Muff flush vs. Hose flush

[fairdeal]

Pretty neat, Boscoe!!

would you elaborate on the story behind that "specially modified" F150?

[boscoe99]

Pretty neat, Boscoe!!

would you elaborate on the story behind that "specially modified" F150?

There was debate about water flow back to the water pump when using the garden hose flush fitting. Had a surplus 5 inch spacer available so a sawzall was used to make a cutout in it. Reinstalled the lower unit. Half inch copper pipe fit the water pump outlet tube just nicely so to that we got some vinyl tubing in a size that would slip over the copper pipe. That same vinyl tube fit just nicely over the water pump tube up in the mid-section.

Added water to see the flow. There is plenty of water as can be seen in the photograph. Ran the motor for quite a while. No over temp. No damage to the impeller. Key is to feed the motor sufficient water.

As a side note I had a temperature gauge connected to a sender in the oil sump on this very same motor. Drain plug was drilled and tapped for the temperature sender. At idle the oil temperature was so low it never brought the needle up on the scale. Confirmed my suspicion that this model runs cold. Very cold. Maybe not at power but at idle it was ridiculous. So if someone *****s all the time and complains about their motor it won't surprise me.

One day we can discuss this model being run with a fuel/air meter on it. It runs rich. Very rich. People talk about stochiometric as if that is the goal. The motor comes no where near stoichiometric. https://www.google.com/webhp?sourcei...iometric+ratio

[fairdeal]

Nicely done & very interesting

Not surprising about the cold oil sump - that's the first place the water hits when it leaves the pump, yes?

I can imagine there are a lot of "compromises" made by the outboard engineers, in order to keep it a compact and still very simple package.

I'm not surprised by the "very rich" condition - only because I've been doing some reading on the Etec G2. A remarkable engine....if I live to re-power, that looks to be the sensible choice.

[boscoe99]

Nicely done & very interesting

Not surprising about the cold oil sump - that's the first place the water hits when it leaves the pump, yes?

I can imagine there are a lot of "compromises" made by the outboard engineers, in order to keep it a compact and still very simple package.

I'm not surprised by the "very rich" condition - only because I've been doing some reading on the Etec G2. A remarkable engine....if I live to re-power, that looks to be the sensible choice.

What I am waiting for is a direct injected four stroke model from Evinrude. More and more of BRP's products other than outboard motors are four strokes. Many direct injected.

No more two strokes for me.

[rodbolt17]

the F225 has the same block cooling problem at low speed.
had one last year the guy lives about 1/4 mile from the bridge.
he runs to the bridge and *****s for 4-5 hours then runs home.
out of about 325 hrs the engine had less than two hours above 4000 and over 300 below 1000.

and he wondered why it was making oil.

[throrope]

I suspect Yamaha advises against running the motor on the flush fitting for safety and because it does the job without running. Notice for the bag and muffs Yamaha procedure requires running the motor and includes removing the prop.

[bajakeith]

Tell ya a Lil tip about marine motors

I/O'S, inboards,, outboards are designed to pretty much be in the "run" postion and and good w/p impeller is not gonna like having water trying to close off the vanes with water pressure coming from a not normal direction.no, its not gonna hurt anything...impellers are So not understanded,,at low speeds the impeller spins offset to a Round chamber The "cup" ,,So think of it as a "sucker"and at high speeds must be supple enough to flex out the way and act as centracle pump and is not really pump like you would think...the next time your up on plane,, put your paw over the gunnel into the water & you will find out (fast) what is pushing the water thru your motor at the higher R's....Its not the duty time on a impeller so much,, but,,sitting,sand intrusion and lack of use causes the most issues..and why due we call it a blower, when its really sucking up the fume/air

[boscoe99]

I suspect Yamaha advises against running the motor on the flush fitting for safety and because it does the job without running. Notice for the bag and muffs Yamaha procedure requires running the motor and includes removing the prop.

That is the part that has been part of the debate. How effective is it in doing the job?

For water to flow effectively through the block the thermostat needs to be open. If the motor is not running and warmed up, and is flushed using just the garden hose flush fitting, then the thermostat is going to be closed. Water flow will not be as effective as it otherwise might be.

Yes, there is a small bleed hole in the thermostat across which water can flow but it is miniscule.

Yamaha, like most companies now days, are scared to death of frivolous law suits. Thus the statement to remove the propeller. Which is why the owner's manual is full of crap about safely operating the boat which really has little to nothing to do with use of the motor. Which is why you will never see an official Yamaha boating photo with the folks on the boat not wearing a life vest.

[boscoe99]

I/O'S, inboards,, outboards are designed to pretty much be in the "run" postion and and good w/p impeller is not gonna like having water trying to close off the vanes with water pressure coming from a not normal direction. How much pressure does the weight of water in a three foot high column create? We are talking about a motor at rest, that is being idled, with water being fed to the block via the garden hose fitting. no, its not gonna hurt anything...impellers are So not understanded,,at low speeds the impeller spins offset to a Round chamber The "cup" ,,So think of it as a "sucker"and at high speeds must be supple enough to flex out the way and act as centracle pump and is not really pump like you would think...the next time your up on plane,, put your paw over the gunnel into the water & you will find out (fast) what is pushing the water thru your motor at the higher R's....Its not the duty time on a impeller so much,, but,,sitting,sand intrusion and lack of use causes the most issues..and why due we call it a blower, when its really sucking up the fume/air

There really is no such thing as sucking or suction. There is pressure and a lack of pressure. Pressure lower than some specific value is generally referred to suction. Or a vacuum.

A blower (if we are talking about an air pump aka supercharger) creates a low pressure at its inlet. Ambient air pressure pushes air into the device. The device then increases the air pressure within itself and then pushes the air onward into a lower pressure area which in the case of a piston engine is the intake manifold. Now if the piston is going downward it creates another low pressure area. The intake manifold air pressure, being higher than the cylinder pressure, will push the air into the cylinder.

Air flow is always from high pressure to low pressure. It is the high pressure that is pushing the air. The low pressure is not pulling the air.

[bajakeith]

Ahhh,, OK !! Merry xmas

My God,, I'm gonna get a day off !! Yee Ha !! out of the bilge.............

[captn tj]

There really is no such thing as sucking or suction. There is pressure and a lack of pressure. Pressure lower than some specific value is generally referred to suction. Or a vacuum.

A blower (if we are talking about an air pump aka supercharger) creates a low pressure at its inlet. Ambient air pressure pushes air into the device. The device then increases the air pressure within itself and then pushes the air onward into a lower pressure area which in the case of a piston engine is the intake manifold. Now if the piston is going downward it creates another low pressure area. The intake manifold air pressure, being higher than the cylinder pressure, will push the air into the cylinder.

Air flow is always from high pressure to low pressure. It is the high pressure that is pushing the air. The low pressure is not pulling the air.

Great info: This all boils down to a simple question can I run the engine F225 with muffs (2 sided) on and the prop on?

[boscoe99]

Great info: This all boils down to a simple question can I run the engine F225 with muffs (2 sided) on and the prop on?

Yes. Absolutely, positively.

Make sure there is plenty of water pressure available to the muffs.

Now some Yams don't seem to get enough water to keep the motor cooled using just the muffs. My F200 being an example.

If yours is like mine then get a Y fitting from Home Depot. Also, a short length of garden hose that is about 4 feet long. Connect the muffs to one output leg of the Y. Connect the short hose to the other output leg of the Y.

Connect the outlet of the short length of hose to the garden hose fitting. Connect the normal hose to the input leg of the Y fitting. Put the muffs on the motor. Turn on the spigot as far as she will go. Water will be introduced into the motor in two places. You should soon see water coming from the tell tale. Start the motor. I could run my motor all day long at an idle RPM and it would never over heat doing it this way.

Now when the propeller starts turning in neutral come back here and we can explain it all for you. And if you get nicked by the propeller being on the lower unit it is your own damn fault.

[zenoahphobic]

Boscoe, good comment re pressure in response to Bajakeith.
I would also have questioned his proposition that it is water pressure from the movement of the boat at speed forcing water up the intake to cool the engine. There are two problems with this.
One, the water would force the vanes tighter against the cup limiting the amount that can pass, which is opposite to suggested that the vanes actually flex out of the way.
Two: the intakes are on either side of an aero foil section. An aerofoil (or hydrofoil) has a high pressure and on the opposite side low pressure, depending on its angle of incdence . I suspect if you only had an intake on one side it would either pump water in or "suck" it out, alternating by slight or great rudder change.
Therefore there are equal vents on either side to cancel out any pressure change when this aerofoil moves through the water, leaving the pump unimpeeded to do its job. Notwithstanding that at a certain revolution the resistance of the water being pushed ahead causes the vanes to flex out of contact with the pump sides. This force is even greater than the increasing centrifugal force from the increased revolutions!

[zenoahphobic]

And the reason a simple stainless steel centrifugal pump, as in cars, is not used (would save a lot of maintenance!), because the water head is to great (not level or lower as in an automobile ), and that it is not a closed circulating system. It can't take advantage of gravity cancelling syphoning affect.
As previous threads, it would solve so many other problems when O/B cooling systems eventually become closed systems!

[zenoahphobic]

There is an argument that "suck" is just lower pressure, and then higher pressure outside but connected pushes.
All very well for compressible and expandable gases.
Not always so with liquids, think of a cylinder piston set up.
Fill with water and seal. Push the piston, it won't compress.
Pull the piston it won't move or "uncompress".
It is not outside pressure holding the piston in!
It is the molecular forces within the water stopping this expansion.
So the apparent vacuum is not really there- nothing to with high pressure going to low pressure!
Try the experiment in space, the force required to pull that piston will still be the same.
Zeno is off his head again, what has this to with The OP question?
Dunno , maybe thinking properly about fluid mechanics helps.