BoatBanter.com - Flushing an outboard motor

Gene Kearns wrote:
On Sat, 05 Jan 2008 20:33:58 -0500, Dan penned the following well
considered thoughts to the readers of rec.boats:

Gene Kearns wrote:
On 1/4/2008 9:00:08 PM, Dan wrote:
wrote:
On Fri, 04 Jan 2008 19:51:29 -0500, Dan
wrote:
wrote:
On Fri, 04 Jan 2008 13:40:42 -0500,
wrote:
On Fri, 04 Jan 2008 11:24:30 -0500,
wrote:
To flush my Yamaha, here is what I do:

Attach garden hose to fitting built into the motor and
turn on water.
Do NOT run motor while doing this.

Drink a beer

Turn off water and unscrew hose.

If you don't run the motor long enough to open the
thermostat you are
not really flushing the powerhead, only the water
manifold.
There may be some exchange with the water in the
powerhead but there
will be pockets that remain.
The Yamaha was designed and built with this method
of flushing. It's
not an afterthought, and you do NOT need to run the
motor to properly
flush it. In fact, that would be a bad thing to do!

How could it be bad? It's no different than running it in
the water. I
have the built in connection but I still prefer to run it.
Your water pump may feel differently about that.

I don't get your point. When you idle in the water or a tub
there's
nothing but the impeller (water pump) forcing water though
the motor.
On muffs or with the quick connect there's +/- 50psi of
water forcing
itself through the motor. I have a 4 stroke
"Yamamercury". Yamaha on
top - Merc on the bottom.

It is pretty simple, really.

The water pump that is trying to pump water from the bottom
of the engine (the foot) to the top to the water jacket.

During flushing(using the port provided for this), the water
flow is not in the same direction as one (or the pump) would
expect if the engine were running.

Thus, it is a *really* bad idea to run the engine without
water available to the bottom of the engine to be pumped
*up.*

My Suzukis have this feature and the manual says not to
run while using the flushing port. When I moved my boat
down to a dry storage almost within sight of the ramp, I
became concerned that throwing cold tap water into the
flushing port might shock cool the engine. I called Suzuki
engineering and they said *that* wasn't a problem, but they
made a POINT to make sure that I knew that I could NOT
run the engine while using the manufacturer's flushing port.

Of course, your manufacturer's maintenance manual trumps
anything you read here.... what does it say?

It says it *must* be run while flushing. It's a 115HP Merc with a
Yamaha powerhead. Suzuki must have a hell of a system to allow proper
flushing with the engine off.

Just to check that we are talking apples and apples...... how do you
get the water into the engine? Do you hook the hose up *directly* to
the engine... or do you use mouse-ear type flushers.... like these....
http://tinyurl.com/3yu25q

There's a hose fitting on the back of the motor. No muffs.