# How to fresh water flush on Mercury 9.9



## davidpm (Oct 22, 2007)

I did not see any obvious place for the water pickup.
Then I got the bright idea, I hope, that if I picked the engine up after running it and checked quickly I would see where the water ran out which might be the same place as the intake.

So I got to take a couple pictures, not the best standing on my head over the back of the boat.
The first one shows the stream coming from jut below the cavitation plate.
The second one is over exposed but shows the hole just above a bump.

How does one hook a hose up to such a difficult place. I don't see how standard muffs will work?


----------



## Faster (Sep 13, 2005)

I helped with the coach boat for my wife's Dragon Boat team, they had newish Merc 9.9s that had an external circuit that you could disconnect and hook a regular garden hose up to it for flushing. The connector was just beside/outside the cowling, up front opposite the tiller arm.

Worked slick but I don't know if it's standard nowadays or if it was an add-on.

What year is this motor???


----------



## davidpm (Oct 22, 2007)

Don't know the age but it is 2 stroke so have to pretty old I suspect.
Runs great so far.


----------



## 3Kioni (Dec 5, 2008)

The 2 stroke small HP Mercury outboards pick cooling water up through an opening underneath the anti-ventilation plate (sometimes incorrectly called the cavitation plate) just forward of the anode. There is a hose adapter, which has a single "muffler" and spring plate arrangement to hold the muffler over the cooling water inlet. The prop has to be removed to give clearance for the adapter.


----------



## jjablonowski (Aug 13, 2007)

I remember seeing an article in a sailing magazine years ago that described how one owner rigged a floatation collar around a lidded bucket, filled it with fresh water, and tied the floating pool to his saltwater mooring. 

Before leaving the boat, he'd pull the bucket up to his stern, lower the outboard motor into it to run a couple of seconds in fresh water, then hoist the motor.


----------



## davidpm (Oct 22, 2007)

3Kioni said:


> The 2 stroke small HP Mercury outboards pick cooling water up through an opening underneath the anti-ventilation plate (sometimes incorrectly called the cavitation plate) just forward of the anode. There is a hose adapter, which has a single "muffler" and spring plate arrangement to hold the muffler over the cooling water inlet. The prop has to be removed to give clearance for the adapter.


That sounds like what I have.

I'll see if I can find a link to one on-line. If anyone happens to run across it please post it.

It will be a pain to remove the prop while it is in the water.
Maybe the bucket or bag idea will be easier.


----------



## habu (Jul 15, 2013)

I have the new 4 stroke and no it does not have the connector for the hose either, only way to flush is with the clamp on flush things they make. only the larger motors have the hose attachment


----------



## T37Chef (Oct 9, 2006)

Are you certain Habu? I have the 4 stroke 9.8 Tohatsu (sister of the Merc) and you can flush with ear muffs or use a hose and adapter. Mine is a 2010 model


----------



## arvicola-amphibius (Apr 14, 2012)

During the season, when it gets frequent use, I don't bother with fresh water flushing my 2 stroke Merc at all. You don't see professional fishermen bothering to do this, and in third world countries they probably never do it either. Yet these little two strokes go for a very long time.

At the end of the season my outboard gets a special treat in a very large bucket of fresh water, being topped up by hose as necessary. A good 10 minute run at about half throttle (in neutral gear, of course!).

Then I run the carb dry, change the lower leg oil, pull the spark plug, spread a bit of inhibitor spray around inside and outside, replace spark plug and put it to bed. During the winter I pull it over on the starter occasionally. Come next season it fires up first go. Motor is now 5 years old and still looks new.


----------

