1979 merc 50hp wont rev when in water

[mercmarc1979]

hi there i recently bought a 1979 mercury 50 hp 4 cylender outboard,when i test it in a barrel of water it seems fine and revs up and throws all the water out but when i put it on my 15 foot dateline speedboat and put it into drive it wont rev and only just moves the boat in no more.i checked to make sure it was getting full throttle at the engine by working the lever by hand but with no success,could this be a prop problem or is there anything else i should check thanks in advance marc..

 

[mercmarc1979]

Re: 1979 merc 50hp wont rev when in water

hi there i recently bought a 1979 mercury 50 hp 4 cylender outboard,when i test it in a barrel of water it seems fine and revs up and throws all the water out but when i put it on my 15 foot dateline speedboat and put it into drive it wont rev and only just moves the boat in no more.i checked to make sure it was getting full throttle at the engine by working the lever by hand but with no success,could this be a prop problem or is there anything else i should check thanks in advance marc..

i also forgot to mention that the first time i put it on my boat i forgot to bolt the transom bracket to the boat and it fell off into the water i jumped in and got it out within aprox 30 seconds can this have caused this and ifso what shall i do? thanks again

 

[RyanSS]

Re: 1979 merc 50hp wont rev when in water

wait...wait...wait....what fell in the water? The motor?! Or the bracket?

 

[mercmarc1979]

Re: 1979 merc 50hp wont rev when in water

hi there it was the motor that fell in the wTER BUT I GOT IT RUNNING AGAIN,LIKE I SAID WHEN IN A BARElL OF WATER IT REVS UP AND THROWS ALL THE WATER OUT OF THE BARREL BUT WHEN ITS ON MY BOAT IT JUST BARELY MOVES IT

 

[mercmarc1979]

Re: 1979 merc 50hp wont rev when in water

can anyone plz help as im planning on running boAT ON SUNDAY THAnkyou

 

[James R]

Re: 1979 merc 50hp wont rev when in water

Do the RPMs come up ok and the boat still does not move. If this is the case then you dont have it in gear or the prop core is Kaput.

 

[James R]

Re: 1979 merc 50hp wont rev when in water

Sorry, you said it wont rev. Are you sure that the prop is turning in the tub or is it just the exhaust that is pushing the water out. Could be that the lower unit is locked up when you get it into gear.

 

[mercmarc1979]

Re: 1979 merc 50hp wont rev when in water

when i run it in neutral in a barrel it pumps fine then when i put it into gear the water goes crazy and when i rev it it throws it out so i just assumed the prop is turning.what can i do to check if its like wot you said about being locked up.the boat does drive but only at about 3mph or so very slow.any help is much apreciated

 

[catcatcher]

Re: 1979 merc 50hp wont rev when in water

Sounds like a spun prop to me. When in the barrel it doesn't have the preasure of the boat on it thus making it spin without slipping. Take the prop off and inspect the hub You will be able to tell if it is spun.

 

[mercmarc1979]

Re: 1979 merc 50hp wont rev when in water

thanks for the info guys but i think ive found the problem,there is a hole in bottom end of engine on cylender 4 looks like the big ends have broken out do you reckon this is worth fixing?

 

[DRIFTER_016]

Re: 1979 merc 50hp wont rev when in water

Ummmmm Yeahhhhh
Holes in the engine block are never a good thing.
You couls search around for another power head for it, but it might be easier to just replace the whole thing.