Engine can not turn propeler after propler stuck in sand

[Gordon Gao]

I have a 1976 Mercury 7.5HP two strock outboard. The model is 75. A few days ago, the proper was stuck in sand while boating. After lifting the proper out of the sand, I found a piece of rock stuck between the proper and the metal above the propeler, stopping the propeler from turning. After the rock was freed out, the propeler can freely rotate back or forth while in neutral, and the propeler turns forward only while being shifted in forward gear, and turns backwards while in reverse gear. But when the enging is running, no matter in forward or reverse gear, the proper does not turn anymore. It appears that the engine can not engage to drive the shaft any more. <br /><br />Please help me out. My e-mail address is gaocanada@yahoo.com<br /><br />Gordon

 

[budblas]

Re: Engine can not turn propeler after propler stuck in sand

Sounds like the prop. did what it's supposed to do under that kind of stress: the hub has<br />broken free. That's the rubber 'cushion' between the prop. itself and the spline. If that <br />indeed is the problem, you can't fix it. Take it to a prop. shop.<br />Bud

 

[Fouled Plug]

Re: Engine can not turn propeler after propler stuck in sand

Yep, I'd bet it's the hub or shear pin. (Not sure what method your motor uses)

 

[Spidybot]

Re: Engine can not turn propeler after propler stuck in sand

This subject has been up a number of times as it happens every now and then.<br /><br />Make this simple test: Put a mark (scratch) on the prop shaft end and on the prop itself. Start and test the motor. Then check if the two marks have moved apart. If so the motor turns the shaft OK but the prop slips and the above description fits.<br /><br />Take the thing to a prop shop or look for a bargain on a new.. (link on this site).

 

[Gordon Gao]

Re: Engine can not turn propeler after propler stuck in sand

Re: propeller stuck in sand, a smal rock jamed between propeller and the metal above. Motor can not drive propeller anymore<br /><br />Thanks Bud, UU and Fouled Plug for the comments and advice.<br /><br />I took the propeller off and found the rubber sleeve is still good. The repair manual shows that there is no shear pin on the propeler shaft for this outboard (1976 Mercury 7.5HP, model 75).<br /><br />The engine can not drive the propeler no matter shifting in forward or reverse gear. Is there any serious damage? The motor runs so well. I hate to throw it away. Please help.<br /><br />Thanks<br /><br />Gordon

 

[Spidybot]

Re: Engine can not turn propeler after propler stuck in sand

At this point the question is if the gears in the lower unit died when hitting the ground.<br /><br />From your 'propeler turns forward only while being shifted in forward gear, and turns backwards while in reverse gear' I understood that the motor and gears were perfect?<br /><br />If the gear works, the prop shaft connects to the motor crankshaft and WILL be turned while running. If the prop/hub is OK the prop will turn.<br /><br />Merc's prop's do not use pins - the rubber hub is firm enough to keep it in place and at the same time serve as shock-protection when you hit a ground.<br /><br />Much more on props here if you like.

 

[DJ]

Re: Engine can not turn propeler after propler stuck in sand

Gordon,,<br />You say that the prop rubber hub is fine. How did you check it? Did you mark the prop. shaft and propeller outer housing (hub) as described?