We have a super short, yet informative, YouTube video on how and why to flush your Yamaha Outboard Motor. On occasion, we get some nice feedback and questions from that video. We like feedback!
Recently I had a question that was just too technical for me so I contacted the folks at Yamaha Marine for some help and they provided me with a really great white paper that I thought you might like to see. For simplicity sake, I outlined the exact dialogue below. Check it out and let me know what you think.
Question from John
“Without the motor running, the thermostats remain closed. So does this fresh water get to the powerhead region or does it stay in the lower unit area? Is there a yamaha diagram on this mechanism?
Yamaha’s Answer:
The Boater’s Log – Volume 1, No. 5 – Freshwater Flushing Adds Years to the Life of an Outboard
Adding years of life to an outboard is easy and doesn’t cost a dime. What’s the secret? Flush the outboard with fresh water frequently, preferably after every use. It’s that simple.
There are a couple of ways to cleanse the outboard: Use the built-in freshwater flushing device fitting located on the lower cowling on most Yamaha outboards (doesn’t require running the outboard), or use a flushing attachment (flush muffs) to supply clean cooling water through the water inlets on the sides of the gearcase while the outboard is running.
Freshwater Flushing Device
After boating and with the boat on the trailer, trim your Yamaha outboard all the way down, take the keys out of the ignition, and remove the safety lanyard. If the boat is moored or on a lift, the procedure is similar, but trim the outboard up until the gearcase is out of the water to allow fresh water from the garden hose to flow down through the water inlets on the gearcase. Unscrew the garden hose connector from the fitting on the lower cowling, hook up a hose to the connector, open the spigot and let the clean, fresh water wash the contaminants out of the outboard’s water passages for 10-15 minutes. Then turn off the water, disconnect the hose from the connector, screw the garden hose connector back on the fitting, roll up the hose — and the job is finished.
If the boat is moored boat or on a lift, the procedure is similar – simply trim the outboard up until the gearcase is out of the water and institute the above procedure.
Cleaning the outboard by using the flushing device is equally effective if the outboard is hot or cold; the thermostats have bypass holes in them to allow water to circulate through the powerhead and the cooling system.
Do not start the outboard out of the water. Fatal damage to the powerhead, water pump, and other internal components can occur; the water flow from the garden hose via the freshwater flush fitting won’t properly cool a running outboard.
Flushing Attachment (Flush Muffs)
With the boat on the trailer, trim the outboard down until it’s vertical. Make absolutely sure the propeller is clear to move, or remove it. Connect a garden hose to the flushing attachment, and then slide the flushing attachment’s rubber cups over the water inlets on each side of the gearcase.
Turn the water on slightly until you can see water leaking out around the rubber cups. Get in the boat, place the shifter in neutral, start the outboard, and watch for water flowing out of the pilot hole on the back of the cowling. Keep an eye on the flushing attachment to make sure the cups don’t slip off of the water pickups, and don’t rev up the motor while you’re flushing it, as there isn’t enough water pressure to cool the outboard. Just let the outboard run at idle for 10-15 minutes, shut off the outboard, stow the hose and flush muffs, and you’re done.
(Larger outboards may have multiple water intakes – in the bullet on the front of the gearcase as well as intakes on the sides. Flush muffs won’t work on these outboards; you must use the integral freshwater flushing device, instead.)
A Clean Outboard is a Happy Outboard
It doesn’t matter if you boat in saltwater or on inland waterways, flushing an outboard regularly will reduce the buildup of mud, silt, salt, slime, invasive microorganisms, and other undesirable stuff inside the entire outboard, greatly diminishing the potential for cooling system-related problems down the road.
Article by LucyLu
I was born a commercial fisherman's daughter in Cortez, an old fishing village off the west coast of Florida where you can still experience "Old Florida" and get a really good grouper sandwich. I went to school and became an anesthetist, after privileged years of practice, I jumped ship to work in the family business - Cannons Marina. I love my job and the view. I am crazy about my dog. Being out on the water is magical. I still get giddy every time I see a dolphin. Often I brag that I had the opportunity to swim alongside a humpback whale - it was freaky and pretty amazing. Fishing for tarpon and marlin make me happy. My life is no doubt boating, but I also love paddle-boarding cooking and travel. Find me at Google+.
{ 4 comments… read them below or add one }
I have a ‘new’ 6hp 4 stroke Yamaha as well as an older 60hp 4 stroke Yamaha. The 60hp has the hose connector under the edge of the engine cowling and I understand the mechanism of flushing the larger engine. The smaller 6hp has a port into which I can screw a hose connector and flush with a running garden hose BUT is this still to be without the engine running (same as on the larger engine)? The manual is unclear and my vendor seems uncertain. You seem to be assertive which suggests you know what you’re talking about – or maybe you’re simply assertive
Advice is welcome. Thx.
Hi LJB,
Very good question! As a matter of fact you can do both. Neither option will harm the outboard engine. The lower flush is made to flush the engine while it is running and water will go thorugh the same ports if the engine is not running as well. The effectiveness of the flush will depend on your water pressure.
I hope this helps!
Happy Boating,
LucyLu
I tried using the freshwater flushing device on my Yamaha instead of the flush muffs. Great idea, especially at night when my neighbors don’t want to hear the engine running. However, water did not come out the pee hole (or whatever you want to call it). I didn’t see it happen on your video either. Should I expect this to occur using this flushing technique? Was the water pressure from the hose to low? How can I be sure that water actually traveled through the upper passages instead of taking a path of least resistance and simply running down and out? What is an appropriate water pressure and what is too high? Does Yamaha have a diagram showing the path of water flow when using the freshwater flushing device for skeptics like me?
Hi ML,
Good Question!
Getting down to business…..The first question is does your engine “pee” (vernacular for stream) while the engine is running in the water?
If your engine DOES “pee” while running the engine (in the water) and NOT while you are using the hose on the flush kit then it most likely a lack of water pressure or a clog in the system. IF your engine DOES NOT “pee” while in the water then you may be experiencing a clog or impeller (water pump) issue. If this is the case I suggest you take your engine in for service.
Honestly when flushing your engine there is really never too much water pressure while using the flush kit. As a matter of fact the greater the pressure the better the flush of your engine. I hope that I answered all your questions.
Good luck and thank you for reading our blog.
My best,
LucyLu