prop slip or coupler how can you tell on 1991 bayliner with 3.0 alpha1 gen 2 drive?

[firsttimertoboats]

Hi everyone I am brand new to boating and I have a 1991 bayliner classic 19ft cuddy cabin with a mercruiser 3.0 alpha 1 gen 2 drive. I have rebuilt the motor and it runs great, The only problem I am having is when I had it on the water it shifted fine but when I got it up to about 4000 rpms it would stop pushing the boat and wind out to 5000 rpms then if I backed down it would grab and I could keep it going fine between 3500 and 3800 any higher and it would slip any thoughts on what to check I am thinking the prop is going bad?

 

[GA_Boater]

Welcome to iboats.

A spun coupler often has the smell of burning rubber with smoke and sometimes the engine will overheat because the impeller in the water pump isn't driven enough. You didn't mention any of those things.

A spun prop does sound like you described. To find out, draw a line across the prop hub with a marker and take the boat out. After it slips, check that the line is still straight. If it isn't, the hub is spun. A prop shop can rebuild a prop and we have new ones in the iboats store - http://boatpropellers.iboats.com/?cart_id=015895223&session_id=910559126

 

[alldodge]

Does the rpm's come down if you trim down a bit?
Do you smell anything like burnt rubber?

 

[firsttimertoboats]

Did not smell any burn rubber and did not try trimming the out drive had it all the way down but if I kept the rpms at 3800 it would run fine.

 

[firsttimertoboats]

how could I check the coupler?

 

[GA_Boater]

how could I check the coupler?

Check the prop first. It is much easier.

But after saying that - Did you do the rebuild and check alignment after installing the motor?

 

[firsttimertoboats]

yes got the alignment tool and worked it until I could slid it in with 2 fingers and the outdrive went on easy don't have any noises or clunking when I run it in the driveway.

 

[firsttimertoboats]

Thank you I will start at the prop. hope it is that easy...lol