BoatBanter.com - View Single Post

John H[_2_]

On Tue, 08 Mar 2011 02:13:09 -0500, wrote:

On Mon, 7 Mar 2011 19:51:27 -0800 (PST), Frogwatch
wrote:

Normally, I don't hesitate to try to fix anything but as I get older,
I realize it is silly to try to do everything. So, now that it is
time to replace the water pump impeller on my 90 hp Yamaha OB, should
I do so or is it simply a PITA that I should get a shop to do? It
involves dropping the lower unit taking apart the pump, aligning stuff
and finally replacing the lower unit. I am not sure how heavy the
lower unit is.
This is mostly a foolosofical question; should I pay to have it done
even though I know I can do it? How wimpy would you feel if you paid
someone else to do it? I know, its really a stupid question as I've
fixed everything from electron microscopes to diesel engines (yup,
fixed so they caint never work agin) so I got nuthin to prove but
paying someone else to work on my boats rarely works well.
I s'pose I am looking for a good reason to wimp out of doing this.

The only real trick is if it doesn't come apart easily and that is not
uncommon with salt water motors.
Be damned sure you get real antisieze compound for all the bolts when
you put it back together so it comes apart next time. The other thing
that can hang up is the shift shaft. That can be ugly too if the
coupler doesn't let go before it pops the Jesus clip and pulls the
shift shaft out of the foot. The shift cam falls off and you will see
how a bearing carrier (gears and stuff) comes out before you are done.
The bolts can also come out in a puff of dust that used to be your
casting.
Did I mention that antiseize?
How are you with Helicoils?

Now that I told you what can go wrong, usually you take out 4 bolts
and a nut (up under that MF plate) wiggle it a little and it drops
out. I usually leave one of the bolts about 3 turns in so it comes
loose but doesn't fall. Then take out the last bolt and slide it out.
There are 2 schools of thought on which gear you want it in. Some say
fwd, some say neutral.
If you don't screw with anything, it should go right back in. I like
fwd because you can turn the prop a little to help the drive shaft
splines mesh.
The whole thing is 30-40 pounds (my guess)
Once you have it on the bench there are some screws that hold the cup
(centered over the drive shaft) take that off and the impeller is
inside. You can either just replace the impeller and reuse everything
else, get the kit with the lower wear plate or the entire kit with a
new can and everything. If this is not a lot of hours but a lot of
time you might just need the impeller.

Did I mention the antiseize? Do those bolts too. Don't lose the key on
the impeller. ;-)

Grease all the splined shafts.

Thanks for all that. Well done.