Spun prop or striped gears

dszjlane

Cadet
Joined
Apr 11, 2005
Messages
25
Hey All<br /><br />Just as you start to gain confidence in your motor, S*&% happens!!! 1966 650 Merc<br /><br />Had myboat out onthe weekend ( Family camping trip)finally convinced my skeptical wife that the motor wasworking great(and it had been) SO we all went fishing the motor worked marvelously going up the lake, it was were ready to try another fishing spot that things went horribly wrong. startedthe motor and put it in gear,heard a loud grinding noise but the boat started togo forward so I began to accelerate,as the boatbeganto plane out it all of a sudden began to slow down but the enging began to over rev. We were able to slowly make it back to the boat launch under our own power but only with the enginge idleing. As soon as I would accelerate it would do the same thing.Iinitial thought was that the lower unit was striped out ( Had lower unit serviced last year at a merc dealer he said the gears were worn considerably),but now I wondering if the prop has spun out. Is there a way you can tell by inspecting the prop???
 

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: Spun prop or striped gears

A spun prop don't make grinding sounds, did rev. work, if it did the problem could be adjustment
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: Spun prop or striped gears

Could the "grinding noise" have been the prop trying to chop rocks?
 

mercuryblues

Seaman Apprentice
Joined
May 9, 2003
Messages
37
Re: Spun prop or striped gears

You can take your prop off and have the motor in gear and see if the prop shaft is also in gear or not.I have had props rehubbed for around 40 bucks apiece ask at a marina if they do it,hope this helps.
 

dszjlane

Cadet
Joined
Apr 11, 2005
Messages
25
Re: Spun prop or striped gears

Didn't try reverse didn't want to put too much strain on the gears as were about 10km's from boat launch. I know it wasn't rocks as we were in about 20 feet of water. my friend has a spare prop for his 850 merc I'mgonna give thata try later today. Also he has a spare lower unit for his engine its a 1975 850 merc anyone know if this wouldfit my engine, and if so would the gear ratio be different.
 

AndyL

Petty Officer 1st Class
Joined
Jul 1, 2002
Messages
307
Re: Spun prop or striped gears

Have you tried marking the propshaft and hub with a line of paint then running it. If the lines mis align then it sounds like the hub has spun. Hope its not yours gears>
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: Spun prop or striped gears

Check your lower unit oil - if it's spun the gears out there will be LOTS of metal filings and likely even chunks in the oil...<br />- Scott
 
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