new problem

[saultguy]

so got the shifting issue down, it was a bad connection at the transom, put the boat back in the water, and when i put it in gear there is a horrible whirring noise and no prop movement, with both forward and reverse in neutral its fine...any ideas? thanks in advance

 

[GA_Boater]

What OMC I/O is whirring?

 

[saultguy]

it s '73 120hp omc i/o, whirring is hte best i can describe it....when the engine is off and key "on" and in forward it is prop doesnt spin free, same with reverse, neutral it spins fine

 

[GA_Boater]

A Stringer - Check the ball gear.

 

[saultguy]

visually the ball gear looks ok, the nubs are worn for sure, but not anywhere near as much that wouldnt engage

 

[GA_Boater]

Sure you got the electro-shift working?

 

[Scott Danforth]

If the "nubs" as you called them on the ball gears are worn more than 25%, you need new ball gears

 

[saultguy]

is there something in the shifting that would cause this, you can feel it engage when you shift it and it is "locking" the prop when in gear with the engine off, and the sound goes away when in neutral

 

[saultguy]

no, not nearly that much, maybe 10%

 

[Grub54891]

Check all the gearcases, make sure they are full of the proper oil.

 

[saultguy]

when i had it at the mechanic he verified that he used c type oil in the lower end...and changed all the fluids

 

[southkogs]

You might be able to hear a "clink" when the gears engage to F or R, but you shouldn't hear any noise otherwise in normal operation.

Stern drive is tilted full down, correct?

What about the drive shaft in the upper gear case? Those are known to strip kinda' easy. Maybe it's spinning fine until you put it under load, and then it's just grinding away.

 

[kenny nunez]

Most probably the water pump shaft male end where it plugs into the lower female end of the pinion shaft is the source of the noise. The water pump shaft is stainless and the pinion shaft is plain steel. The parts are still available from Sierra but some special tools are needed to set the torque and locate the seals at the correct depth. I still have the tools from when I had my shop. After 72 Most 120 hp drives were the “low profile” style and were 4” shorter than the 72 and earlier.

 

[saultguy]

taking it back to the mechanic tomorrow, it definetly sounded like it was above the water level, just the amount of noise sounded like its from the top end....

 

[southkogs]

If you're not tilted fully down, the ball gears can make an awful grinding noise. If that shaft is stripping (Kenny's description is better than mine), I would think you could hear that too.