Flushing the Yamaha outboard when returning to the dock

B

baz

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Fluid Motion Model
C-24 C
Subject: Flushing the Yamaha outboard when returning to the dock

It's probably common knowledge I believe that when having an outboard such as the Yamaha motor on the R-23/R-27 that if the boat has been used in salt water the engine needs or should be flushed with fresh water. The Yamaha engines have a special connection for a hose to be connected to perform the fresh water flushing maintenance. Typically, the first thing I do when returning to the dock is to connect the fresh water hose to the engine fresh water flush connector and let fresh water flow while I'm doing other things. The flush takes maybe 5 or 10 minutes at best.

Now to my question.... The engine has an impeller and a pump housing for it. When the engine is stopped the impeller stops rotating. The impeller rotates in a sort of elliptical shaped housing which creates the suction for drawing water into the pump housing and then forces it into the engine's cooling system. With the impeller being stationary when the engine isn't running I assume the fresh water being pushed through the engine cannot pass by all the impeller vanes. This then will mean that some salt water could remain in the impeller housing. Thus the question is .... when flushing the engine with the fresh water should the engine be turned over just a bit to ensure no salt water residues remain in the impeller housing ?

The Yamaha User Manual makes no mention of this aspect and in fact states to flush with the engine stopped.

What are your thoughts about this ?
 
I'm certainly no expert, but I think it wouldn't do any harm to run the motor at idle on the hose. I flush my I/O all the time with it running.
 
If you are using the flush attachment on the midsection cowl, that is a back flush. That flush will flush the block and the water drains down the midsection and drains out the water inlets/outlets on the lower unit. I wouldn't run the engine while doing the flush threw the cowl flush. If you want to insure a full flush of the water pump and water tube attach a flushing devise to the Lower unit water pickup turn water on and now run engine. This is a pain when leaving the boat in the water. I would do this on a scheduled maintenance not every time I use the boat. The difference between the two flushes is when flushing with the cowl flush the engine is cooled and thermostats are closed ( water still passes thru the block thru passage ways by-passing thermostats - Water doesn't flush the pump and pick up area. When flushing with flush devise attached the lower unit ( old way ) the engine is running and can come up to temp, opening the thermostats ( removing deposits ) and flushing the pump housing and impeller. If you flush with the cowl flush each time you use the boat, and rinse the entire outside of the outboard with fresh water after each use it will be around for a long time. At maintenance time flush it the (old way)!
Brian Brown
Cutwater 26
PORT-A-GEE
 
One of the things I've found to be helpful in flushing an outboard I have on one of my boats is Salt-A-Way. I you use it when the engine is running,and it does a great job flushing out the lower unit and ensuring a steady flow of water to keep the engine (a 50 hp Merc) cool.

J
 
johnniethek":5rbe1q6a said:
One of the things I've found to be helpful in flushing an outboard I have on one of my boats is Salt-A-Way. I you use it when the engine is running,and it does a great job flushing out the lower unit and ensuring a steady flow of water to keep the engine (a 50 hp Merc) cool.

J
Click to expand...
As much as I liked Salt-A-Way for cleaning the boat (and I used it once for my R-25) my Marina is a stickler about keeping the marina waters in pristine condition so they can keep their 'Clean Marina Certification'. The one time I used Salt-A-Way I was terrified of all the white suds that started to engulf the water surface around my boat and slip and which eventually starting to drift out into the rest of the marina. Other boaters gave me very nasty looks and later I was told by the Marina's Operations person not to ever use Salt-A-Way again. 😱 😳 :roll:
 
I can understand that...I use it exclusively in my driveway.

But I can see where the overflow of its solution can be problematic if it's used in the water...

Stuff still works really, really good, though. 🙂
 
One way to flush at the dock (and what we do): use a set of muffs that have a good seal around the water intakes. Turn on the water. Lower the engine so that the skeg (and the muffs) are under water. Start the engine. You should have a good flow of fresh water. Let it run for a few minutes, turn off the motor, raise the motor, turn off the water, remove the muffs. Hook the hose to the back flush connection and run some fresh water through that. Then, using the same hose, give the exterior of the motor a good fresh water bath.

Any time the boat is out of the water, it gets an extended fresh water flush.

There are quite a few commercial operators in our area who use outboards and don't mess with flushing them, other than when the boat is out for maintenance.
 
A word of caution on Backflushing based on experience, make sure all of the air is out of the hose first!! And check to make sure that the water is coming from the proper places on the engine.

My first week with my R23 I blew the backflush hose off of the block and ran fresh water down the inside of the cowling. I am guessing that air in the line popped the hose off of the connection point, although I don't believe the zip tie was tight enough as I was able to simply slip it back on. I am forced to use two hoses to get to the hose spigot and might not have run the water long enough prior to hooking up to the black. Not sure what caused the problem but I caught it quickly and now always make sure that I see water coming from the proper places before I walk away and on to other things.

I replaced the zip tie and hope to have Yamaha look at it for me at the Rendezvous, but you can imagine what was going through my head when I saw water pouring from the cowling of my brand new boat.

All ended well, no harm, but it could have been worse had I not been paying attention, and that is certainly a possibility as folks always stop to chat about the boat ;-)

Jim
Next Ten
 
On both my F300 and the 9.9 kicker motors I found the screw cap that engages the hose end sticks badly and when rotated to engaged the hose end will cause its attached rubber tube to twist up badly. I chatted with my local Yamaha shop and they told me this is typical of new motors and to simply apply some grease to inside the screw cap to free it up. It should rotate easily without twisting up its attached rubber tube. They demonstrated this for me using a new motor in their shop. 😉
 
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