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**boscoe99** · 04-05-2015, 10:15 AM

I agree with the dealer. Motor was not deep enough in the water.

The water pump works by pushing water up to the motor. The pump needs to be completely submerged in water to do its job. At least when the motor is first started.

If the impeller is not wet to begin with it sometimes will not, repeat will not, suck water up to itself. Impeller spins in the impeller cup without water to lubricate itself and quickly wears itself out.

Now sometimes if the impeller is wet to begin with (say some residual water remains in it) it will suck water up and start doing its job. But, I would not count on this to happen.

It so much easier to use a Y fitting on the end of a garden hose in lieu of the flush bag. Install the muffs on one outlet of the Y. To the other outlet of the Y install a four foot piece of garden hose from Home Depot. Connect the end of that hose to the garden hose fitting. Turn the tap on wide open. Start the motor. Motor will be getting water from two places. I have never seen a Yam that will over temp at idle when using this configuration.

See the anti-splash plate that projects forward from the lower unit. The water pump is above that plate.

**theflats** · 04-05-2015, 10:58 AM

Originally posted by boscoe99 View Post

I agree with the dealer. Motor was not deep enough in the water.

The water pump works by pushing water up to the motor. The pump needs to be completely submerged in water to do its job. At least when the motor is first started.

If the impeller is not wet to begin with it sometimes will not, repeat will not, suck water up to itself. Impeller spins in the impeller cup without water to lubricate itself and quickly wears itself out.

Now sometimes if the impeller is wet to begin with (say some residual water remains in it) it will suck water up and start doing its job. But, I would not count on this to happen.

It so much easier to use a Y fitting on the end of a garden hose in lieu of the flush bag. Install the muffs on one outlet of the Y. To the other outlet of the Y install a four foot piece of garden hose from Home Depot. Connect the end of that hose to the garden hose fitting. Turn the tap on wide open. Start the motor. Motor will be getting water from two places. I have never seen a Yam that will over temp at idle when using this configuration.

See the anti-splash plate that projects forward from the lower unit. The water pump is above that plate.

thx boscoe, dealer recommends their 50 gal plastic drum cut to proper length. have viewed your technic and appreciate recommendation

**rodbolt17** · 04-05-2015, 08:20 PM

keep playing with bags and barrels and keep changing melted housings.
simply attach a 3/4" garden hose with at least 40 PSI and flush it.
works day after day.

but its also why bike techs.
auto techs and engineers make up the bulk of my work.

Marine is just a bit different.

its also why I don't work on autos nor bikes anymore

.\

the worst are airline pilots with twin engines.

**bajakeith** · 04-06-2015, 10:59 AM

Aint that the truth !

Originally posted by rodbolt17 View Post

keep playing with bags and barrels and keep changing melted housings.
simply attach a 3/4" garden hose with at least 40 PSI and flush it.
works day after day.

but its also why bike techs.
auto techs and engineers make up the bulk of my work.

Marine is just a bit different.

its also why I don't work on autos nor bikes anymore

.\

the worst are airline pilots with twin engines.

**throrope** · 04-06-2015, 05:45 PM

Your owners manual has good guidance.

**boscoe99** · 04-06-2015, 06:12 PM

Originally posted by throrope View Post

Your owners manual has good guidance.

What does one do when one follows the owner's manual, uses flush muffs, and the over temp buzzer sounds?

A. Ignore the buzzer
B. Consult with the dealer if the warning horn activates
C. Stop flushing altogether and give up
D. Use the garden hose flush fitting after making sure that water comes from the lower unit before starting the motor and only running the motor at idle

By the way, do you remove the propeller before using flush muffs? That is what the owner's manual says to do. Must be good guidance.

**99yam40** · 04-06-2015, 06:34 PM

I am sure that would save some dumb azz from loosing his hand or fingers if they decided to have it running in gear and play with the lower unit while flushing

.
Seems they have to cover way too much of what someone might do

**amahaork** · 04-06-2015, 07:57 PM

What is the costly mistake? Burned impeller?

**99yam40** · 04-06-2015, 08:18 PM

and housing

**rodbolt17** · 04-07-2015, 05:59 AM

about the only motor I took the prop off for flushing/testing was the old jonny/rude with hydroelectric shit.
and then only cause I got whacked once, luckily other than my jeans,no damage.
but its like the wifes new hair dryer a few years back.
the owners manual stated not to use it in the tub or shower.

liability.

**Nautical** · 04-07-2015, 09:11 AM

From the photo,looks to me like the impeller was pumping fine in the fall and temps were about normal in your report. The impeller shown was burnt pretty bad, not seemingly from the picture you show of a functioning flush bag and good pee stream. I think a possibility may be that someone started that engine and ran it without any water going to it while in storage.. Check for culprits ??

**99yam40** · 04-07-2015, 09:42 AM

Strange that you had TELL Tail showing water flow while melting impeller.

Only one I ever melted was when sea weed blocked intake. I did not notice until alarm went off
Once cleared it only had flow at high RPMs heading back in.

There was more damage than yours when I pulled it apart, Just a melted blob of rubber no sign of fins left. But it did pump water at high RPMs

**rodbolt17** · 04-08-2015, 07:16 AM

now you know why its a two stage impeller.
at low speeds it acts as a positive displacement pump.
at higher speeds the blades actually move away from the cup and it becomes a centrifical pump.

either way its NOT self priming and will overheat and melt in about 30 seconds if dry.

**theflats** · 04-08-2015, 07:21 AM

Thanks, for all the posts. Yep I &^%$up, still scratching my head why alarm did not sound with this kind of damage. Certainly concerned if there was a possibility this could happen trimmed in shallow water ?? Like most of us we all have (or at least some of us middle class back yard mechanics) attempted to do most simple procedures as flushing which have been the norm for previous owned engines. The barrel set-up mentioned is what local dealer currently used, with housing submerged. Further comments appreciated

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