Slipping propellor

[Thomas1981]

Hello,

I'm new on this forum and I really need your knowledge. I have a Bayliner 2655 from 1997 with a Mercruiser 350 MAG and Alpha One Drive.

The boat was the whole winter in the harbour (in the water).

After testing for the first time this summer the propeller started slipping around 2500 RPM. Boats slows down and RPM goes slowly up.

I replaced the propeller(+ hub en washer, org merc. same diameter and pitch) because this had to be done anyway but the slipping is still the same.
Before testing for the first time this year I changed the oil+filters and placed the thermostat. (The previous owner took it out and the engine was always running on 140F).

My questions are:
Are there components in the drive that can slip, except hub? Is there a hydraulic clutch in the system?
There are algies on the bottom of the boat. Of course this slows down the boat, but can it also cause the slipping of the prop?
In which situation can the exhaust gas causes cavitation?

I hope you can help with this problem.

Bye Thomas

 

[Don S]

Re: Slipping propellor

The coupler can slip like a prop, but with a prop or the coupler, it normally starts slipping before 2500 rpm, and usually only works at idle after the first slip.

Is the drive trimmed down enough? You aren't trimming by what your trim gauge says are you?

 

[Eric 3.7LX Alpha 1]

Re: Slipping propellor

No.... the coupler bolted on the back of the engine could also cause slipping, which would require pulling the engine to replace. When the coupler goes there's a good chance you'll smell burning rubber when it's happening.

 

[Bondo]

Re: Slipping propellor

Hello,

I'm new on this forum and I really need your knowledge. I have a Bayliner 2655 from 1997 with a Mercruiser 350 MAG and Alpha One Drive.

The boat was the whole winter in the harbour (in the water).

After testing for the first time this summer the propeller started slipping around 2500 RPM. Boats slows down and RPM goes slowly up.

I replaced the propeller(+ hub en washer, org merc. same diameter and pitch) because this had to be done anyway but the slipping is still the same.
Before testing for the first time this year I changed the oil+filters and placed the thermostat. (The previous owner took it out and the engine was always running on 140F).

My questions are:
Are there components in the drive that can slip, except hub? Is there a hydraulic clutch in the system?
There are algies on the bottom of the boat. Of course this slows down the boat, but can it also cause the slipping of the prop?
In which situation can the exhaust gas causes cavitation?

I hope you can help with this problem.

Bye Thomas

Ayuh,... Welcome Aboard,... There's no clutch, but there's a rubber coupler on the flywheel the drive attaches by...
It Could be slippin'/ worn out/ junk....

But,.... The marine life on the hull can also mimic a slippin' prop,...

I'd clean the hull 1st, as the drives gotta come off, 'n the motor Out to service the coupler....

 

[Thomas1981]

Re: Slipping propellor

Hello,

After reading your comments the first thing I did was taking the boat out of the water to clean the hull.

Surprises:
A hole in the outside layer of the bottom.

The vin of the sterndrive was brokne off.

The nut of the propeller wasn't tight enough.

And of course there were multiple families of plants and shelves living on the bottom and sterndrive.

After I fix all this problems I'm still not 100% is this will fix the slipping. Is there a way to check to coupler without taking the engine out?

 

[dubs283]

Re: Slipping propellor

Is there a way to check to coupler without taking the engine out?

pull the drive, flashlite shining through gimble bearing will show you coupler splines

sounds like you got some other issues to resolve first, im willing to bet you are going to notice a remarkable performance improvement once you fix the issues you stated

 

[Thomas1981]

Re: Slipping propellor

Thanks for all the help.

I know this is a difficult question to answer. But how much time do you need to take off the drive. I'm an experienced mechanic but I more used to work on modern cars, this is completely different.

And to put the engine in gear and turn the propeller to see if it slips, bad idea? will it work?

 

[Eric 3.7LX Alpha 1]

Re: Slipping propellor

Thanks for all the help.

I know this is a difficult question to answer. But how much time do you need to take off the drive. I'm an experienced mechanic but I more used to work on modern cars, this is completely different.

And to put the engine in gear and turn the propeller to see if it slips, bad idea? will it work?

 

[Thomas1981]

Re: Slipping propellor

Well I took out the drive, very easy to do. Especially when the boat is out of the water

I tried to look at the engine coupler but I can see much wrong. I took a picture, maybe some of you can see more then I do?

 

[Thomas1981]

Re: Slipping propellor

I meant I can not see much wrong.

Another view

 

[Bondo]

Re: Slipping propellor

I meant I can not see much wrong.

Another view
View attachment 196021

Ayuh,.... I can just see the splines in this picture abit,...
The coupler is the splined thingy behind that bearin', which looks pretty good by the way,...
The splines should have nice flat tops, not pointy,...

I'm thinkin' gettin' rid of the sea life is gonna Fix the big issue,...

 

[Thomas1981]

Re: Slipping propellor

Yesterday the boat went back into the water. Performances was amazing, acceleration that I never felt before and a top speed of 60 km/h, 38 MPH

Also the fuel consumption should be much lower now.

Thanks for a the help!!!!!