Picture of my prop - what’s going on here?

nicholaseb

Recruit
Joined
Oct 9, 2010
Messages
1
I purchased a boat with a mercury 90hp outboard this year. Took off prop to examine during winterization and saw the plastic piece inside all cracked and such. This picture is showing the back of the prop. What is this, do I need to replace, and Can I replace just the plastic piece? Thank you 4059278F-2E89-4AB3-91E7-FFED2103D33C.jpeg
 

ONERCBOATER!

Seaman
Joined
Oct 25, 2022
Messages
57
Would like to see whole prop in picture just cause I'm curious as to possible damage. That said I have had sleeve/hub fails due to age and I imagine the Mojave sun and summer temps not great for them either.
 

QBhoy

Fleet Admiral
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Mar 10, 2016
Messages
8,342
Likely as a result of a bottom strike…and to be honest, I’ve never seen one of these sacrifice themselves yet, in person…but must admit, it looks a little strange to me. Firstly, the hub kit normally sits closer to flush to the edge of the prop…secondly, it looks like the actual prop edge has been damaged too. That’s a little strange. Wonder if someone has had a go at trying to pry that out, after it being stuck in. Would explain it being creased over and the damage to the edge.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,852
Normally Mercury prop hubs have longer splines set nearly all the way to the base of the prop. That hub looks more like a Johnnyrude one. Johnnyrude splines are shorter in length, so they do not go toward the gearcase as far.

I would tap it out of the prop housing and see if you can find a number on it.
 

Scott06

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Apr 20, 2014
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Normally Mercury prop hubs have longer splines set nearly all the way to the base of the prop. That hub looks more like a Johnnyrude one. Johnnyrude splines are shorter in length, so they do not go toward the gearcase as far.

I would tap it out of the prop housing and see if you can find a number on it.
The newer flo torq hubs have only a short brass splined section that clocks the propshaft to the plastic hub.
 

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airshot

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Jul 22, 2008
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The area around the sleeve appears to be out of round, just me or do others that ?? Mabey just tired old eyes..
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
13,446
The area around the sleeve appears to be out of round, just me or do others that ?? Mabey just tired old eyes..
Likely just a Distortion from the Camera/Lens/Perspective, even Post Processing of the Image.
 

Yegboats

Chief Petty Officer
Joined
Feb 20, 2016
Messages
518
Like others have said these are desinged to break on impact so the prop spins free from the propshaft to decrease the likelihood of a bent prop shaft. If your prop isnt damaged I agree that ot almost looks like someone tried to pry yours out.
You can replace just the delrin prop sleeve. Buy it from iboats.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,905
Wrong thrust washer and incorrect torque will cause this as stated earlier
 

Grub54891

Admiral
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Jun 17, 2012
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6,078
I’ve had many props off at the shop, with that type of sleeve. The only ones I’ve seen broke are ones that hit something. One of my own did that when I was out on Lake Superior, heard a thump and the wheel jumped a bit, checked the prop and it was fine. Must have bumped a deadhead or the like. At home that’s what I found, the sleeve was broke even though I finished my day without issue.
 

walleyehed

Admiral
Joined
Jun 29, 2003
Messages
6,767
Looks to me like 2 things are possible. 1, Not tightened to the 40-50 ft-lb range or 2, it done exactly what it was made to do and gave out, possibly just above idle and although the prop isn't torn up, the hub has shifted. Rubex hub will fix any issues that plastic has.
 
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