50hp merc "slips out of gear" over 2000 rpm

taraj

Cadet
Joined
Jul 24, 2005
Messages
9
Just bought my first boat. Took it to get serviced so it would run perfectly first time out but that didn't seem to work. At first it worked fine, then decided to "bog out" when giving it more power. Later that day it worked great for an hour or so until towing the final tube ride, going close to top speed and it suddenly seemed to kick out of gear and rev like crazy without going anywhere. Now it "revs out" at anything above 2000rpm. Someone just told me that since it just got serviced that if they didn't fill the oil from the bottom it could have had air trapped inside which would have messed with a bering.... I know nothing about motors but would like to have some ideas of possible problems before going back to the mechanic, just incase it was something they screwed up. It's a 50hp Merc 500, not sure of the year but late 70's to early 80's probably. 3 tone blue stripes with white merc lettering. Any ideas?
 

saltykracker

Cadet
Joined
Jul 12, 2005
Messages
29
Re: 50hp merc "slips out of gear" over 2000 rpm

sounds like the hub on your propeller is slipping. A common problem, bring it to your local prop shop.
 

AMD Rules

Lieutenant Commander
Joined
Sep 23, 2004
Messages
1,707
Re: 50hp merc "slips out of gear" over 2000 rpm

Is the motor trimmed down all the way? Anti-ventilation plate even with the bottom of the hull? Anything on the hull that may impede smooth water flow to the prop?<br /><br />You may have a spun prop hub. The inner rubber portion fails over time, or if you strike a submerged object. Mark a line across the center of the prop and the outer housing. If they don't line up after you run the boat on the water you have a spun hub. Easily repairable at a local prop shop or marine service shop.
 

taraj

Cadet
Joined
Jul 24, 2005
Messages
9
Re: 50hp merc "slips out of gear" over 2000 rpm

Thanks for the advice!! I'll get the prop hub checked.
 

timmathis

Lieutenant
Joined
Apr 24, 2005
Messages
1,295
Re: 50hp merc "slips out of gear" over 2000 rpm

Go to oldmercs.com and you can find out what year it is.
 

KIGuy52

Petty Officer 1st Class
Joined
Jul 22, 2005
Messages
210
Re: 50hp merc "slips out of gear" over 2000 rpm

Merc 500's rock!
 

taraj

Cadet
Joined
Jul 24, 2005
Messages
9
Re: 50hp merc "slips out of gear" over 2000 rpm

Thanks for all of your ideas... Yes, as it turns out, my "new" used prop I bought was no good. It was spinning on itself when going over 2000rpm. When I took it off there was a mass of rubber goo inside it just laying there. I am going with a NEW prop this time, so hopefully it will work well for a very long time!
 
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