Where to start on 3.0L OMC cobra repair

[bheston]

I purchased a boat with a 3.0L engine and OMC Cobra outdrive. The motor runs great, but the previous owner took out the lower unit, he said he was running forward at cruising speed and went to pull back to neutral and went too far and slipped into reverse, then it would growl when he put it in gear and wouldn't move. The boat sat for a year and then I bought it. I hooked it up to the garden hose and running in the yard the unit shifts into forward and reverse and the prop spins, but I'm guessing something must slip when there is pressure on the prop, I haven't dropped it into the water yet.

I'm going to tear the lower unit off and rebuild it myself, my question is where do I start? Is there an obvious place this may have failed or will I have to tear the whole unit apart to find a broken gear?

Thanks for the help, this forum is full of great information.

 

[gcboat]

Re: Where to start on 3.0L OMC cobra repair

I wouldn't do anything until she was put in the water and run. Then if all is still bad buy an OEM manual - no Clymer, no Seloc. Save those for mopping up spilled oil.
OEM manuals can be found on ebay.

 

[Bondo]

Re: Where to start on 3.0L OMC cobra repair

my question is where do I start?

Ayuh,....

Change the Oils,+ Splash it....... See what it'll do,....

 

[Lou C]

Re: Where to start on 3.0L OMC cobra repair

And if you do change the oil in the drive make sure you do it the right way, do a search for the procedure, most Cobras take 2 qts of gear oil.

 

[bheston]

Re: Where to start on 3.0L OMC cobra repair

I'm going to drop it in the water tomorrow and see what happens, depending on the outcome I'll probably drop the oil and see if it has any metal in it. Someone recommended replacing the prop as the rubber bushing might have slipped, is there any way to tell if a an aluminum prop has spun the rubber unless it is completely shot?

Also if I put the drive in gear and turn the prop by hand, I can turn the engine, so nothing seems to be slipping by hand. How much play should there be in the prop when the unit is in gear? It will spin about 20 degrees or so freely before coming against the gear.

Thanks again
Bob

 

[bheston]

Re: Where to start on 3.0L OMC cobra repair

OK so I put the boat in the water and it shifts into reverse and runs great, but it won't go into forward. When I shift into forward I can hear a light ticking sound like it is trying to engage. It isn't a grinding or hammering, just a light ticking when it is fully engaged in forward.

So when I pulled it out of the water and shut off I can put the shifter in forward and when I turn the prop it feels like it is fully engaged and tries to turn the motor over. Why doesn't it engage when it is running, what could be wrong???