50HP merc appears to be popping out of gear

[benningtonr]

Last night we took some neighbors out on our 18' Fisher pontoon boat. While at full throttle three or four time it appeared to pop out of gear, and the RPM's shot way up. I immediately pulled the throttle back and then when the RPM?s were just about to reach idle I would go forward a little and it was still in gear. This is the first time this has happened, any ideas as to what it might be? It shifts in and out of gear fine both forward and reverse. We cruise the rest of the night at ? throttle and all was fine. At one point I has to make an immediate right turn to avoid a log, and it popped out of gear, even at the lower throttle setting.


Thanks or any and all input

 

[GA_Boater]

You may have a spun prop hub. Using a marker, draw a line across the hub and prop. If the line isn't straight after having the drop out of gear symptom, the hub has spun.

 

[benningtonr]

I read a lot about spun hubs. Most of the folks this happened to were not able to go more than a little throttle. Due to my motor only being a 50HP is that the reason I can go full throttle and then back it down to 3/4 and it runs fine? Then it will just loose bite or spin the motor rpm's way up out of the blue. Then after dropping throttle back to idle and the forward again it resumes normal activity.

Trust me I hope it is a spun hub, I have a spare, just looking at all the angles.

Thank again for your help.

 

[GA_Boater]

I also have a 50 HP Merc and the hub spun. It got progressively worse to where the max RPM was about 1500 before spinning. Problem was I had to go about 10 miles back to the dock. It was a slow trip and got slower the closer I got.

Do the line trick or swap in the other prop.

 

[benningtonr]

is there anyway you can call me 757-889-9484?

 

[GA_Boater]

is there anyway you can call me 757-889-9484?

Nope

 

[benningtonr]

okay no worries, i will swap them out and go from there. Thanks again

 

[MH Hawker]

i would bet its a spun hub

 

[benningtonr]

Took the prop to a local shop, and the hub is fine, still popping out of gear. So that mean it has to be in the shaft or transmission, correct? Also i read that if the transmission was the culprit, it would make a lot of noise. No noise or rattling, just the RPM's sky rocket until i back it down, then it starts motoring along again, without having to go to neutral.

 

[roscoe]

Have you tried a different/new prop?
There is no way it is going in and out of gear with the engine at speed- without making some noise.

 

[benningtonr]

I have not tried another prop yet, the only noise I hear when it does this is the rapids rise in ROM as if it were in nuetral. I will pull the throttle back and when it gets to 12-1500RPM I can feel the boat start to move again, I can feel the prop. pushing me forward.

 

[GA_Boater]

Have you tried a different/new prop?
There is no way it is going in and out of gear with the engine at speed- without making some noise.

Agreed. The prop spun on my 50 and it wouldn't go more than 25-3000 RPM at first and before I got back to the ramp, the most I could get was 1-1500 RPM. That was a slow 8 mile return trip.

Have you tried drawing a line across the hub and checking that it is still lined up after the slippage. The rubber in the hub looked perfect. How did the shop check the hub, any idea?

 

[benningtonr]

I am not sure how he checked it, he took it into the shop, came back 15-20 min later and said it was fine. He did not charge me anything or try to sell me anything. I will mark it next time we take it out, probably in April or may. I can easy up to 3-3.5k and run all day. It pops out if I make a sharp turn or jump in the throttle quickly, it is the same prop that came with the motor and the spare is the same pitch

 

[GA_Boater]

Try the spare prop next time out.

 

[racerone]

It is very nearly impossible for the clutch dog to disengage with power applied !----Perhaps there is an issue with installation of the motor.----Perhaps motor is too high up.

 

[benningtonr]

Same motor that has been on the boat since 2005 when it was purchased new, just started this last fall with this, boat has been in the family since new.

 

[racerone]

Now that this fact is out in the open try another prop !

 

[benningtonr]

Well i bought a new prop, took her out Friday and all is well. Hallelujah

 

[racerone]

Well, you finally listened to the voices of experience !!

 

[benningtonr]

I did The old prop still looked new and it was checked out at a prop shop. oh well

Thanks Everyone