1970 Mercury 20 HP Problem

On 8 May 2005 14:35:02 -0700, jburnett RemoveThis @tcon.net wrote:

>I have a 1970 20 HP Mercury. The engine is running fine, but the last
>time we had it out something seemed to break between the engine and the
>prop. The prop will turn when the engine is running slow, but when
>trying to run faster the engine revs and the prop won't turn any
>faster. (Like a clutch is slipping.)
>Any suggestions? .............. Thanks, John...

You spun the prop hub, thus you need a new prop.

You may be able to get the old prop rehubbed depending on condition.

Later,

Tom
 >> Stay informed about: 1970 Mercury 20 HP Problem 

Spun prop hub.......... take it to a prop shop or get a new prop.

-W

<jburnett.RemoveThis@tcon.net> wrote in message
news:1115588102.634458.292330@g14g2000cwa.googlegroups.com...
> I have a 1970 20 HP Mercury. The engine is running fine, but the last
> time we had it out something seemed to break between the engine and the
> prop. The prop will turn when the engine is running slow, but when
> trying to run faster the engine revs and the prop won't turn any
> faster. (Like a clutch is slipping.)
> Any suggestions? .............. Thanks, John...
>
 >> Stay informed about: 1970 Mercury 20 HP Problem 

Clams Canino wrote:
> Spun prop hub.......... take it to a prop shop or get a new prop.
>
> -W
>
> <jburnett DeleteThis @tcon.net> wrote in message
> news:1115588102.634458.292330@g14g2000cwa.googlegroups.com...
> > I have a 1970 20 HP Mercury. The engine is running fine, but the
last
> > time we had it out something seemed to break between the engine and
the
> > prop. The prop will turn when the engine is running slow, but when
> > trying to run faster the engine revs and the prop won't turn any
> > faster. (Like a clutch is slipping.)
> > Any suggestions? .............. Thanks, John...
> >

Thanks for the inputs, but, what is a "spun prop hub"? I pulled the
prop and the hub splines look ok...
 >> Stay informed about: 1970 Mercury 20 HP Problem 

The entire prop has three layers - the inner metal hub that is in
direct contact with the engine's prop shaft, the outer prop itself, and
a middle layer which is made of hard rubber, is bound tightly between
the two layers, and is designed to break free if the prop impacts a
solid object - to protect the inner gears and such.

"spun prop" means there is slippage between the rubber hub and the
other part(s). Bottom line is, in the water, the engine will turn the
prop shaft, but the prop itself slips due to the load of the water.
That's why it will be more obvious at higher rpms in the water as
opposed to idling or on the hose.

Specialized prop shops have equipment to install new rubber hubs. This
is worthwhile on larger expensive props. Your 20's prop is probably in
the vicinity of $75 or so, so it may or may not be worth while -
especially depending on the overall condition of the prop. If it's
dinged up, it's probably smart and cost effective just to buy a new
prop.
 >> Stay informed about: 1970 Mercury 20 HP Problem 

On 9 May 2005 14:53:27 -0700, "jburnett@tcon.net" <jburnett RemoveThis @tcon.net>
wrote:

>
>Clams Canino wrote:
>> Spun prop hub.......... take it to a prop shop or get a new prop.
>>
>> -W
>>
>> <jburnett RemoveThis @tcon.net> wrote in message
>> news:1115588102.634458.292330@g14g2000cwa.googlegroups.com...
>> > I have a 1970 20 HP Mercury. The engine is running fine, but the
>last
>> > time we had it out something seemed to break between the engine and
>the
>> > prop. The prop will turn when the engine is running slow, but when
>> > trying to run faster the engine revs and the prop won't turn any
>> > faster. (Like a clutch is slipping.)
>> > Any suggestions? .............. Thanks, John...
>> >
>
>Thanks for the inputs, but, what is a "spun prop hub"? I pulled the
>prop and the hub splines look ok...

Think of a double threaded insert - that is essentially what a hub is.
The hub is spinning properly on the driveshaft - what is happening is
that it is spinning inside the prop hub. The connection to the
driveshaft is fine, the connection to the prop isn't.

Later,

Tom
 >> Stay informed about: 1970 Mercury 20 HP Problem 

Rubber bushing in the prop spins freely............. should not.

-W

<jburnett DeleteThis @tcon.net> wrote in message
news:1115675607.677691.125930@o13g2000cwo.googlegroups.com...
>
> Clams Canino wrote:
> > Spun prop hub.......... take it to a prop shop or get a new prop.
> >
> > -W
> >
> > <jburnett DeleteThis @tcon.net> wrote in message
> > news:1115588102.634458.292330@g14g2000cwa.googlegroups.com...
> > > I have a 1970 20 HP Mercury. The engine is running fine, but the
> last
> > > time we had it out something seemed to break between the engine and
> the
> > > prop. The prop will turn when the engine is running slow, but when
> > > trying to run faster the engine revs and the prop won't turn any
> > > faster. (Like a clutch is slipping.)
> > > Any suggestions? .............. Thanks, John...
> > >
>
> Thanks for the inputs, but, what is a "spun prop hub"? I pulled the
> prop and the hub splines look ok...
>
 >> Stay informed about: 1970 Mercury 20 HP Problem 

Good explanation...In 50 years of owning outboard motors, I have never
had this happen to me. A local Mercury dealer quoted a price of $102.50
for a new prop and a prop shop here said they would re-hub mine for
about $40. The prop is in good shape otherwise..................Thanks
for the help everybody...........
 >> Stay informed about: 1970 Mercury 20 HP Problem 

On 8 May 2005 14:35:02 -0700, jburnett.RemoveThis@tcon.net wrote:

>I have a 1970 20 HP Mercury. The engine is running fine, but the last
>time we had it out something seemed to break between the engine and the
>prop. The prop will turn when the engine is running slow, but when
>trying to run faster the engine revs and the prop won't turn any
>faster. (Like a clutch is slipping.)
>Any suggestions? .............. Thanks, John...

Sell it, and use the money to pave your driveway.
 >> Stay informed about: 1970 Mercury 20 HP Problem