Slipping out of gear

Status
Not open for further replies.

js407

Recruit
Joined
Feb 25, 2010
Messages
2
I have a 1969 starcraft with 120hp mercruiser I/O. While I was running up the lake the boat felt like it would come out of gear, and would rev up without going anywhere. I could go slow up the lake at about 2000-2500rpm with no problem. After fishing and running on and off slow all day, the boat operated just fine on the way back to the ramp. Any tips on what this may be?
 

Adirondack

Petty Officer 2nd Class
Joined
Aug 27, 2010
Messages
138
Re: Slipping out of gear

At first thought I would say a prop spinning on the hub, but the fact that later in the day it performed normaly leaves that in question. Did you physicly feel it come out of gear? I would think that at higher rpm if your drive came out of gear there would be a very noticable "clunk". If that's the case a simple cable adjustment could correct it.
 

js407

Recruit
Joined
Feb 25, 2010
Messages
2
Re: Slipping out of gear

I do not hear any clunk when this happens. When it does I will be cruising and just hear the boat start to spin, and see the rpm jump up. I can physically feel the boat slow down, and then sometimes you can feel it engage and the boat will take off again. It is strange that it stops after the day out and runs great on the way back. This is my first boat and I don't know much about them, so any help would be appreciated. Thanks.
 

dubs283

Vice Admiral
Joined
Jul 27, 2005
Messages
5,058
Re: Slipping out of gear

sounds like a slipping hub

try a new prop, good idea to have a spare
 

stonyloam

Vice Admiral
Joined
Mar 13, 2009
Messages
5,827
Re: Slipping out of gear

No clunk, happens intermittently, above certain RPM: I suspect prop cavitation, especially if you have a solid prop hub. Try a different prop.
 

wire2

Lieutenant Commander
Joined
Jun 25, 2007
Messages
1,584
Re: Slipping out of gear

My thought also, cavitation.

When it happens and the boat slows, let it drop off plane, then increase throttle. Does it continue to slip, or does it bite until you're fully planed, and then slip again?

Does turning left or right make the slipping worse?

Is your cavitation plate of the outdrive lined up with the bottom of the boat?
 

cr2k

Captain
Joined
Mar 19, 2009
Messages
3,730
Re: Slipping out of gear

lower you trim a little
 

Adirondack

Petty Officer 2nd Class
Joined
Aug 27, 2010
Messages
138
Re: Slipping out of gear

I agree. Could very well be cavitation.
 

FormaggioGrandi

Recruit
Joined
Sep 9, 2010
Messages
1
Re: Slipping out of gear

I am having the same problem on a 2003 5HP Mercury 2-Stroke.
I know its a small motor which should make pin pointing the problem easier however I'm still struggling. It doesn't seem at all that its slipping in the water. It definitely seems to be slipping somewhere internally. Usually when there is a good deal of torque on the prop or at high rpms it will slip and if I back of the throttle I can feel it kick back into gear. So if at full throttle with the prop engaged i do 15 it drops to 2 or 3 when it slips. I thought i may have been hitting bottom so i checked the depth and it was wayyyyy to deep. I tried spinning the prop with the motor off but in gear and it turns the motor. What baffles me is the fact that whatever this part is that is slipping hasn't blown apart yet. And that it goes back to normal when i back off.

This is a link to a better copy of the gear housing components
http://www.boats.net/parts/search/M...94439 & Up/Gear Housing Components/parts.html
 

Attachments

  • 5334.jpg
    5334.jpg
    11 KB · Views: 0

Reel Easy

Recruit
Joined
Sep 26, 2010
Messages
3
Re: Slipping out of gear

Just had this same problem yesterday 9/25. 115 HP Evinrude, 250HRs, Started to get-on plane, when half way out-of-the whole, the gear slipped and engine RPM excellerated very high, but no torque on the prop. Runs and spins prop at low RPM and hobbled back to the dock. Any troubleshooting ideas to check this problem out?
 

dubs283

Vice Admiral
Joined
Jul 27, 2005
Messages
5,058
Re: Slipping out of gear

Just had this same problem yesterday 9/25. 115 HP Evinrude, 250HRs, Started to get-on plane, when half way out-of-the whole, the gear slipped and engine RPM excellerated very high, but no torque on the prop. Runs and spins prop at low RPM and hobbled back to the dock. Any troubleshooting ideas to check this problem out?

yeah, start a new thread in the outboard forum
 
Status
Not open for further replies.
Top