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Old 07-29-2013, 04:53 PM   #1
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Default Bravo II Prop Slipping, Bad Hub?

When trying to plane out my Port engine (1998 Maxum 3000SCR, Twin 4.3 / Bravo II) seems to vary the RPM a bit, engine shoots right up to around 4000rpm and then fluctuates a 500-750rpm difference, I first thought it was cavitation but then read a lot about the Hubs going bad. This is my first year with this boat but this problem only started happening recently. I have not hit anything and my props look fine. I do not have a trailer to yank the boat out and its close to the end of the season so would like to try an in-water repair if possible, IE. Changing Prop.

First does anyone know what props should be on this boat? I know they are original as I am the second owner, if I could just buy a new prop to try that would be easiest.

Are the hubs removable? I have a press so I would assume if they are not bonded in that they are just pressed in. I can find bravo 1 prop hubs but nothing on bravo 2.

My buddy has a bunch of extra Stainless Bravo 1 props, is the prop hub/exhaust all same locations and maybe I could just put one of his of a similar size on to try it to rule out the bad hub/limp around until I get the correct prop?

Thoughts?
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Old 07-29-2013, 05:03 PM   #2
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at the dock, with the engine off and the drive in gear, reach down and try to turn the prob by hand, turns-bad, no turns good.

if bad,

stick your head behind the engine with a flash light and look for aluminum and rubber shaving laying all over the steering lines.

if you see this, your engine coupler is sheered, as it is a rubber donut with an aluminum sleeve which attached to the fly wheel.

They last about 10 years, and the engine goto come out to replace.

this is why people sell boats...
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Old 07-29-2013, 08:27 PM   #3
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Per maxumcustomercare.com, your boat has the following original props for that set-up:

P/N 51728 18-1/4 X 19 RH PROP 1.0 EA
P/N 55066 18 1/4 X 19 LH PROP,ALUM 1.0 EA


Good luck finding your problem. The hub sounds like the most likely culprit, but PAS may be right with the engine coupler. Keep us apprised.

-JP
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Old 07-29-2013, 10:24 PM   #4
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Yep either hub or coupler. I spent $150 5 years ago having a new hub installed but that included a complete prop check as well. Blades were in good shape no nicks.
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Old 07-29-2013, 10:35 PM   #5
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Quote:
Originally Posted by pascavone View Post
if you see this, your engine coupler is sheered, as it is a rubber donut with an aluminum sleeve which attached to the fly wheel.
They last about 10 years, and the engine goto come out to replace.
this is why people sell boats...
I might shoot down to the Marina tonight, Boat is pretty underpowered, any more then me and my wife she wont plane easy and if a engine has to come out, it sure will be being upgraded to atleast a basic SBC. Hopefully its not this, IF it is, never seeing one before, how long would they last being easy on the boat before that drive wont turn anymore? I assume it is just a rubber bonded to metal like a Harmonic Balancer, and once they spin they can just come right apart with no sort of safetys/locks or anything to keep em spinning.
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Old 07-29-2013, 10:37 PM   #6
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Quote:
Originally Posted by mmwjr View Post
Yep either hub or coupler. I spent $150 5 years ago having a new hub installed but that included a complete prop check as well. Blades were in good shape no nicks.
Obviously I am hoping for this, I have not smelled anything burning except one day, before this happened, but turned out to be my blower fan melting out of its body.
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Old 07-29-2013, 10:38 PM   #7
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Quote:
Originally Posted by CountryME View Post
Per maxumcustomercare.com, your boat has the following original props for that set-up:

P/N 51728 18-1/4 X 19 RH PROP 1.0 EA
P/N 55066 18 1/4 X 19 LH PROP,ALUM 1.0 EA


Good luck finding your problem. The hub sounds like the most likely culprit, but PAS may be right with the engine coupler. Keep us apprised.

-JP
Awesome! Thanks for the info! Looking through this site now for any other useful info!

Would the LH Prop be on the Port Engine?
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Old 07-29-2013, 10:54 PM   #8
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When the splines on your coupler wear to a point they will then sheer off and their done. If they have sheered off, there would be no way you could get that boat on plane with a single 4.3. The coupler won't slip from splines or rubber failure it will just not turn your drive at all.
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Old 07-30-2013, 04:25 AM   #9
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i've never heard of a 3000 scr with V-6's before.

Spiking RPM is coupler slip.

The rubber donut is to kill vibrations in from the engine, and is a pressed fitting.

If its a aluminum failure, its too many bottom strikes.

If a rubber failure, its a miss align engine to drive, which means the engine motor mounts need to be adjusted.

The good news its the new couple is a $400 disk that just bolts to the flywheel, and if you have an A-frame, you could raise the engine out to replace.

They make a steel couple upgrade, that has more splines so, any problem would result is a broken U-joint in the drive.
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Old 07-30-2013, 06:09 AM   #10
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A miss aligned engine can take out aluminum splines as well. The rubber portion of the coupler is vulcanized not pressed in place. And the upgrade to steel coupler has the exact same number of splines as the aluminum, it is recommended for low rpm work applications or high performance. And lastly you would most likely destroy some gears before a u-joint broke. Also if its a strike and it takes out your drive it's covered under you insurance, but they won't cover a coupler failure.
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