cobra gear oil

[grizzreaper]

good day everyone. i got new crush gasket and a new seal for dip stick. drained the oil from drive. i put the bottom plug in and tightened. left top plug out and dip stick out. now i am not sure if the bottom plug is like any other drain plug, but i looked for any metal or crap on the plug it was ok. i went into the house to grab the oil pump to put the new oil in. my grandson who is 13 decided to help out his poppa n put a funnel in the dip stick and pour 32 ounces in there by the time i got back out the funnel was just about empty.now i am hoping this doesnt harm anything. i pumped about a good half or so of the second bottle in before it built up with back pressure n oil squirted back out. now my question is if i start the motor n put the drive in forward and then reverse and wait a few hours n put the reminder oil in. or do i have to drain the oil again and start over.

 

[jakedaawg]

I think your in the wrong forum but....I assume you are referring to an oMc cobra stern drive.

Remove dips tick , remove drain..Drain oil. Fill from bottom until proper level. You will not have filled properly going in from the top.

 

[jakedaawg]

The.issue with how you have done it is there will be air pockets trapped by the heavy gear oil that won't have been able to escape. The oil has to flow through small passages and it can't when put in from top. To be honest, I am surprised any oil actually made it in from the top with a funnel.

 

[bruceb58]

I think your in the wrong forum but....I assume you are referring to an oMc cobra stern drive.

Remove dips tick , remove drain..Drain oil. Fill from bottom until proper level. You will not have filled properly going in from the top.

On COBRAs, you fill from the middle...not the bottom. If you fill from the bottom, you will get air pockets and ruin your drive.

 

[jakedaawg]

On COBRAs, you fill from the middle...not the bottom. If you fill from the bottom, you will get air pockets and ruin your drive.

Is thus a joke? Or have I been missing something for twenty some years? Or maybe we are talking on the same thing and saying it different. I have drained and filled 30-50 of these a year since I can remember. The old stringers filled different but the cobras ...?

Not being a jerk. Willing to be educated.

 

[bruceb58]

No joke. You are lucky none of the Cobras you have filled improperly have not had an issue. Do a search and you will see how this has been an issue with many that have been filled improperly from the bottom.

Get an OMC Cobra service manual and this is what you will find. Fill port is the B plug

 

[jakedaawg]

Wow!!!

 

[jakedaawg]

No joke. You are lucky none of the Cobras you have filled improperly have not had an issue. Do a search and you will see how this has been an issue with many that have been filled improperly from the bottom.

Get an OMC Cobra service manual and this is what you will find. Fill port is the B plug

Guess I need to dig out those manuals.

 

[jakedaawg]

bruceb58 let me first say that i am.going under the assumption that you and the manual know more than me ....so, got the manual here. I guess I am.missing something because if I fill as stated the lower is only fed oil by gravity. The way we have done it, filling from the bottom, verifying oil level in spring has never failed. I am.wondering if the manual is a miss print. I can not fathom how the lower is getting oil without air trapped. If you are filling from the lower units vent hole oil will go down first, then you plug the drain and wait till you reach level on the dips tick. At least that's how I am reading it.

That doesnt.make sense.

Sorry for the periods every where. We don't have the net up here.and do all this over the phone. I really do and will value your response. Last thing I need is to have to buy some one an obsolete outdrive.

 

[bruceb58]

Yes, the bottom portion fills by gravity. There is no vent hole like there is on a Volvo SX. That hole is a fill hole.

After you drain, you put the drain screw back in followed by filling it from the middle hole until the oil reaches the dipstick hole.

If you do a search on here, you will find a few people that have suffered blown drives by filling from the bottom.

Also, always replace the gaskets/o-rings on all 3 plugs every time you change the gear oil.

 

[bruceb58]

Do a search on google with "omc cobra failed improperly filled" and you will find dozens of results that say the same thing
http://www.lmgtfy.com/?q=%22omc+cobr...erly+filled%22

Here is Dave Brown...a well known Cobra expert
http://www.brownsmarina.com/tech-winter-inboard.html

3. OMC Cobra 1986-1993 There is only one reservoir (the upper and lower gearcase share oil). There are, however, three screws. The drain screw is located in the *bullet* at the bottom, and the vent screws are located midway above the anti-ventilation plate and at the top center in the form of a dipstick. Pull the top and bottom screw to drain, but refilling requires that you install the bottom screw first, then fill the entire drive from the middle screw only until you get the proper reading on the top dipstick.
** FAILURE TO FOLLOW THIS FILL PROCEDURE WILL MOST CERTAINLY RESULT IN UPPER GEAR FAILURE. **
If the unit is filled incorrectly, an air pocket will form inside the drive such that when it *burps* up at a later date, will result in the upper oil level dropping thus destroying the top gears. Trust me on this as I have made quite a bit of money on people who were unaware of this procedure (they now leave their boat in my care ). Again, new gaskets are advisable on the screws.

Sounds like you dodged multiple bullets. I am assuming you are a marine center? Did anyone there go to OMC training when the Cobra was out?

BTW, I know a lot about the Cobra drive and I wouldn't let anyone touch it unless they had OMC training at some point. Besides the fill procedure, the lower shift cable also has a non straightforward procedure that changed over the years.

 

[bruceb58]

Another thing...gear oil is really no more viscous than engine oil. That's the reason certain Volvo drives used motor oil in their drives. 75w85 gear oil is almost the same viscosity as 30 engine oil.

 

[jakedaawg]

Do a search on google with "omc cobra failed improperly filled" and you will find dozens of results that say the same thing
http://www.lmgtfy.com/?q=%22omc+cobr...erly+filled%22

Here is Dave Brown...a well known Cobra expert
http://www.brownsmarina.com/tech-winter-inboard.html


Sounds like you dodged multiple bullets. I am assuming you are a marine center? Did anyone there go to OMC training when the Cobra was out?

BTW, I know a lot about the Cobra drive and I wouldn't let anyone touch it unless they had OMC training at some point. Besides the fill procedure, the lower shift cable also has a non straightforward procedure that changed over the years.

Yes, I certainly went to every class I could. Just must have missed or misunderstood this. Blows my mind actually. It has been .long time that we have done these and never had one fail so I wonder what we do different than the people that blow them. Maybe it's the sitting all winter and rechecking in the spring
before we put back into service that saves us.

Either way I have hijacked this thread for to long and I don't want to get scolded. Thanks for the heads up.

 

[bruceb58]

Maybe it's the sitting all winter and rechecking in the spring
before we put back into service that saves us.

More than likely that would be the key. Even when I filled mine properly, I would check it again in a few hours. I do the same with my Volvo SX drive that I currently own and I also check every time I launch my boat.

Fortunately, my OMC mechanic told me the proper way back in 1990 before the internet was around!

 

[grizzreaper]

ok so now that everyone has had say lol. do i drain the new oil out. do i run the drive in forward then reverse then wait and check the level again. everyones input was grt and yes i knew to fill from middle. lots of internet searchs and lots of you tube. so i want to take boat out this weekend but dont want to kill the outdrive

 

[grizzreaper]

and yes jakedaawg i did post this in the wrong forum. just realized that after i read your post.

 

[jakedaawg]

If it were mine I would drain and refill. Cheap peace of mind

 

[grizzreaper]

k i will open all the plugs and let it drain till fri. and then start over. thanks jakedaawg

 

[jakedaawg]

I think you could let it drain till it quits dripping then fill. No point leaving it open till Friday. That's just time for humidity to get in and plugs to get lost.

 

[grizzreaper]

should i try a lil compress air in there to see if there is any blockage.its been open since this afternoon. will look at in the am n see how much oil came out. thanks again for your help