1976 Mercury 85hp prop/rev Problems

[Mercrider]

:facepalm: this motor is new to me it has been sitting for 2 years when i got it I rebuilt the carbs and tried to hit the water it ran fine out of water idle and rev was good. when I took it to the lake I started out slow and then accelerated slowly. when I hit around 2000 rpm the motor started to free rev and would not go anymore like It would if I put it in to nutral but the prop was still spinning. I thought it was coming out of gear due to thottle cable adjustment but I put it in gear manually and held it wile we took off and it did the same thing. I was told that it was a bad prop but I just needed a second opinion. I took the prop off and visually inspected it, the splines are good and the rubber bushing looks decent I just dont know how the prop could cause this. I am new at this and I am out of Ideas. Thank you so much

 

[jestor68]

Re: 1976 Mercury 85hp prop/rev Problems

These props are equipped with a rubber "cushion" built into the propeller hub. It's purpose is to absorb shock when the prop hits an obstruction; helping to prevent damage to the lower unit.

Due to age or to a strike sometime in the past, the rubber hub has been damaged, causing it to "slip" under load.

I recommend a new Solas Amita aluminum prop ($105) to replace your worn out prop. Sometimes a prop shop can replace the damaged rubber hub, but I would keep that repaired one as a spare and just get a new one. The Solas will out perform your old Merc prop anyway; a 1976 design versus a 2012 design.

 

[Mercrider]

Re: 1976 Mercury 85hp prop/rev Problems

Thank you very much do you know what pitch I should go with

 

[jestor68]

Re: 1976 Mercury 85hp prop/rev Problems

Thank you very much do you know what pitch I should go with

What type/size boat is it on?

 

[Georgesalmon]

Re: 1976 Mercury 85hp prop/rev Problems

I'd guess the old prop had the correct pitch for your boat so get the new one the same. Look for the size undetr the prop nut.