No Speed Difference higher than 1200 RPMs

rtmacias

Recruit
Joined
Jun 16, 2008
Messages
2
I've got an 84 Bayliner Cierra with a volvo penta. This weekend we took the boat out and it ran good on Saturday but Sunday afternoon on the way back I was unable to get any speeds greater than a slow coast at about 1200 rpms. If I kicked up the rpms, the boat didn't go any faster. This was the same in both forward and reverse.

The outdrive can be raised by hand about an inch or two and I don't remember being able to do that. I'm going to pull it out of the water today but don't know what to look for nor how much play it should have. Could this be the problem or am I headed in the wrong direction?

What happend from Saturday to Sunday? I can say that on Saturday the tilt motor was used to drop the prop when it was in gear (a no-no). However, it ran fine afterwards. Also, on Sunday we anchored it out on the water but the anchor didn't hold enough and it washed close to shore with the prop down. I was able to push it back into the water and we kicked up some sand but nothing major. It was immediately after that I unable to get any true speed. It seems as if it's not fully engaging.

The boat has a new worm gear, rebuilt 350 (about 20 hours), water pump, distributor, carb. I had the worm gear changed because I couldn't get any speed when the RPMS were maxed. Heck, it's basically all new except for the outdrive. Help please. At this point I am about to see if popping a hole in the bottom of the boat can at least make it go fast down since it's been depleting my bank account going forward or reverse.
 

Limited-Time

Vice Admiral
Joined
Mar 30, 2005
Messages
5,820
Re: No Speed Difference higher than 1200 RPMs

So does the engine not pick up RPM when you advance the throttle?? Or dose the engine rev up but the boat speed remain the same.
 

rtmacias

Recruit
Joined
Jun 16, 2008
Messages
2
Re: No Speed Difference higher than 1200 RPMs

The RPM revs up with no speed increase. As a matter of fact, it revs up as if it was not in gear...well beyond the 4000 rpm max when it is in gear. It's almost as if it was in neutral.
 

Limited-Time

Vice Admiral
Joined
Mar 30, 2005
Messages
5,820
Re: No Speed Difference higher than 1200 RPMs

Sounds like a spun prop hub. The easiest way to check is to mark the prop and hub, run the boat, then check the marks. If they no longer "line up" you have a spun hub.
 

davidf5252

Petty Officer 2nd Class
Joined
Apr 19, 2008
Messages
168
Re: No Speed Difference higher than 1200 RPMs

Sounds like a spun prop hub. The easiest way to check is to mark the prop and hub, run the boat, then check the marks. If they no longer "line up" you have a spun hub.
that is more than likely it or the sheer pin snapped and if so they are about $4..if you spun the hub in the prop just buy a used one off ebay for cheap and you can change it in 5 minutes...

good luck!!
 
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