checking OMC outdrive gear lube

[VMAX]

Hi all, I've got a question concerning the maintenance of my OMC Cobra outdrive. According to the manual that I have, the gear lube is checked by a dipstick on the top of the housing.<br />There are 2 plugs on the lower part of the drive, one for draining, and one higher up, supposedly for filling. My experience is with outboards, draining AND filling is done through the lowest plug, and the upper one is just to check the level. My question is, do I fill from the bottom up, or from the higher plug? I'm afraid of an air pocket in the lower unit, since I work with a guy who destroyed his lower unit this way. Any help would be appreciated.

 

[snapperbait]

Re: checking OMC outdrive gear lube

Same proceedure as an outboard....Bottom's up..

 

[dick]

Re: checking OMC outdrive gear lube

After the oil is drained put the bottom plug in then fill the case at the plug in the middle. No debate ,this is the way it is done because it rules out trapping any air in the drive.If you have a manual it will say the same thing.

 

[Dhadley]

Re: checking OMC outdrive gear lube

Ditto. Cobras are filled from the middle. And check it after you run it a few minutes.<br /><br />Good luck!

 

[nightride]

Re: checking OMC outdrive gear lube

also check the gear oil on the top housing you will see a screw on the top that must also be full your you will ruin the top gears

 

[VMAX]

Re: checking OMC outdrive gear lube

After further investigatin I was able to determine that there are two separate housings that have to be filled. The manual that I have is a CLYMER and it seems to be full of errors. It explains the drain/refill procedure by telling you to drain fluid from the bottom of the lower unit,(pictured in a photo of the lower unit), refill from the top of the lower unit,(also shown in the photo), and check the level from the dipstick on the top of the upper gearcase. I assume that you can fill the top of the lower unit 'til the cows come home and never affect the dipstick reading. Also, when you drain the lower unit and try to refill it from the top, you will probably trap air in the lower unit, and when you check the dipstick in the separate upper gearcase per the manual, it will read full, since it's never been drained in the first place. Time to buy a new manual.

 

[sea wolf]

Re: checking OMC outdrive gear lube

cobra's are filled from the bottom. if you're not sure how much it takes check a manuel to get an idea or ask a cobra dealer. if u fill from the top u will get air pockets. when your filling take your time, don't pump it in too fast. when you're done filling, let the unit sit overnite to let the oil drain past all the seals, then check it again. make sure u don't overfill! to eliminate possible air pockets, start the engine, put it in gear {with the prop off of course} & let it run for a couple minutes, then check the level again. here's a tip. if u overfill it, use an antifreeze tester with the plastic hose on the end to suck out the excess through the dipstick hole. it's ok to top off the unit from the dipstick hole, but not to fill the whole unit.

 

[P.V.]

Re: checking OMC outdrive gear lube

Ok, here IS the reason you must/should fill the drive from the middle. A Cobra drive uses a outboard gearcase housing.SAves money by utilizing one gearcase vs. making two. Just aft of the shift shaft cavity, there is a protrusion inside that effectivly creates an air pocket and traps air. On an outboard this is not a problem but on the Cobra, the oil must travel up to fill the upper gearcase to the proper level. The oil will go up into the upper if filled from the bottom but the pocket of air remains. By filling from the middle hole, oil goes down into the forward pocket and back up and eliminates the air pocket. What will happen if not done correctly is that the air pocket WILL migrate soon after running and now the upper gear oil level is too low. The small rear horizontal shaft bearing in the upper will burn up!!!!!! <br />IF, and this may get confusing, IF, you fill the drive fromm the bottm AND leave the middle plug out untill oil comes out of the middle, you could fill from the bottom.That way you would allow the air to escape From that shift shaft cavity. BUT only if you do it that way. So really, everyone is instructed to do the middle thing and avoid confusion. When ever someone comes in with outdrive problems I always ask if they filled the drive correctly, From the bottom, right?? Of,course, they say. Now I now if they screwed it up themselves.

 

[Boatin Bob]

Re: checking OMC outdrive gear lube

There is no debate, you drain from the very bottom and fill from the middle until it comes out the top where the dipstick is as several others have said and the reasons for it. I also check it again in the spring just incase. The original OMC service manual I have says this but the others leave a bit to be desired. Have included the link for Stuarts site, as some of you know he has piut together a very good document on Cobra's, mostly to with shifting problems however if you look on his hints page, second item down talks about filling lower unit. Stuart's Cobra web page

 

[Dually Driver]

Re: checking OMC outdrive gear lube

If you want to see what the two upper gears look like when this is done incorrectly, e-mail me and I'll send you a picture.<br />Mike

 

[VMAX]

Re: checking OMC outdrive gear lube

Thanks to all who have helped. Here is the reason for my confusion: There appear to be 4 plugs total; 2 on the upper unit and two on the lower unit. Correct me if this is wrong, but doesn't the upper unit have to be filled by the plug on the bottom of the upper unit? (second plug from the top, about 4 inches down, same size as the top plug with the dipstick?) and checked by the dipstick on top? Doesn't the lower unit get filled from the smaller plug at the bottom of the lower unit? 4th plug down from the top, smaller than the top 2 plugs, and checked from the top of the lower unit? (3rd plug from the top, same size as the bottom plug? Remember that I stated that the CLYMER manual shows only filling at one point,the top of the lower unit, and checking at one place, the top of the upper unit.<br />I will check the link and see if I can understand this better.<br />Thanks, John

 

[P.V.]

Re: checking OMC outdrive gear lube

There are three oil fill/drain plugs on a Cobra. Not four. Located at the very tip top(has a level guage built in to it.Middle (or top of the lower unit) on the starboard side and lower on the bottom of the lower unit just below the "bullet" on the atarboard side. That's it!!! If you are also referring to a Plug on the port side of the upper gearcase, then do not remove that plug. It WAS cover'd up by a decal early on in life and is a water passage. If you do remove it, then the internal hardware, washer,o-rings and nut will fall off. You will then have to remove the outdrive to reinstall that stuff. Pleased note, a Cobra has one oil cavity only unlike the earlier OMC stringers that had a upper and seperate lower.

 

[Boatist]

Re: checking OMC outdrive gear lube

VMAX<br />Are you sure it is a Cobra or could it be a series 400 or series 800 stringer??<br />Does it have hrdrolic cylinder on each side to raise out drive or a big gear??<br />What year is it??<br />What color is it??

 

[sea wolf]

Re: checking OMC outdrive gear lube

just to clarify. cobras are filled from the middle plug. i don.t think u can screw the fitting into the bottom plug, which is the drain. i guess i asssumed folks would know this. i should have said middle, so as not to confuse anyone. also, there's another plug on the port side. that's a drain for the water pump. when your winterizing, don't forget to remove this plug to drain the water.

 

[VMAX]

Re: checking OMC outdrive gear lube

Thanks again for all the replys. I was indeed confused by the plug on the port side of the upper unit. The drive is definately a COBRA, and I will attempt to fill it from the upper plug on the lower unit. The only thing which seems odd to me is that an air pocket doesn't form in the lower unit. It also seems as though it would take an awful lot of fluid to fill the whole thing up to the top, but if there's only one chamber it makes a lot more sense.<br />John

 

[thomose]

Re: checking OMC outdrive gear lube

Just a F.Y.I. concerning your Cobra, I went through the same questions last year when I became new to boating. One thing to keep in mind is your outdrive should take just under 2 quarts of fluid to fill the upper & lower combined. Maybe this will help.(approx. 62oz.) T.K.

 

[Boatin Bob]

Re: checking OMC outdrive gear lube

Thomose...that's a good point for most Cobra's unless you have the 7.5 (460) like me which is a little larger and takes 108 oz.

 

[thomose]

Re: checking OMC outdrive gear lube

Boatin Bob, thanks for the reply -- my apology, I meant to mention in my post that mine's a 3.0L 140HP. (I guess these details are important!)TK

 

[VMAX]

Re: checking OMC outdrive gear lube

While we're on the subject, My boat is a 1986 3.0 liter, but I'm only assuming that it's 140 horsepower. I don't know how to tell what the horsepower rating is. Are all 3.0s 140 horse?<br />John