Stern Drive problem

[GuinnessGuy74]

Yesterday, I had just changed the prop on my Alpha I Gen II. 5 mins later cruising around 3500 RPM, there was a loud bang. Engine would rev high with no movement. Though I had lost the prop but it was still there. No forward...no reverse. I know the drive is shifting by spinning the prop by hand. It is not the engine coupler since I can see the shaft spinning. When engaged in forward or reverse, nothing happens. Exactly as if I was in neutral. No noises either (metal scraping, gears grinding). Any thoughts as to what happened? Thanks for the info........<br /><br />Jim

 

[bomar76]

Re: Stern Drive problem

Spun hub in prop.<br />Mark hub and prop with a magic marker (ok, well there isn't really any magic in a marker) and run the prop in the water.<br />If the hub is spun, marks no longer line up.<br />Have prop rehubbed.

 

[GuinnessGuy74]

Re: Stern Drive problem

Thanks for the reply......If the hub is pun doesn't that mean I can turn the prop by hand when say in forward? Even at idle in forward/reverse the prop does not spin. Thanks for the help!

 

[bomar76]

Re: Stern Drive problem

Not neccesarily so....lot of difference in torque....

 

[Bt Doctur]

Re: Stern Drive problem

Couple of other ideas Define "drive is shifting by spinning the prop" it may be a hub. may still be the coupler.does it overheat? if shaft inside the boat turns ,the water pump may not due to a broken shaft.if it dosent overheat the shaft may be broken below the water pump.drive needs to be removed and shifted by hand to check further

 

[bomar76]

Re: Stern Drive problem

Any overheating?<br />A spun couple will not allow the lower unit impeller to pump water.

 

[neilmw]

Re: Stern Drive problem

I had this once with a big outboard, it would run fine until 2500rpm then it would just break loose and scream. but when you turn the prop by hand all gears seem fine. so it can be decieving

 

[neilmw]

Re: Stern Drive problem

Oh and I forgot to mention that this was a new prop!! sent it back, they confirmed it was spun and sent a new one which was fine

 

[imported_Mike_M2]

Re: Stern Drive problem

Possibly a broken u joint. Is it getting hot??? If it's staying cool the problem has to be in the lower unit as the pump is still working...