Spun propeller hub

[Tim Frank]

Been running outboards for a lot of years but until joining these forums had never heard of a spun hub....let alone spun one myself.

So, driving a 1975 Evinrude 6 HP today in lake water with broken-up ice, sudenly got the over-revving/loss of power that seems to be the classic symptom.

Two questions :
1) Does a motor as small as a 6 hp have a "spinnable" hub? Would be nice if this is the problem as otherwise it must be the gearcase and that will be serious $$$$.

2) If this is indeed the problem, do you get the prop repaired or is it cheaper just to buy a new one?

 

[wilde1j]

Re: Spun propeller hub

Does the prop shaft turn when the motor is running (and in gear, if it has a shift function)? If so, the problem is the prop. A new prop for a small motor like yours is not very expensive. Your prop may have a drive pin, which may have gotten lost or sheared. Start by removing the prop and see what's there.

 

[tx1961whaler]

Re: Spun propeller hub

Been running outboards for a lot of years but until joining these forums had never heard of a spun hub....let alone spun one myself.

So, driving a 1975 Evinrude 6 HP today in lake water with broken-up ice, sudenly got the over-revving/loss of power that seems to be the classic symptom.

Two questions :
1) Does a motor as small as a 6 hp have a "spinnable" hub? Would be nice if this is the problem as otherwise it must be the gearcase and that will be serious $$$$.

2) If this is indeed the problem, do you get the prop repaired or is it cheaper just to buy a new one?

Yes you can spin it, and yes you can get it repaired cheaper than getting a new one.

 

[Tim Frank]

Re: Spun propeller hub

Thanks guys....as usual, bang-on advice. Reapir is going to cost $50- vs $120- for a new prop.
I've had to keep using the motor (gently, ~ 1/3 speed) ferrying building material for a project.
Point to point is only a few hundred feet.

I'll be getting it fixed this week, but have a couple of new q's.

What is the general layout/attachment of the hub? Reason I ask is the problem seems to have almost cured itself. Not sure why.
Could you do something like epoxying the two together as a DIY?
For $50- I probably wouldn't bother even if it might work....bnut it is more of a pain taking it apart and bringing into town and being without it for a week.

 

[wilde1j]

Re: Spun propeller hub

The hub is pressed in ... forget trying to glue it. The reason it's not slipping is low load. Doubtful it's self-cured. Shouldn't be harmful to finish the week going a few hundred feet.

 

[cedarjunki]

Re: Spun propeller hub

The hub is pressed in ... forget trying to glue it. The reason it's not slipping is low load. Doubtful it's self-cured. Shouldn't be harmful to finish the week going a few hundred feet.

just a thought... seeing how its a old 6 horse... my 5 horse has solid prop with a pin........ maybe sheard the pin and piece got lodged causing self cure???

 

[tashasdaddy]

Re: Spun propeller hub

probably and easy fix, as it has a drive pin (shear pin) that goes thru the prop, and prop shaft to drive the propeller. remove cotter pin, and prop, bet 2 or 3 pieces of drive pin fall out. 99% it is not the hub.

Part Number: 0307949 $1.55
Description: DRIVE PIN

 

[jrs_diesel]

Re: Spun propeller hub

I have a 72 Johnson 6HP, and it has the drive pin (not a rubber hub). I have a service manual for a 77 HP which also show them still using a drive pin instead of a hub.

Removing the prop is simple.
1. Put gear shift in neutral and disconnect the spark plug leads from the plugs.
2. Remove the cotter pin on the "nose cone" hub.
3. Unscrew the "nose cone" hub from the shaft.
4. Pull the prop off the shaft.

At this point you should see the pin (if it's intact), or the pieces if it's busted.

If it is broken, check the shaft and inside of the prop for damage and repair as needed. Use marine grease and grease the new pin and prop shaft.

 

[Tim Frank]

Re: Spun propeller hub

But would a broken shear pin work at low revs and "free-wheel"/slip after accelerating? If I do a gradual throttle increase it is pretty much OK.

Not the most interesting problem for you guys, but thanks for the input.
I'll take the advice and not even think of trying a DIY.
I'll take the prop off on the weekend and let you know what I find.

 

[tashasdaddy]

Re: Spun propeller hub

Just pull the prop and see. could be a ear of the drive pin holding.

 

[Willyclay]

Re: Spun propeller hub

When TD speaks, I listen! I have a 1973 Evinrude 6HP with the OMC factory service manual plus parts catalog. It lists mine as "drive pin" also, p/n 307949. My understanding is that drive pins are not designed to shear like the older "shear pins" back when props were made of solid bronze. Every motor design has a "weak link" in the drive assembly to protect the expensive stuff in the gearcase. Looking at the prop for my 6HP, it has a pressed-in bronze hub just like my 100HP. While the factory manual does not specifically state it has a slip-clutch hub, my guess is that it does and the one in question here is spun. My only experience with a spun hub was on a 1959 Johnson 35HP and it acted just like the one in this thread; okay at part throttle but slips under load. That said, it could possibly be the clutch dog in the gearcase.

 

[Tim Frank]

Re: Spun propeller hub

No problem with drive pin....defintely is spinning hub.

This got put on the back burner as I ended up planning three projects on the motor that all were inter-related to do all at once
Gearcase reseal, impeller replacement, and sorting out the prop.

Service manual on hand now courtesy of ebay.
Impeller changed, just waiting for a couple of seals.

Took the prop to the dealer (they send it out) and it cannot be rehubbed. The dealer wants 150- for a new one. It is spec'd as an 8 x 7. By convention which # is dia, which is pitch?

iboats lists a three blade at a nice price....any thoughts on +/- of 3 blade vs 2....and with a 6 hp is it even an issue.

 

[F_R]

Re: Spun propeller hub

I'd go with the iboats QA3178R 8x7 @ $79.99. You probably won't find a great deal of difference with the 3 blade. In theory, it should carry a load better, but it is trial and see.

The first number is diameter, second is pitch.