Boat not getting any speed

[jlucas209]

Hello everyone, I'm new to these forums and big boating. I previously owned a 17ft bayliner capri which I have sold, now I am owner of a 1978 27ft bayliner victoria sunbridge. It has a volvo penta chevy 350 5.7L. I recently did a good tune up on the engine (cap, rotor, plugs, points & condenser, plugs, and wires) The engine sounds and runs great but delivering the power is the issue I'm having. The issue very similar to transmission slipping in a car, everything is fine til about 3500 rpm then as I continue to increase the throttle, my rpm's increase but speed does not (feels like a tranny slipping) you can physically hear the engine increase power and etc but it's just like that power isn't being delivered fully to the prop. I purchased the boat when it wasnt running so I cannot say how it was running before. I'm going to be pulling it out the water soon, can anyone give me some ideas on what to check or look for? Thanks in advance!

 

[Scott Danforth]

spun hub on the prop would be my first thought

 

[jlucas209]

spun hub on the prop would be my first thought

How can I test this? Should I try spinning the prop with my hands while in gear or something?

 

[alldodge]

How can I test this? Should I try spinning the prop with my hands while in gear or something?

No Volvo dude here. You could try that to see if you can, but if that doesn't work pull the prop off and have a look inside of the rubber hub, if it's spun you can see it. The prop hub can be spun and you can still not spin it on the shaft unless it's really gone. Since you can get 3500 rpm it probably isn't that bad if it is the hub.

When you rev the motor up on the water are you smelling any burnt rubber smell? If you are then it's a spun engine coupler

 

[Bondo]

How can I test this? Should I try spinning the prop with my hands while in gear or something?

Ayuh,.... Welcome Aboard,..... SoP for that test, is to slap on Yer spare prop, 'n Try it,...

Yer motor builds Waayyy more power than you can exert with Yer hands,...
at 3500 rpms, it's probably over 300 foot pounds,...

What drive is behind yer motor,..?? is it a Trimmable Volvo,..?? Are ya trimmin' the hull up outa the water,..??

 

[jlucas209]

I don't currently have any spare prop, but that is going to be my next purchase. The drive is not trimmable to my knowledge,but my boat does have two trim tabs that I have been trying to mess with as well. I was assuming I wasn't getting a good angle. One other issue is every time I'm in reverse the darn outdrive lifts up and comes out the water. Can that be a sign of another problem?

 

[Barramundi NQ]

Really sounds like a spun hub. When I did mine it stank when I got to the ramp. Would only let me idle, any more than idle it revved its head off.

 

[jerryjerry05]

No rubber engine coupler in something this old.
IF??? it had a bad coupler it wouldn't respond at all.
It has a damper or clutch like thingy.
To test the prop: remove it and on the forward side use marker or scribe a couple of lines across the hub.
Reinstall and go for a ride. Try to make it do it again. After it slips pull the prop and see if the lines have moved.
The kicking up in reverse: the lockdown mechanism is stuck or the locks have the edges rounded.
Or the actuator or the rod isn't free. .

The 2 trim tabs are for initial acceleration.
They should be all the way down as you accelerate they are brought up once your on plane.
Then they are used to level out the boat while riding.

You check the oil in the drive?
What weight oil?

 

[redneck joe]

my friend had a volvo penta outdrive about that age and there is a bolt or two that broke on his, having it lift up in reverse. Cant help on the speed/rpm issue.

 

[jlucas209]

Thanks for the suggestions everyone, I'm going to try marking it then taking it for a drive to see if its moved at all. I'm just having issues getting it out the water, I have it in a marina and don't currently have a trailer :/ there's a couple of lifts for rent but shes too big for them! As for the lockdown mechanism, is there is pic of what exactly that looks like or where it is? Thanks everyone!

 

[jerryjerry05]

No Title

If you can see the section with the #s 40 and up?
That's the tilt lock and release mechanism.
#43 might be stuck in the upper arm.
Or # 50 the edges have rounded off or it might be as simple as a spring broken or missing.
http://www.volvopentastore.com/Inte...on_id.498308761--store_id.366--view_id.786787