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.