Static vs Running outboard flush

[Capt’nKarl]

I’ve seen both of these methods used to flush out salt water from the engine. Considering the engine is warm and the boat is out of the water Is one method better than the other?

 

[knotflying]

The static flush does not do the entire system. It only does above the impeller. A running flush will do the entire system.

 

[fmstuart]

When I have flushed the engines, I see water coming out of many areas, including the props. Wouldn’t that indicate the fresh water gets past the impeller as well?


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[BB marine]

The static flush is worth while. It is easy and quick. It does flush the internal water jackets of the block. It does do a better job if the block is still Hot/warm to help flush the salt water deposits that crystalized during the operation of the engine that day. If the boat is used frequently a static flush is a good method of keeping the block flushed. As Mike stated the block is all that is getting flushed.

Running flush is the best way to flush an outboard. If it is practical to do on a lift I would use this method. On a trailer there is no question it is the best way to flush. For a boat left in the water running flush can be difficult. Running flush disburses water from the gear case to powerhead then disburses the fresh water in the midsection. The running engine will maintain a higher temperature helping to remove the crystalized salt deposits in the block along with higher exhaust temperature in the midsection.
No flush - not good
static flush - good
running flush - Better
My opinion !

When I have flushed the engines, I see water coming out of many areas, including the props. Wouldn’t that indicate the fresh water gets past the impeller as well?

No, the water is falling out of the block and draining out through the prop hub. The engine gets water for cooling from the water pick-ups in the lower unit. The water is pulled up Via the water pump ( housing and impeller) then sent to the block through a water tube. The blocks water passage ways are filled with water and once filled the water exits the exhaust cavity . The cylinder water jackets and heads water jackets have thermostats to help maintain a higher temperature for combustion. Some of the water by-passes this and is used for exhaust cooling. Think of the water flowing from the static flush of finding the path of least resistance to exit. That would be the exhaust cavity not the water tube leading to the pump.

 

[Brian98133]

Not sure about it 'not flushing the entire system'. Do we have facts that back that up? IMO, it would be unwise for Yamaha (or any OB mgfr) to recommend a system that would leave raw water un-flushed which would lead to premature deterioration of their product.

In talking to my Yamaha service folks (yes, I was unsure of the static flush at first), the entire system gets flushed on both sides of the impeller, which is why Yamaha tells you not to run the engine while performing the static flush or there may be damage to the system.

This makes sense to me, given that every orifice on the engine has water flowing through it during the static flush. Also, in my experience, the initial run of water is very warm when exiting the engine (and splashing all over me!), telling me that the water has run its course through the cooling channels of the engine.

I am satisfied that the static flush is very sufficient. But I'm not an 'expert'...

 

[ixlr8]

In talking to my Yamaha service folks (yes, I was unsure of the static flush at first), the entire system gets flushed on both sides of the impeller, which is why Yamaha tells you not to run the engine while performing the static flush or there may be damage to the system.

I was told the reason not to run the engine during a 'static' flush was due to the pump impeller not getting water on it's inlet side and you would damage the impeller due to lack of water.

 

[Brian98133]

"I was told the reason not to run the engine during a 'static' flush was due to the pump impeller not getting water on it's inlet side and you would damage the impeller due to lack of water.[/quote]"

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Very possible... as I said, I'm not an expert. However, if there is no water getting to the pickup side, why would there be so much water flowing out of the pickup ports (where you would put your ear-muffs for a running flush) during a static flush?

Water flowing out of every port is what leads me to believe the entire system is being flushed. Now my OCD brain is going to force me to research this further! :roll:

 

[fmstuart]

Keep researching!!!!! We appreciate it.


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[BB marine]

Not sure about it 'not flushing the entire system'. Do we have facts that back that up? IMO, it would be unwise for Yamaha (or any OB mgfr) to recommend a system that would leave raw water un-flushed which would lead to premature deterioration of their product.

In talking to my Yamaha service folks (yes, I was unsure of the static flush at first), the entire system gets flushed on both sides of the impeller, which is why Yamaha tells you not to run the engine while performing the static flush or there may be damage to the system.

This makes sense to me, given that every orifice on the engine has water flowing through it during the static flush. Also, in my experience, the initial run of water is very warm when exiting the engine (and splashing all over me!), telling me that the water has run its course through the cooling channels of the engine.

I am satisfied that the static flush is very sufficient. But I'm not an 'expert'...

In my post I am agreeing . The flushing system that Yamaha has installed for static flushing will work good. No question. Yes the facts are correct and you actually stated them. " Yamaha tells you not to run the engine while performing the static flush or there may be damage to the system" The damage is to the water pump impeller it will running dry, because there is no water at the pump.


Flushing the engine using the static flush works. That is why it is there. Running the engine with a flushing adapter works. Running the engine with a flushing adapter when convenient on a trailer or on a lift would be a preferred way of doing it. It always has been. With the popularity of larger outboards installed on larger boats the flushing of the past via the flushing through the lower unit is not practical in many cases. The outboard manufactures incorporated a way to static flush which allows for the POWER HEAD to be flushed. You have experienced this. You felt the initial warm water as it heat syncs the block. The water eventually gets cold. It's still flushing the block.

Now think of flushing the engine with it running with fresh water flowing through as it gets heated up and the hot exhaust pressure dispersing the fresh water throughout the complete exhaust cavity and midsection. The water is being pumped from the water pump in the lower unit. The complete cooling system and exhaust system are being showered with warm fresh water. This is the preferred way of flushing when practical.

Your Yamaha dealer may have a different opinion. I would bet they run a lot of engines using the old fashion flushing devise at their shop.

There is no reason not to be satisfied that the static flush is very efficient. It is good !

 

[Brian98133]

"In my post I am agreeing . The flushing system that Yamaha has installed for static flushing will work good. No question. Yes the facts are correct and you actually stated them. " Yamaha tells you not to run the engine while performing the static flush or there may be damage to the system" The damage is to the water pump impeller it will running dry, because there is no water at the pump. "

I knew (and appreciate) that... I was actually referring to the previous post 🙂

"With the popularity of larger outboards installed on larger boats the flushing of the past via the flushing through the lower unit is not practical in many cases. The outboard manufactures incorporated a way to static flush which allows for the POWER HEAD to be flushed. "

Very good point I hadn't considered! :idea:

"Now think of flushing the engine with it running with fresh water flowing through as it gets heated up and the hot exhaust pressure dispersing the fresh water throughout the complete exhaust cavity and midsection. The water is being pumped from the water pump in the lower unit. The complete cooling system and exhaust system are being showered with warm fresh water. This is the preferred way of flushing when practical. "

Thank you for this... it makes sense. We are on the hard when not boating, so we have the ability to do either method. We travel "up river" to the homeport, so it's pushing brackish water the last 10 min or so before being hauled out. That probably helps a bit, but I don't believe it's fully sufficient, so I do a full flush after each outing as if we were hauled out of full salt.

While static flushing is probably sufficient, after your words about letting the system heat up, thermostats opening, etc., it does seem like it might be the preferred method.

My main concern now is how to go about this? The 200F seems to have numerous pickup points on the lower unit, and in my limited research so far, it seems like the standard 'muffs' that I had for my old I/O outdrive may not be the best solution because Yamaha recommends that "all inlet ports" get water. There's a 'flush bag', but it recommends removing the prop (for safety reasons, I assume), and that seems like more work than is necessary. There is another mention of a 'lower unit specific flush muff', but I haven't found what that is yet.

Others have talked about putting duct tape over any inlet port not covered by the muffs... but that seems hokey.

More research needed! :ugeek:

Edit: I don't seem to be getting the 'quote' thing right? Others quote and it shows up with a tan background... Oh well... :cry:

 

[BB marine]

While static flushing is probably sufficient, after your words about letting the system heat up, thermostats opening, etc., it does seem like it might be the preferred method.

That is my opinion. Yamaha is also recommending your method is sufficient. The key component is the engine is getting flushed.

My main concern now is how to go about this? The 200F seems to have numerous pickup points on the lower unit, and in my limited research so far, it seems like the standard 'muffs' that I had for my old I/O outdrive may not be the best solution because Yamaha recommends that "all inlet ports" get water. There's a 'flush bag', but it recommends removing the prop (for safety reasons, I assume), and that seems like more work than is necessary. There is another mention of a 'lower unit specific flush muff', but I haven't found what that is yet.

With the dual pickup gear case the simple throw the muffs on and flush requires covering the lower pick up to prevent air from reducing suction and then reducing water flow. The simple fix is a roll of shrink wrap tape on hand. Covering the lower pickup screens with tape. Seems a bit shade tree but it works. If I was going to use this method of flushing with a dual pickup gear case I would fabricate an attachment. There is a company in Sarasota FL that makes an aftermarket devise. In the mean time based on your usage in brackish water and then a complete flushing as per Yamahas recommendations using static flushing. As you said before.

I am satisfied that the static flush is very sufficient.

You are correct.

 

[nboyer]

I saw this post about a week ago and paid close attention to where the water exists when performing a flush via the flush port on the engine this past weekend (2020 R-23). I have my boat stored in a boatel and every time when I return back, I have the marina put the boat on a wash rack where I flush the engine and wash down and dry the boat. I did noticed that water does exist the water intake on the lower unit (the one that has the black screen/filter screwed on) as well as the other usual places. Cheers! -Norm