I have thought of that. My Dad had the exact same problem with his
Mariah. What causes me to doubt that scenario is the fact that I am
getting water into the engine. I popped one of the plugs off of the
port manifold and ran the engine while in the water, and water shot out
of the plug for five minutes after the engine was shut down. I just
hate to drop my stern drive if that is not the problem; however, I am
running out of other options. Which brings me to my next question.
How hard is it to drop the stern drive and replace the impeller if it
comes down to that?

It's only 8 nuts holding on the sterndrive. About 2 hours to do the
work. Buy an upper water pump body kit, Stern drive mounting set,
synthetic gear lube, mutual seal, bellow adhesive, grease for the
u-joints, and 8 new stainless nylock nuts. If the bellows look tired
replace them. If you are having a problem with the shift you might as
well fix it while the drive is off. If you can borrow an engine
allignment tool, do so. Do yourself a favor and buy a genuine
Mercruiser service manual.
Jim

But is it pumping enough volume???


"Weldo60" wrote in message
ups.com...
I have thought of that. My Dad had the exact same problem with his
Mariah. What causes me to doubt that scenario is the fact that I am
getting water into the engine. I popped one of the plugs off of the
port manifold and ran the engine while in the water, and water shot out
of the plug for five minutes after the engine was shut down. I just
hate to drop my stern drive if that is not the problem; however, I am
running out of other options. Which brings me to my next question.
How hard is it to drop the stern drive and replace the impeller if it
comes down to that?

I have a Mercruiser O.E. service manual. I cannot find any procedures
or specifications for checking coolant flow at any point on the engine.
Is there a test port? If there is, does anyone know the
specifications related to coolant flow? I am going to go ahead and
replace the impeller located in the stern; however, I have a sneaking
suspicion that I will remove the unit and find no damage. My factory
service manual does not provide a test procedure for the engine temp
sensor. Does anyone know what it is. I would assume that it is likely
a resistence test. Before I go to the length of dropping the stern
drive, I want to rule out all other possibilities. I really appreciate
all of the advice. I had an impeller fail on a boat with a 5.7 L Bravo
set-up, and it was not like this. It was obvious no water was being
drawn up at that point. Like I mentioned, when I removed the
circualtion pump and hoses water poured out from all directions.

Water pouring out doesn't mean much. If your exhaust is plugged or
restricted, cooling water can't come into or leave the engine. A
defective water pump could push enough water up to the engine to fill
it but not produce the pressure to pump the necessary volume to cool
the engine. There is no spec. that I know of, but I would guess that
the stern drive pump should pump at least 5 gal. per minuite at idle.
Jim

But is it pumping enough volume???

That was exactly problem with my friends mastercraft. He could idle around
and maybe get up to plane speed...some water was getting thru. When he
tried to tow a tube or wakeboard, it overheated right away. Completely
clogged, and it would have overheated at idle as well.

--Mike

"Lost In Space/Woodchuck" wrote in message
...
But is it pumping enough volume???


"Weldo60" wrote in message
ups.com...
I have thought of that. My Dad had the exact same problem with his
Mariah. What causes me to doubt that scenario is the fact that I am
getting water into the engine. I popped one of the plugs off of the
port manifold and ran the engine while in the water, and water shot out
of the plug for five minutes after the engine was shut down. I just
hate to drop my stern drive if that is not the problem; however, I am
running out of other options. Which brings me to my next question.
How hard is it to drop the stern drive and replace the impeller if it
comes down to that?