OMC Cobra 5.0 Gear Oil Change Tutorial with Pictures

papichuloy2k

Seaman Apprentice
Joined
Nov 8, 2012
Messages
42
Hi everyone,

After reading so many posts from Iboats regarding how to change the gear oil/fluid in a Cobra OMC outdrive, I decided to get to work and do it in my new (to me) boat. My boat is an 89 Bayliner 1950 Chevy engine.

Let me throw a disclaimer that I am not a certified marine mechanic and that I am not responsible for any damage that may occur to you, your boat and anyone else. This write up is for informational purposes only. Now, disclaimer aside get to work.

~You will need two quarts of gear oil suitable for your boat.
~A manual pump Attwood Gear Lube Pump: Automotive : Walmart.com .There are many out there but this one has a screw on attachment that made the fluid transfer a breeze with minimum spill. This one also screws on top of a quart of oil.
~Nylon washers for the three screws that you will be removing
~Oil catch pan
~your tools

First, you have get your personal protection equipment, and choke the wheels of your boat. Then, make sure that it is safe to lower your outdrive. Lower it and make sure that you can loose the TOP CENTER screw in the top of your outdrive. In this picture, you can see that there is another (top left) bolt loose but that is another story). If you are able to loosen it, leave it loose to allow fluid to drain.
2013-04-03_09-36-25_157-1.jpg


Now, proceed to to loose and remove the oil screw plug on the starboard side of your outdrive.
2013-04-03_09-36-56_292.jpg


After it drained, replace the nylon washer with a new one and screw it on tight...sorry, I do not have the torque numbers.

You are done with the first stage. Now, locate the MIDDLE screw and that is where OMC Cobras have to be filled in. Not from the bottom screw.
2013-04-03_09-37-00_775.jpg


Now, screw the gear pump to the quart of oil/fluid and pump slowly but steady. you will see that minimum air bubbles go in. Don't worry as long as you can fit the two quarts at the end and you check that the oil level is at an acceptable level.
2013-04-03_14-22-13_103.jpg

After you have pumped in the two quarts (or most of them). You must tight the top screw BEFORE you disconnect the pump from the outdrive to minimize the oil spill. Trust me, the air lock created by the top screw minimizes the spillage. Then you can disconnect the pump from the middle screw.

Last part, go back to the top screw and check the oil level. Most likely it needs more, so squeeze the left over from the two quarts and pour it in through that opening.

Recheck that all the screws that you loose and remove are tight, let the air bubbles work their way up the top overnight and check the oil level one more time before you start the engine.

Discard the used oil accordingly, clean up all the mess with an environmental mind, and you are done.

Happy boating,

That's it...
 

chrisrooter

Seaman Apprentice
Joined
Aug 11, 2012
Messages
41
Re: OMC Cobra 5.0 Gear Oil Change Tutorial with Pictures

Great reference, I am going to do mine in coming weeks. Hoping everything drains out with no surprises, bought bought used last year, 2.3L with cobra OD
image.jpg
 

papichuloy2k

Seaman Apprentice
Joined
Nov 8, 2012
Messages
42
Re: OMC Cobra 5.0 Gear Oil Change Tutorial with Pictures

Glad you found it useful. I found a few hiccups before the task, but that all that is in another post.
Good luck and happy boating...
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: OMC Cobra 5.0 Gear Oil Change Tutorial with Pictures

There is a tutorial up in the stickies at the top of the forum, has this from the OEM Service Manual.



attachment.php
 

wcasey5

Petty Officer 2nd Class
Joined
Feb 27, 2012
Messages
197
Re: OMC Cobra 5.0 Gear Oil Change Tutorial with Pictures

Great job! Where did you get the nylon washers?
 

Bulbash

Petty Officer 1st Class
Joined
May 22, 2012
Messages
332
Re: OMC Cobra 5.0 Gear Oil Change Tutorial with Pictures

Thank you good info!!
 

papichuloy2k

Seaman Apprentice
Joined
Nov 8, 2012
Messages
42
Re: OMC Cobra 5.0 Gear Oil Change Tutorial with Pictures

Great job! Where did you get the nylon washers?
I bought them at the local marine shop. They were slighty larger than the originals but theysaid that they will shrink to fit ..(I hope).
 

papichuloy2k

Seaman Apprentice
Joined
Nov 8, 2012
Messages
42
Re: OMC Cobra 5.0 Gear Oil Change Tutorial with Pictures

Thanks Don! I am new to the forums and my searching skill are poor but improving. I used the "search" feature and got very useful information but for some reason the "sticky" you posted didn't appear. But your post and the pictures I posted make a really good match right?
 
Last edited:

wcasey5

Petty Officer 2nd Class
Joined
Feb 27, 2012
Messages
197
Re: OMC Cobra 5.0 Gear Oil Change Tutorial with Pictures

I bought them at the local marine shop. They were slighty larger than the originals but theysaid that they will shrink to fit ..(I hope).

Cool. I like the homemade how to posts, give you a feel for how to do things. Great job!
 

papichuloy2k

Seaman Apprentice
Joined
Nov 8, 2012
Messages
42
Re: OMC Cobra 5.0 Gear Oil Change Tutorial with Pictures

I know, especially with the visual enhancements..(pictures). LOL.
 
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