1985 omc 3.0l 400 outdrive not engaging

[TOPR8]

So the engine runs well but the prop won't engage in forward or reverse. The shift cables seem fine. When I shift into gear the prop gets resistance and if I turn it manually I can the outdrive gears turn and i can hear the impellers sucking fop fop fop sound. It just doesn't seem to be getting power from the engine at all. The shop can't get me in for three weeks... there is no odd sound coming form anything, no whining grinding or anything else that would imply damaged gears or anything I can think of. I had the outdrive fully down. Any ideas folks? It almost feels like it';s just not connected to the motor.

 

[Scott Danforth]

welcome aboard

on a stringer drive, the coupler is steel, so the chances of that are slim
the ball gears have a 400 hour life expectancy so those could have failed.
the lower shift cable is uber-expensive glorified bicycle cable and could be broken
most likely, the vertical drive shaft splines have failed (common problem)

 

[kenny nunez]

It appears that the water pump shaft splines are stripped where they engage the pinion shaft. To replace these parts unfortunately is not a job to try without the special tools to locate and protect the lower seals. These 2 shafts, a combination of stainless on the water pump and hardened steel with a chrome ring bonded to the seal surface on the pinion shaft is the weak link on the stringer drives. The older electric shift models this job was easier but the 400-800 models the job gets more complicated because of the hard mechanical shift cable which you do not want to damage. Hopefully the shop you are going to bring the boat to is aware of this. There is also a good chance you may have some water in the upper gear case due to the porus seal surface on the ball gear. Just loosen the lower drain screw on the upper gear case, if there is water that will be the first thing to come out. Hopefully not. I serviced OMC from 72-03 and replaced my share of these parts.

 

[TOPR8]

yeah not sure that's not it... a little inspection and I thing I've found the problem...

 

[southkogs]

That's the ball gears ...

 

[kenny nunez]

I hate to have to tell you the really bad news. When the drive was operated at a tilted angle and the ball gears actually “slip” over each other the force is like having a hydraulic jack between the intermediate and upper gear housing which causes the housings to distort. If you were to just replace the ball gears and run the drive in the full down position the ball gears will do the same thing and wear out in a very short time. I would not spend another penny on trying to repair the problem as both intermediate and upper gear housing need to be replaced. When I was a OMC dealer this was a very expensive repair, usually $1500.00- $2000.00 back in the late 80s.
If the engine is good, have the transom blanked and try to locate a later Volvo or Mercruiser drive line.

 

[kenny nunez]

Check out 70s OMC on the top of this page, I am sure he will want to hear from you.

 

[Redding Boater]

If I may add to this, if the ball gears were not engaging downstream from the intermediate housing, I would assume the impeller will need to be replaced.