How long can a Mercrusier 3.0 idle out of the water before there is
any serious damage. My father-in -law pulled MY boat out of the water
with the engine still running at idle speed (hearing aid off), and it
was about 2 minutes before someone came to the rescue. I didn't hear
about it till later and the boat has not been back in the water since.
I can't fire him, his daughter is way too much fun.
HJJ

The raw water pump does not like to run dry that long. There is no way to
tell if yours was fried, but it would be likely that it sustained some
damage, like the impeller ends getting melted. It can still pump, even if
damaged but in my mind it would be suspect. If it has been a couple of years
since you replaced the impeller, then as routine maintence ( and peace of
mind) you may consider having the impeller replaced before next trip. A raw
pump failure can cost you big.

--
Ron White
Boat building web address is
www.concentric.net/~knotreel

On 20 Oct 2004 10:02:06 EDT, "Ron White"
wrote:

The raw water pump does not like to run dry that long. There is no way to
tell if yours was fried, but it would be likely that it sustained some
damage, like the impeller ends getting melted. It can still pump, even if
damaged but in my mind it would be suspect. If it has been a couple of years
since you replaced the impeller, then as routine maintence ( and peace of
mind) you may consider having the impeller replaced before next trip. A raw
pump failure can cost you big.

I agree with Ron.

I don't think the engine will be hurt much, but just in case it did
get hotter than it should have, change the oil, do a quickie
compression test, change the impeller and give it a try.

I don't think it will be toast.

Take care.

Tom

"The beatings will stop when morale improves."
E. Teach, 1717

wrote
How long can a Mercrusier 3.0 idle out of the water
before there is any serious damage. My father-in -law
pulled MY boat out of the water with the engine still
running at idle speed (hearing aid off), and it was
about 2 minutes before someone came to the rescue.

A few minutes at idle isn't likely to have hurt the engine, but if you have
the usual rubber impeller type raw water pump, it may have damaged the
impeller. I'd replace it as a precaution; it's not a big job unless you find
or break something else in the process.

Thanks, I do believe it would be best to replace the impeller. I did
that once, many years ago on a Mercury outboard and as I remember it
was pretty easy to do, but could someone please give a brief step by
step heads-up on replacing the impeller only on a stern drive lower
unit? Thanks,
HJJ

wrote
could someone please give a brief step by
step heads-up on replacing the impeller
only on a stern drive lower unit?

http://www.mercstuff.com/waterpumpinst.htm
You'll probably want to look your pump body over for damage from the dry
run, but you probably won't find any. If your gaskets and face plate are
still in good shape, you can reuse them. Might be a good idea to tear it
down before you go shopping, so you get all the parts you need in one shot.
When you put the new impeller into the pump body, make sure you rotate it in
the correct direction, as illustrated. I find that the hardest part of the
whole process is maintaining pressure on the propshaft to keep the drive in
gear while I slide the lower back onto the upper, but that's mostly because
I seldom have a helper handy. And for gosh sakes, don't forget to put the
trim tab screw back in.

Just an FYI. I would make it part of your regular maintenance schedule if I
were you. Mine gets changed EVERY spring regardless of condition. Cheap
insurance.

Buck
wrote in message ...
Thanks, I do believe it would be best to replace the impeller. I did
that once, many years ago on a Mercury outboard and as I remember it
was pretty easy to do, but could someone please give a brief step by
step heads-up on replacing the impeller only on a stern drive lower
unit? Thanks,
HJJ

Thanks for the links. I have the kit and enough info to give it a try.
I checked with a boat shop and they want $140 plus parts. That's some
good gasoline money for boating. Just don't know what I'll find as far
as the gear case lube moniter goes. If the case is checked and filled
from the engine compartment, then something has to be disconnected
somewhere. Guess I'll find it when I get inside.
HJJ

The gear lube is connected to the lower section via a small passage from the
upper. If you are just dropping the lower there is nothing to disconnect
besides the bolts. Don't forget the one hiding under the trim tab. And you
must fill by pumping the lube in to the bottom drain until it comes out the
top when you reassemble. If you fill from the top you'll just trap air in
the lower unit.

wrote in message ...
Thanks for the links. I have the kit and enough info to give it a try.
I checked with a boat shop and they want $140 plus parts. That's some
good gasoline money for boating. Just don't know what I'll find as far
as the gear case lube moniter goes. If the case is checked and filled
from the engine compartment, then something has to be disconnected
somewhere. Guess I'll find it when I get inside.
HJJ