Thru Hub vs Pin Prop

[mewhite]

What's there difference between the two props?
My prop isn't turning, but the motor does and every video I see on prop replacement they don't look like mine.
I went to Mercury props, and I saw the thru hub prop and wonder if that is what I have. It doesn't have the lock washer, etc and I'm trying to find if something in the prop gave way when it was run aground.
Thanks for helping the newbie

 

[Texasmark]

Re: Thru Hub vs Pin Prop

Some engines have a slick prop shaft with a hole at the rear and no threads.....been a very long time, maybe two holes: The prop is placed on the shaft, a pin is inserted through the hole in the rear of the prop and the hole in the shaft, a specially made cap fits over the pin to keep it in place and a cotter pin secures the cap. The prop usually has a rubber hub to cushion shifting shock and soften the shock from hitting something. If the pin shears due to hitting an obstruction, the prop spins freely on the shaft. Another thing that would allow the prop to not be firmly locked to the prop shaft is if the rubber hub slips...worn out. This can be detected by marking the bronze part that the pin goes through out to the outside of the prop...the alum part. If the hub slips, after a test run your marks will no longer be in alignment.

Otherwise you have a splined prop shaft, threaded on the end, no holes, that accepts a splined prop hub. In today's market there are plastic replaceable hubs and the older design rubber cushion hubs...function as the hub mentioned above. The plastic hub should be solid unless you stripped it and that would be obvious.....the rubber hub you mark as you did above and look for misalignment of your marks to check for any slippage. These props use a thrust washer on the prop shaft first, the prop, a locking ring, and a self locking nut for Merc. Others may use a cotter pin to keep the nut on.....having a senior moment....forgot what you call a nut with slots in it like you find on the front axle of automobiles....but that is what can be used with the cotter pin.

The advantage to the splined, rubber slip hub over the pin/splined plastic hub, is that this hub recovers nicely from a strike whereas all the others are subject to unrepairable damage when struck. If you are on the windward side of rip rap and the wind is blowing you into the rocks, this single thing could be a life/boat saver. BTDT

What else do you want to know?

Mark

 

[steelespike]

Re: Thru Hub vs Pin Prop

What year and horse power do you have? is it a black Merc?
Mercury had through hubs long before most of the other brands.
Take the prop off and give it a look over.Some brands had splines and a pin.
if it has a remote setup you may have a bad cable and its stuck in neutral.
on very rare occasions props do have a total hub failure.

 

[catfishcarl99]

Re: Thru Hub vs Pin Prop

does your prop look like this?

this is mine. has a 14 tooth spline that goes over the prop shaft and a lil pin goes in the outer hub to keep it from going back and forth. then the plastic prop nut (cone) screws on over the end of shaft with a cotter pin to keep it from spinning.

a NON thru hub. the exaust exits through the trim tab which on mine is called an exaust snout.

in the prop theres a rubber hub that is presses in by a press. of at least ten ton from what ive read. and they get (spun) if it hits something ect. when you give the motor gas it just revs up.these can be replaced at a prop shop or some boat repair centers. not many do it round here anymore. most send then off. i tried it once having it hubbed. the press cracked the hub. so i had to get a new prop. common on older alum props like mine. its about $50-70 re hub. i actually found a new prop on ebay this spring for $40 shipped. there $140 new for my prop so it was a great deal.

to test this theroy on these make a mark on the prop and one on the hub with a perment marker in a straight line. test it. if they dont line up its spun and you need a re hub or new prop.

 

[Bondo]

Re: Thru Hub vs Pin Prop

What's there difference between the two props?
My prop isn't turning, but the motor does and every video I see on prop replacement they don't look like mine.
I went to Mercury props, and I saw the thru hub prop and wonder if that is what I have. It doesn't have the lock washer, etc and I'm trying to find if something in the prop gave way when it was run aground.
Thanks for helping the newbie

Ayuh,... Welcome Aboard,.... It'd be nice if We knew just what yer workin' on....

Merc.s don't use a pin-drive prop, but old OMCs did, I believe...

 

[Robbabob]

Re: Thru Hub vs Pin Prop

~Prop doesn't turn after being run aground~ Seems like the problem is found somewhere in there. Does anything turn in the outdrive when in gear or does the engine labor or stall?

Without pictures or more information, it is a bit difficult to help much further.

Good Luck!

 

[mewhite]

Re: Thru Hub vs Pin Prop

I'm sorry for the lack of info. I think it is an 89 Mercury 25hp 2 stroke Sea Pro. Tiller steering. S/N 0A862720 Model # 1-005211JK
I was going thru some threads last night and saw that there is a pin in the shaft that turns the prop. Could this be the problem?
I put the motor in gear, both forward and reverse and the prop shaft turns freely.
I don't know why I was so hung up on the prop, other than thinking there was some type of pin there that may have broken.

 

[steelespike]

Re: Thru Hub vs Pin Prop

That is splined prop shaft if there is a pin it would be only to position the prop.
Take the prop off and look it over. Most props have a hub in the prop that cushions impact.
On very rate occasions the hub will completely fail.

 

[mewhite]

Re: Thru Hub vs Pin Prop

I can move the prop spline when the motor is in gear (not running).
Is there some type of a shear pin in the prop spline that breaks under stress in the lower unit?

 

[carholme]

Re: Thru Hub vs Pin Prop

The model number is correct (1005211JK) for the s/n (0A862720) however those numbers come up as a:

1005211JK MERCURY 1990 5

Note the 5hp versus 25hp as you are saying

Parts Listing:

http://www.crowleymarine.com/mercury-outboard/547.cfm

You will see under Gear Housing that the prop is splined to the prop shaft and held on with a nut and cotter pin.

So, if you feel that you have a 25hp, something is wrong with the numbers.

Gerry

 

[mewhite]

Re: Thru Hub vs Pin Prop

I copied the numbers and was told the motor size, so I am assuming that it must be a 20 hp.
I didn't remove a cotter pins, but it may have not be replaced at one time. I'll take a closer look at the prop nut.
I don't think that the problem is in the prop, other than it is chewed up a bit now.
How can I check to see if the driveshaft is turning, or what the problem between it and the prop spline?
If I removed the lower unit, would it be OK to start the motor and put it in gear, or is there an easier method to troubleshoot this?

 

[carholme]

Re: Thru Hub vs Pin Prop

Look on the powerhead for a silver dollar sized disc like this to verify the s/n.

http://img84.imageshack.us/img84/8224/391496208.jpg

How many cylinders does it have (sparkplugs)

Gerry

 

[mewhite]

Re: Thru Hub vs Pin Prop

It has 2 cylinders.

 

[mewhite]

Re: Thru Hub vs Pin Prop

I went back to try to find the CORRECT serial number. It is a 1989 Mercury 25hp Sea Pro 2 stroke.
After rereading some replies I looked at the motor again and realized that the shifting link was not attached at the socket.
Probably when my son was docking the boat, he shifted it hard and it popped off.

Should I be concerned that happening regularly and replace the socket, or just not left my son take my boat out, haha.
She's not much, but she's all I have.

Thanks to EVERYONE for helping me with this! This newbie really appreciates the knowledge and am ready for some salt air therapy!

 

[Sea Rider]

Re: Thru Hub vs Pin Prop

You cannot repair properly a prop hub on engines that exhausts through prop as the hub undergoes a press & heat process called vulcanization, which sticks and molds center splines tube to prop wall. To repair is trowing money down the drain, replace for a new prop.

Happy Boating

 

[mewhite]

Re: Thru Hub vs Pin Prop

I was finally got my pictures added. The first is the front of the prop, the second is the rear and the third is the prop spline.

 

[Chris1956]

Re: Thru Hub vs Pin Prop

Ok, looks like a beat up standard Merc prop. Is there a thrust washer on the splined propshaft? If not, their probably should be. Look for some numbers on the prop, as I think you should replace it, and keep it as a spare. Have it checked out for a damaged hub at a prop shop.

 

[Texasmark]

Re: Thru Hub vs Pin Prop

Ok, looks like a beat up standard Merc prop. Is there a thrust washer on the splined propshaft? If not, their probably should be. Look for some numbers on the prop, as I think you should replace it, and keep it as a spare. Have it checked out for a damaged hub at a prop shop.

Don't know what you are referring to with the thrust washer comment. We can see his thrust washer in place on the front of the shaft. What is missing is the prop nut locking washer that fits between the nut and the prop. If you are calling that a thrust washer I guess we have a terminology difference.

"me", as I see it from your pictures, you have no way to lock your prop on the shaft. Merc's common convention, for many 10's of years is a SS stamped plate with the hexagon impression of the hex of the nut....as the nut snugs up down inside the plate and 6 radial squared off "fingers", 3 of which (at one time) are bent down into the back of the prop where an alum ring is with slots to accept the tabs....you put the washer on the shaft, immediately after the prop with the hex detent toward the prop and tabs straight out. You run the nut down and as you are, you position the plate so that the hex of the nut goes into the detent and then together the nut and plate turn together till you get your nut tight.....55 ft-lbs. Then you turn the nut however much needed to get the first set if 3ea 120 degree tabs to line up with 3 slots in the back of the prop. Taking a hammer and screwdriver, bend the 3 tabs down and into the slots thus locking the nut to the prop as insurance against prop loss.

I don't know what you have there for a nut, but the regular prop nut has a hex body, no round (fabricated washer) front to it and a nylon self locking insert at the rear. The nut I see in the picture cannot run into the plate I mentioned above as the round front of it will prevent it. Additionally I see no self locking insert.

My 2c,

Mark