forward gear problem

[nekot1]

I have a 1971 merc 110 serial# 3005756. I was out on the lake today and it ran just fine. I was on my back in and it just start winding out, as if it was in neutral. I slowed down and it ran fine again,then as i turned the throttle about a 1/4 of a turn it would wind out again. Could the forward gear be stripped or maybe something else?

 

[Motor Boater Bill]

Re: forward gear problem

Sounds like the prop hub is spun. The hub is the splined part that fits with the splines on the prop shaft. There is a rubber bushing between the hub and the prop that acts as a shock absorber.<br /><br />Mark the hub and the prop and get it to "wind out" and see if the hub has moved. If so, you will need to have the prop re-hubbed, cost $35-$50, or get a new prop (sometimes cheaper than a rehub on eBay). Just make sure you don't buy another one that is spun.<br /><br />If your gears were shot it would probably make some very ugly noises. Trust me, I have heard these noises...

 

[brad needs help]

Re: forward gear problem

im not sure what your problem is but i have a 60hp merc and today it did the same thing to me, i thought i spun the hub in my prop so i changed it and it still does it, i am going to take it apart and i will let you know what i find

 

[Motor Boater Bill]

Re: forward gear problem

Brad, the other likely cause, if you are sure the prop is not spun, is cavitation. Also, make sure you don't have 2 spun props. Marking the hub will tell you for sure. If your lower unit is shot it won't likely "run fine" at idle and slip at higher throttle settings, particularly without making bad sounds in the gearcase.<br /><br />There are many causes for cavitation (or more properly, ventilation). I had a problem with this on a 20 hp Merc and found that the middle stud hole one the lower unit was broken out in the casting, and exhaust was getting into the prop slipstream. Acted just like a spun prop. Prop has to grab solid water to push the boat.

 

[Texasmark]

Re: forward gear problem

Hey Bill, that'll do her if nothing else will....exhaust in the slipstream. Exactly what "vented" props do to spin her up.<br /><br />Mark

 

[brad needs help]

Re: forward gear problem

ill look but the boat did just fine befor i have 3 prop for the boat and i want and put the third one on it still does it so i will check every thing else out thank you for the info.