I have a 1979 115hp Evinrude outboard. We're
trying to change the impeller. We removed a
bolt which held the top of a shaft in a bracket
in the top part of the motor, then removed 5
bolts from the lower end and tried to drop it down,
but it is stuck somehow. Can anyone offer any
advice on this, and/or know of a place online
where there's a diagram or explanation of how
to change an impeller?

Thank you for any help!
David

wrote:
I have a 1979 115hp Evinrude outboard. We're
trying to change the impeller. We removed a
bolt which held the top of a shaft in a bracket
in the top part of the motor, then removed 5
bolts from the lower end and tried to drop it down,
but it is stuck somehow. Can anyone offer any
advice on this, and/or know of a place online
where there's a diagram or explanation of how
to change an impeller?

Thank you for any help!
David

There's a boat underneath the trim tab. The trim tab looks like a
little vertical wing, and it makes the boat track straight. Mark it's
location prior to removing it.

basskisser wrote:

There's a boat underneath the trim tab. The trim tab looks like a
little vertical wing, and it makes the boat track straight. Mark it's
location prior to removing it.


Well, actually a "bolt" underneath the trim tab ;-) And yes, I make a lot of
typos in my posts as well, so I'm not making fun of your freudian slip.

Back to the other posters question about changing the water pump impeller:

If you haven't done this before its a good idea to buy one of those shop
manuals for your motor. Most boat stores have one.

Also, in addition to the impeller, there are a couple of steel plates and
a gasket or two that you probably need to replace if the impeller has shelled.

To remove the lower unit you'll need to remove _all_ of the bolts including the
one under the trim tab, and disconnect the shift shaft linkage. If its been a
while since the lower unit has been pulled, it still may be stuck by the alignment
pins or drive shaft. Once you are sure that you've removed all of the bolts, use
a dead blow hammer or rubber mallet to gently tap on the lower unit. Be ready
to catch it when it breaks loose. The unit is made of aluminum, so tap _gently_
to avoid damaging it. When it starts to break free, you may be able to insert a
large flat bladed screwdriver between the lower unit and downhousing to pry it free,
but do it carefully, or you'll damage it. The aluminum is pretty soft.

Now that you've got the lower unit off, the water pump is visible at the bottom of
the drive shaft, and you can take out the screws and remove the top cap and impeller.
Best bet is to buy a rebuild kit since it includes the gaskets, and the metal plates,
as well as the impeller. If the steel is scratched up it will eat up your new
impeller pretty quickly. If the drive shaft is corroded you will probably have
to use emery cloth to polish of the corrosion before you'll be able to get the
impeller off.

Not sure if the 1979 model is the same as the ones I used to work on, but if it is
there will be a couple of plastic sleeves whose sole mission in life is to help you
line up the water pipes when you go to reinstall the lower unit. Once you realize
what these are for, and how to use them, re-installing the lower unit is a breeze.
Without them, its dang near impossible. Hint--do not discard these The manual
(you did plan to buy it didn't you?) will tell you to use a special grease on the
splines of the drive shaft, and the alignment pins so that you won't have to use
the mallet next time.

Good luck with it

Don W.

wrote in message
...
I have a 1979 115hp Evinrude outboard. We're
trying to change the impeller. We removed a
bolt which held the top of a shaft in a bracket
in the top part of the motor, then removed 5
bolts from the lower end and tried to drop it down,
but it is stuck somehow. Can anyone offer any
advice on this, and/or know of a place online
where there's a diagram or explanation of how
to change an impeller?

Thank you for any help!
David

Get a service manual for the engine. There is an entire procedure to follow,
including the proper torque specifications for mounting the new or old water
pump. Too much pressure will either break the housing or cause premature
wear and/or failure of the pump. And as Don stated, there are many more
items to consider, including using 2-stroke oil or similar when installing
the impeller in the housing.

Your service manual should also show you the signs of wear in the impeller
and other related fixtures including the housing.

Once you get it all apart,don't you have to be carefull not to rotate
the shift shaft or something? Sam

Don W wrote:
basskisser wrote:

There's a boat underneath the trim tab. The trim tab looks like a
little vertical wing, and it makes the boat track straight. Mark
it's
location prior to removing it.


Well, actually a "bolt" underneath the trim tab ;-)

Yeah, THAT one!!!

Back to the other posters question about changing the a
href="http://www.serverlogic3.com/lm/rtl3.asp?si=11&k=water%20pump"
onmouseover="window.status='water pump'; return true;"
onmouseout="window.status=''; return true;"water pump/a impeller:

If you haven't done this before its a good idea to buy one of those
shop
manuals for your motor. Most boat stores have one.

Also, in addition to the impeller, there are a couple of steel plates
and
a gasket or two that you probably need to replace if the impeller has
shelled.

To remove the lower unit you'll need to remove _all_ of the bolts
including the
one under the trim tab, and disconnect the shift shaft linkage. If
its been a
while since the lower unit has been pulled, it still may be stuck by
the alignment
pins or drive shaft. Once you are sure that you've removed all of
the bolts, use
a a
href="http://www.serverlogic3.com/lm/rtl3.asp?si=11&k=dead%20blow%20hammer"
onmouseover="window.status='dead blow hammer'; return true;"
onmouseout="window.status=''; return true;"dead blow hammer/a or
rubber mallet to gently tap on the lower unit. Be ready
to catch it when it breaks loose. The unit is made of aluminum, so
tap _gently_
to avoid damaging it. When it starts to break free, you may be able
to insert a
large flat bladed screwdriver between the lower unit and downhousing
to pry it free,
but do it carefully, or you'll damage it. The aluminum is pretty
soft.

Now that you've got the lower unit off, the water pump is visible at
the bottom of
the drive shaft, and you can take out the screws and remove the top
cap and impeller.
Best bet is to buy a rebuild kit since it includes the gaskets, and
the a
href="http://www.serverlogic3.com/lm/rtl3.asp?si=11&k=metal%20plates"
onmouseover="window.status='metal plates'; return true;"
onmouseout="window.status=''; return true;"metal plates/a,
as well as the impeller. If the steel is scratched up it will eat up
your new
impeller pretty quickly. If the drive shaft is corroded you will
probably have
to use emery cloth to polish of the corrosion before you'll be able
to get the
impeller off.

Not sure if the 1979 model is the same as the ones I used to work on,
but if it is
there will be a couple of plastic sleeves whose sole mission in life
is to help you
line up the water pipes when you go to reinstall the lower unit.
Once you realize
what these are for, and how to use them, re-installing the lower unit
is a breeze.
Without them, its dang near impossible. Hint--do not discard these
The manual
(you did plan to buy it didn't you?) will tell you to use a special
grease on the
splines of the drive shaft, and the alignment pins so that you won't
have to use
the mallet next time.

Good luck with it

Don W.

It's next to impossible to work on one without the manual. It can be
done, but it's not worth the 15 bucks or so that the manual costs.!!!

wrote:
Once you get it all apart,don't you have to be carefull not to rotate
the shift shaft or something? Sam

Well, not really. You DO need to line up the splines when you put it
back together. It's a fairly easy job with a manual.

One more thing to add here....

do not EVER, EVER use 2 cycle or any other petrolium
based oil on a water pump impeller. This will
destroy the rubber in no time.

The principle to "pre-lub" the impeller is right
on the money though.

When I replace the water pump impellers I use
a water based lubricant. (KY Jelly)
(made by wife go to the store to pick that one
up!!! LOL)

Tom

none wrote:
wrote in message
...
I have a 1979 115hp Evinrude outboard. We're
trying to change the impeller. We removed a
bolt which held the top of a shaft in a bracket
in the top part of the motor, then removed 5
bolts from the lower end and tried to drop it down,
but it is stuck somehow. Can anyone offer any
advice on this, and/or know of a place online
where there's a diagram or explanation of how
to change an impeller?

Thank you for any help!
David

Get a service manual for the engine. There is an entire procedure to
follow,
including the proper torque specifications for mounting the new or
old water
pump. Too much pressure will either break the housing or cause
premature
wear and/or failure of the pump. And as Don stated, there are many
more
items to consider, including using 2-stroke oil or similar when
installing
the impeller in the housing.

Your service manual should also show you the signs of wear in the
impeller
and other related fixtures including the housing.

do not EVER, EVER use 2 cycle or any other petrolium
based oil on a water pump impeller. This will
destroy the rubber in no time.

Are you sure?
I think that impellers for positive displacement pumps are made of high
quality oil-resistant synthetic rubber, not of fragile latex used in
condoms.
In every aircraft, hundreds of rubber parts bathe happily in cold naphta
fuel, hot oil and hydraulic fluid!
If in doubt, use electronic silicone paste, silicone oil or brake cylinder
grease but not KY Jelly, it is a water based Sexual Lubricant and it is
useless in machinery applications, it simply dries after half a hour.
Regards, Tadeusz

The impellors are heavy duty rubber, but do you think
that the put in a special rubber synthetic when its
rated to run in water??? In any case, why take the risk
of damaging it in the first place? Letting the rubber
simply sit in its casing filled with oil until its fired
up isnt the best idea. If its in there long enough it will
soften up and prematurely die.

As for the use of KY. Its NOT suppose to be used as a
long term lubricant. In its sealed casing, the lubricant
will stay there till its fired up and simply disolve when
water gets in there.

By no means are boat parts even come CLOSE to aircraft rated
stuff. Lets face it, having a motor conk out because of a failed
part doesnt come CLOSE to having a aircraft come out of the sky
because of a cheap part. Most likely one of many reasons why
aircraft parts are much more expensive than boat parts.

I really can say anything about other type of non petrolium
lubricants... They could work just fine.

Tom


Tadeusz Jerzy Korsak wrote:
do not EVER, EVER use 2 cycle or any other petrolium
based oil on a water pump impeller. This will
destroy the rubber in no time.

Are you sure?
I think that impellers for positive displacement pumps are made of
high
quality oil-resistant synthetic rubber, not of fragile latex used in
condoms.
In every aircraft, hundreds of rubber parts bathe happily in cold
naphta
fuel, hot oil and hydraulic fluid!
If in doubt, use electronic silicone paste, silicone oil or brake
cylinder
grease but not KY Jelly, it is a water based Sexual Lubricant and it
is
useless in machinery applications, it simply dries after half a hour.
Regards, Tadeusz