Spun Prop or lower unit issue?

I have a 1984 Mercury 50 horse, had it on the lake just came up on plane heard a loud metal ping and have no power to the prop over idle speed, reverse still works fine. Several people suggested checking for a spun prop. The hub in my prop is welded in place with no rubber around it, pulled the prop and none of the splines show any sign of damage.
While checking the prop it was realized that the prop can be turned clockwise with little resistance while in gear. Should this be possible or is it an indication of a problem in the lower unit besides a spun prop??

Any suggestions would be greatly appreciated.

Re: Spun Prop or lower unit issue?

vrooman13 said:

I have a 1984 Mercury 50 horse, had it on the lake just came up on plane heard a loud metal ping and have no power to the prop over idle speed, reverse still works fine. Several people suggested checking for a spun prop. The hub in my prop is welded in place with no rubber around it, pulled the prop and none of the splines show any sign of damage.
While checking the prop it was realized that the prop can be turned clockwise with little resistance while in gear. Should this be possible or is it an indication of a problem in the lower unit besides a spun prop??

Any suggestions would be greatly appreciated.

Click to expand...

LU's broken. It should ratchet when you turn the prop by hand in forward gear.

Re: Spun Prop or lower unit issue?

It does rachet when turned clockwise and it will not turn counter clockwise when in forward gear.

Re: Spun Prop or lower unit issue?

vrooman13- I am having the same issue with m Merc 140, thought I'd chime in. I originally thought it was a stretched cable or control box issue (perhaps it wasn't "fully": in gear), so I went ahead and spent $200 on new cables and control lever- that didn't fix it.
Also put a new prop bushing (plastic), since the old one had a crack in it- didn't help either.
My symptoms were the same: Reverse and neutral work fine, but forward did no. There is a slight grinding sound as well when throttling in forward.
The funny thing is that when it is out of the water forward spins "normally", does yours?
As for the ratcheting clockwise, mine does as well..the only problem is that it locks as it should CCW, but if you turn hard enough it does "click" and turn CCW. You say yours won't turn CCW, how much force were you applying?

Anyways, the moral of the story is:
I eventually broke down and brought my boat to the shop the other day, they told me it needs a new lower unit Although they have not torn into it yet, they took off the cables, hand shifted and came up with this diagnosis. The cost for a working used lower unit, including installation: $500.
That's more than half of what I paid for the boat!
The shop tells me that my forward gear and possibly my clutch dog are gone,and they don't normally rebuild units there. I was going to find one on my own for around $300 , but I have never put one before and don't really have the time now. When they swap mine out, at least I will have my old one to "practice" on, maybe even rebuild/resell to recoup some of my costs. It can't be that hard, and I am pretty good with a wrench.

SO in conclusion....I concur with j_martin, sounds like the lower unit---sorry.