OMC not shifting into gear.

dyno58

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Hello everyone! I have been lurking around this site for the last year and learning everything I can while working on my first boat 89' bayliner with 5.7 and OMC drive. I have learned alot, and honestly believe that many on here are very knowledgeable about boats. Now for my problem...

I went out two weeks ago and the boat was running fine for about 20min, then all of a sudden the engine free reved, and the boat competely stopped. I shut her down as the engine started reving high. Let the motor cool down and started her back up after visual inspection. Boat would not shift into forward or reverse. Had it towed back to the marina, and trailered her back home. Tried to put her in gear with the engine off and turn the prop, but it spins like its in neutral. The shifter was always very hard when shifting and figured my lower cable was bad or needed adjusting. Today I decided to remove the outdrive to inspect the transom cable. Everything looked really good, still had fresh grease from when the previous owner had overhauled the drive. Also it shifted very easily after I removed the drive. I tried shifting it using the shifter rod, but it only moves about half an inch. Seems like its a bit stuck. Could this be my problem? Also I checked the gear oil level and it was low. Then after a bit more research I realized that my uncle who owns a mercruiser helped me change my lower gear oil. We filled it from the bottom, big mistake from what I read. I removed the dip stick cover and the gears have no oil and some metal shavings. They have grease and they don't look so bad, but I also don't have a good set to reference to see how bad they really are. When I turn the u joint shaft the bearing spins, but doesn't make contact with the lower bearing. When I turn the prop the lower bearing spins, but doesnt make contact with the shaft bearing. Are they suppose to spin together even in neutral? Is the shifter rod suppose to be so stiff? Need to know if this is something I can fix or do I need to rebuild the whole drive. Please help, Thanks.
 

bruceb58

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Mar 5, 2006
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30,588
Re: OMC not shifting into gear.

Yep...huge mistake filling it from the bottom. Very likely that you underfilled your drive.

There are a few people on here that swear its ok to fill from the bottom on an OMC Cobra. It isn't as you are finding out.
 

dyno58

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Re: OMC not shifting into gear.

Is there any way the drive can be saved? I'm just wondering if the problem is the stuck shifter rod and not the shaft bearings. If the drive needs to be rebuilt, then I found one locally that I just might pick up. Please advise, thanks.
 

bruceb58

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Re: OMC not shifting into gear.

Would be guess on my part without being able to look at the drive.
 

a70eliminator

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Re: OMC not shifting into gear.

I'm pretty sure the shifting is done in the lower, do you have the upper seperated from the lower? If your looking in through the top cover of the upper you should see the main ring and pinion gears and they should both be turning with u-joint yoke.
The shift rod is kinda tough to actuate by finger grip, the detent springs are strong.
Filling from the bottom isn't all that bad as long as you get it filled all the way up to the dipstick, my guess is your uncle only filled it to the center hole which left the ring and pinion dry.
 

dyno58

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Re: OMC not shifting into gear.

Yeah when I turn the input shaft the bearings don't make contact. If I spin the prop the lower bearing spins, but they do not spin together. So just to confirm if I spin the input shaft while looking inside the top cover I should see both gears turning? How come the pinion gear spin when I turn the prop? Is it because its stuck in gear? Sorry for my ignorance, just trying to understand exactly how it works and what the problem is. Thanks.
 

a70eliminator

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Re: OMC not shifting into gear.

The gears in the upper are turning 100% all the time when the engine is running or when you turn the input shaft, then the intermediate driveshaft connects to the lower gears, it also is turning with the engine and upper gears, in the lower torpedo is where the prop engagement happens forward and reverse gears. Your loosing me when you speak of bearing making contact, not sure what your describing.
Both gears in the upper HAVE to turn or something is broke, like a section of missing teeth maybe.
 

dyno58

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Re: OMC not shifting into gear.

When looking down with the upper cover removed there is a gear attached to the input shaft and another gear going down to the lower. When I turn the input shaft it does not make contact with the gear leading down to the lower, but from what your telling me they should be turning at all times. So I'm guessing something is broken or teeth are missing from the gears running without oil. Also when I turn the prop looking down in through the upper I can see the gear going to the lower turning. Does this mean the the prop is in gear?

I hope I am making sense. When I said bearing I really meant gears, sorry.
 

a70eliminator

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Re: OMC not shifting into gear.

Sounds like your in gear, thats why the pinion gear moves with the prop, the reason why it seemed like you were in neutral when it happenened is because the ring gear is no longer meshing the pinion for reasons unknown at this point, you'll just have to start diesecting the upper.
 

dyno58

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Re: OMC not shifting into gear.

Thats exactly what I wanted to know. I wanted to rule out the the stiff shift rod as the main problem. Sounds like the upper gears are toast. I am going to look at a used drive this weekend, so I just wanted to know exactly what to look for. Thanks for the help so far.
 

bruceb58

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Re: OMC not shifting into gear.

All shifting is done in the lower at the dog gears.

You never ever fill from the bottom. An air pocket can form on these and it will appear that you have it filled to the dipstick on the top of the housing until the air pocket "burps" and you are now low on fluid and have the problem with the top gears failing.
 

dyno58

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Re: OMC not shifting into gear.

Trust me that will never happen again. I read the procedure about four times just so I knew how bad I messed up. From now on I will start the motor then recheck the dip stick.
 

bruceb58

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Re: OMC not shifting into gear.

Everytime I take my boat out, I check the drive oil level, the engine oil level, start the boat and make sure its cooling properly...
 

dyno58

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Re: OMC not shifting into gear.

I check the engine oil and temp. I would only do a visual of the outdrive. From now on it gets a 50 point inspection:). Hopefully the used outdrive I'm going to see is in good shape and I can get back out on the water.
 

shimano

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Jul 26, 2008
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Re: OMC not shifting into gear.

Can you fill from the bottom as long as you put the required 1900cc in?
 

bruceb58

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Re: OMC not shifting into gear.

Can you fill from the bottom as long as you put the required 1900cc in?
You can fill it anyway you want I guess. Either the way the manual states to do it or any other way and take your chances...your choice. Me...I always did it according to the manual.
 

sea wolf

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Re: OMC not shifting into gear.

Can you fill from the bottom as long as you put the required 1900cc in?
Look, if it's an OMC Cobra, you fill it from the middle plug. Period. Screw around & fill it any other way & you'll be sorry. Cabeesh?
 

wire2

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Re: OMC not shifting into gear.

...
You never ever fill from the bottom. An air pocket can form on these and it will appear that you have it filled to the dipstick on the top of the housing until the air pocket "burps" and you are now low on fluid and have the problem with the top gears failing.
Is this the rule on OMC Cobras only? Or all marine gear cases? I was under the impression that the rule was to not fill from the top to avoid the oil flooding over an air pocket and remain trapped. The illustration on the bottle pump & nylon fitting kit I have describes bottom filling.

I had an 800 stringer, now have an Alpha, btw...
 

nola mike

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Re: OMC not shifting into gear.

Is this the rule on OMC Cobras only? Or all marine gear cases? I was under the impression that the rule was to not fill from the top to avoid the oil flooding over an air pocket and remain trapped. The illustration on the bottle pump & nylon fitting kit I have describes bottom filling.

I had an 800 stringer, now have an Alpha, btw...
we're talking about cobras.
 

shimano

Petty Officer 2nd Class
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Jul 26, 2008
Messages
141
Re: OMC not shifting into gear.

The foolproof way is to fill it as per the manual.I have always filled mine ,from the bottom adding the amount recomended in the manual,Check the dipstick and it is perfect.It can give you false readings if your relying only on the dipstick for reference.Put in the recommended amount(probably from any hole ya want)and you can't go wrong.
 
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