuals....??
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
I have 1990 donzi with this same issue..... When winterizing the unit the antifreeze was leaking around it so I tried to loosen if and it feel apart!!!! If I can get the backer nut fished out I can put in a expansion plug and be good to go?????
Howdy, Welcome Aboard!



First of all, it's really best to start a new thread even though this one speaks to the subject directly. The Forum "rules" are quite specific.


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It's suggested to remove the drive and find the "backer" nut because it could be pumped into the cooling system and plug the t-stat, oil cooler or supply hose etc.....

You can use just about anything to back-up that "screw" (like a small ss plate with a self locking nut) if you cannot find the original one, but it might have gotten into the hose that goes to the oil/PS cooler and into the T-stat housing. If it's lodged in the hose, it could reduce total cooling water flow and cause an overheat.....

You may not be able to actually buy the part. Most of those parts were scarfed up many years ago...... (OMC has been gone for more than 15 years.......)

Regards,


Rick
 
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