boat wants to burn out

[91 boat owner]

i have a 1991 starcraft fish ski, with a 4.3 mercruiser and a alphaone out drive. just put in new motor and have had outdrive off and split several times in past 2 weeks, boat runs and drives great except for the fact it want to run up on rpms once in a while, always under a load(while i am trying to get out of the hole or plane out, or at high Rpms and speed), have been told its the prop(that the rubber is bad), but i cant turn it by hand, when its off out of the water and in gear( any info will help greatly thanks to all that give me info

 

[Howard Sterndrive]

Re: boat wants to burn out

have been told its the prop(that the rubber is bad), but i cant turn it by hand,

try another prop

If you ever can turn a spun prop hub with your hand, you don't need a boat.... just swim with the waterski rope tied to your waist

big fat guys like me can sometimes get them to slip by jumping on the prop blade...sometimes

 

[HT32BSX115]

Re: boat wants to burn out

That's good!

 

[91 boat owner]

Re: boat wants to burn out

not exactly the answer i am looking for, would, like to know if there anything else that can cause my problem and if u can tell conclusively if a prop hub is getting bad

 

[Howard Sterndrive]

Re: boat wants to burn out

not exactly the answer i am looking for

what answer are you looking for?
$50 dollar prop not exotic enough?
It's the answer everyone dreams of.

You want a 12 page dissertation outlining every possible cause of your symptom?

Put the spare prop on and go try it. If that doesn't fix it, we'll give you the next most probable cause.

 

[91 boat owner]

Re: boat wants to burn out

i hope its the prop, but wondering if there is anything else that could be disingaging, and causing it to rev out of site and act like it came out of gear

 

[91 boat owner]

Re: boat wants to burn out

there is a new coupler plate between the motor and the outdrive, so i am hoping it is not that, had to replace because the person that owned boat before me tried to take motor out without pulling motor away from outdrive shaft and bent old coupler plate

 

[91 boat owner]

Re: boat wants to burn out

and other than trying to spin prop, is there any other way to tell if a prop hub is bad?

 

[180shabah]

Re: boat wants to burn out

did you realign the engine after the new coupler was installed?

Poor allignment will burn one up quick.

Get some of your wifes favorite nail polish and mark the prop. Go run the boat under load, when the RPM's shoot up, shut it off and check the marks, if they no longer line up, prop hub is bad. If they do still line up, we need to look elsewhere.

What condition is the prop in? Dings, chips, nicks.....

 

[HT32BSX115]

Re: boat wants to burn out

I had a similar thing happen to my previous boat. (A 1966 Mark Twain, 150 Mercruiser ....{dad bought it new})


I was running around the lake and it appeared to "slip" a couple of times at high speeds.

The next week went back to the lake and when I put it in gear, it made a slight "zzz" sound and acted like it was out of gear (whilst in-gear)

The engine coupler is bolted to the flywheel on the crankshaft. It's basically a rubber "dough-nut" with an aluminum splined hole in the center that the steel drive shaft "yoke" to the drive slides into. If the engine is not properly aligned (or the coupler is 39 years old like mine was) the aluminum splines wear out.

When I pulled the engine it looked like someone had put the coupler on a drill press and drilled out the splines!! They were gone! mis-alignment will cause it directly in relation to how mis-aligned it is. (the more mis-aligned, the faster you destroy the coupler)

For this reason (and a few others), Mercury suggests checking the alignment every 100hr or once a year. (which ever is sooner)

Your discription sounds a LOT like that. It's very common. You need to pull the drive and have a close look at the bellows, U-joints, and splines. You'll need to flashlight and you may not even be able to see all that well into the coupler.

If the coupler has indeed failed, the engine has to come out to replace it.


Cheers,

Rick

 

[HT32BSX115]

Re: boat wants to burn out

there is a new coupler plate between the motor and the outdrive, so i am hoping it is not that, had to replace because the person that owned boat before me tried to take motor out without pulling motor away from outdrive shaft and bent old coupler plate

If that's really the case, the previous person probably didn't align the engine properly or align it at at all....

Some people think it's ok to use a drive yoke to do the alignment. Sometimes it works and sometimes it doesn't.

 

[91 boat owner]

Re: boat wants to burn out

did you realign the engine after the new coupler was installed?

Poor allignment will burn one up quick.

Get some of your wifes favorite nail polish and mark the prop. Go run the boat under load, when the RPM's shoot up, shut it off and check the marks, if they no longer line up, prop hub is bad. If they do still line up, we need to look elsewhere.

What condition is the prop in? Dings, chips, nicks.....

prop is in far condition, and had a boat shop set in and align the motor, but when i puschased boat prop had wrong nut on it and no locking washer for nut, like someone just threw prop on there

 

[91 boat owner]

Re: boat wants to burn out

and what prop do i want, i have a 19.6 ski fish fiberglass boat with a 4.3? (and do all mercruiser props fit all mercruiser outdrives?)

 

[91 boat owner]

Re: boat wants to burn out

saw boat shop u alignment tool on my boat(so i hope they did it right)

 

[HT32BSX115]

Re: boat wants to burn out

If you don't know what the correct prop for your eng/drive/boat is use the Mercury Prop Selector to get in the "ballpark"


http://appcenter.mercurymarine.com/propSelector/home.do


A good starting place might be the prop you have. The model number, pitch etc is usually stamped on the prop.

 

[180shabah]

Re: boat wants to burn out

alphas, and bravos (not the B3) use the same hub on the props so they are interchangable 'ish

You still have to watch overall diameter and rake, don't want the blades whacking the case or the torque tab.

 

[Gary H NC]

Re: boat wants to burn out

Did you ever mark the hub and prop and see if it stayed aligned after a test run?

 

[91 boat owner]

Re: boat wants to burn out

Did you ever mark the hub and prop and see if it stayed aligned after a test run?

no i did not, but will try that today if i quits raining here
thanks for info

 

[91 boat owner]

Re: boat wants to burn out

alphas, and bravos (not the B3) use the same hub on the props so they are interchangable 'ish

You still have to watch overall diameter and rake, don't want the blades whacking the case or the torque tab.

thanks for info , greatly appricitated

 

[180shabah]

Re: boat wants to burn out

Did you ever mark the hub and prop...

Doubt it, it's only been 28 minutes.