Mercury 60 1988 outboard breaks loose

[daddybgood]

I just bought a boat with a merc 60 on it. I was running across the lake at top speed maybe for 5 min when she broke loose or wound out. I replaced the prop. Runs smoother still winds out at 1/4 to 1/2 speed everytime. What should I start out with to try and fix this problem. Please HELP! please HELP!

 

[daddybgood]

Re: Mercury 60 1988 outboard breaks loose

This is a 60hp engine 3 spark plugs, oil injected and I am not sure where to find the serial # if anyone needs it. I admit I am new at this but from 6 Years of Navy Engineroom experience I can turn a wrench and I am willing to try if someone can talk me through it I would be greatly appreciate it!

 

[whimsical]

Re: Mercury 60 1988 outboard breaks loose

It sounds like by "breaking loose" you mean cavitation. If the prop that you switched was fairly new then you can probably eliminate a spun hub. Either the engine is mounted too high or you have something on the boat bottom that is causing a disturbance in the water flow (thru-hull, transducer, etc.). Most modern props have some degree of cup built in but make sure that yours does. The only way to eliminate the possiblilty of a spun hub is to try a known good prop, or try your prop on a buddy's boat. Also make sure that you are not trimmed out too far either through power trim if you have it or the tilt pin away from the transom too much.

 

[daddybgood]

Re: Mercury 60 1988 outboard breaks loose

I took the boat out again today. And it does seem like the winding out or cavitation happens when the motor comes up onto the fin or hydrofoil. As long as I putt along I'm fine. Come up to speed on the foil and it winds out. Revs up real fast until I bring down the throttle. The boat does have power trim & tilt. I did put some fiberglass bondo right on the back at the dead bottom of the boat where it had a 3 to 4 inch tear and some up the center seam towards the front. But the boat ran fine after I did that for about a week. Then I was wide open sailing along for a good 5 minutes and she just wound out.

 

[daddybgood]

Re: Mercury 60 1988 outboard breaks loose

Thank you for your reply. Whimsical

 

[daddybgood]

Re: Mercury 60 1988 outboard breaks loose

Dear Whimsical, I just looked under the boat and low and behold I found that my patch has bent over on the front corner, and it looks as if this could be causing the cavitation problem. I have cut the corner off and sanded down the area. I am running over to our local pond with my fingers crossed I will let you know. THANK YOU

 

[daddybgood]

Re: Mercury 60 1988 outboard breaks loose

Whimsical you have made my weekend The boat is running great it seems as if I need to do a little better job with my patching. Any way she is running great and I really appreciate your help. THANK YOU AGAIN!!!!!!!!!!!!!!!!!!!!!!!!!!!!