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FLUSHING 225hp Honda in harbor slip (salt water) not a 100% flush?

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805bigdrake

New member
I KEEP MY BOAT IN A SLIP - SALT WATER. (IMPORTANT POINT)


Honda 225hp engine. Year 2011



I have my 225hp Honda outboard (2011) serviced every 100 hours. Yet, my ‘OVERHEAT ALARM” went off (light and alarm) nearing the 100 hour mark last week. Had boat trailered by Honda certified dealer to their shop and they told me it was most likely a “lazy thermostat” issue and replaced them. I went out the next morning and after 10 minutes the "OVERHEAT ALARM” went off once again so I called the certified Honda mechanics and they told me they were stumped and they would come and trailer it back to dealership and find out what’s going on. Two days later they called me and said that they removed the “cover behind the thermostats”(?) and it was plugged with salt and they were absolutely sure that was the problem and they were correct. Boat now runs awesome. Very happy.

So, when I flush my engine after EVERY use in my harbor slip (using hose connector so I cannot start the engine says manual) it’s apparently NOT a 100% flush? What can I do since I do not own a trailer? Is it possible to remove the thermostats while in slip and (not every time, but once in a while) then squirt in some “Salt Away” or something similar and let it sit for a couple of days? Would that do it? Or, do I pay to have the dealership remove the cover plate behind the thermostats and clean it out every once in a while? Is it costly (dealership did not charge me) to remove the cover plate behind the thermostats? Has anyone experienced these issue as well?


Any guidance is appreciated.

Thanks,

Big Drake
 
The best is to rig up a platform of sorts so you can put flushing ears on your motor. You can safely run it tilted up. If that motor is not flushed properly you'll end up destroying it with corrosion.
 
So the reason you can't start it (manuals directive) is that the fresh water is not actually properly cooling the motor and/or it would require the motor be tilted out of the water to prevent saltwater entering the intake, correct? I think it would be ok to occasionally tilt it up and run it briefly with the hose attached to the adapter. My assumption, is that connecting the hose via adapter at the flush port, allows for the water to circulate the cooling channels in the block under direct pressure from the hose without having the motors vacuum push it through the system, but it still reaches all the same channels in the system. Now it is possible that in the absence of vacuum there will be areas that do not get flushed and could over time become blocked. I would talk to a mechanic that knows exactly how your motors cooling system behaves in the presence of vacuum and without. You can also compare the volume of fresh cooling water expelled from the tell-tail. Does it match the volume of seawater expelled when the motor is running? If they are similar then it might be close to 100%, but again, find a person that is an expert with these motors to be sure.
Is it possible to reach the intakes if you back your boat into the slip? If so, just back in and place the square ears over the intakes to flush. I'm pretty sure it's the square ears that work better than the round ones, but this may be motor specific, get both, they're cheap.
Mike
 
siluetae137 said:
So the reason you can't start it (manuals directive) is that the fresh water is not actually properly cooling the motor and/or it would require the motor be tilted out of the water to prevent saltwater entering the intake, correct? I think it would be ok to occasionally tilt it up and run it briefly with the hose attached to the adapter. My assumption, is that connecting the hose via adapter at the flush port, allows for the water to circulate the cooling channels in the block under direct pressure from the hose without having the motors vacuum push it through the system, but it still reaches all the same channels in the system. Now it is possible that in the absence of vacuum there will be areas that do not get flushed and could over time become blocked. I would talk to a mechanic that knows exactly how your motors cooling system behaves in the presence of vacuum and without. You can also compare the volume of fresh cooling water expelled from the tell-tail. Does it match the volume of seawater expelled when the motor is running? If they are similar then it might be close to 100%, but again, find a person that is an expert with these motors to be sure.
Is it possible to reach the intakes if you back your boat into the slip? If so, just back in and place the square ears over the intakes to flush. I'm pretty sure it's the square ears that work better than the round ones, but this may be motor specific, get both, they're cheap.
Mike
Click to expand...
The reason you can't start it on the factory atrachment is because there is no water running through the waterpump.The factory flusher failing has nothing to do with vacuum, it simply doesn't circulate properly because it's a cold flush and I have seen many engines flushed this way with bad corrosion and blockages in the thermostat area. Thus the preferable method being to make a plan and use flushing ears with a running motor in order to get the thermostats open for a full clean out
 
Ok, so when I start my motor in the water it too is a cold flush until the motor runs long enough to open the thermostat. I think the confusion is how much of the motor is accessed. Does the water moving via the flush port simply bypass the thermostat altogether even if it's open? Or is it simply stopped at that point because the thermostats closed? See this is what I've never been able to fully understand, if the motor is running with the water connected at the flush port then does it still not reach the thermostat? Because the thermostat will open when it gets to temp and if water is circulating then it should pass through the thermostat as well, would it not? If it does then flushing via the flush port with the motor tilted and running is the same as running it in the water - minus the pickup tube section from lower unit to the motor. But I'm probably totally missing something...
 
What Ian said. Ideally you run the motor in a test tank until stats open. If using muffs (required if you are at the dock), you must have adequate water pressure to keep from overheating. The flush ports do not adequately flush these motors.
 
No I agree with you Ian & Deux, and I flush mine in a tank each year - twice - but it's a subject I always pick other boaters and mechanics brain on. Because as much time we spend working on these motors, reading about everything ( in often too much detail), discussing, sleeping - dreaming..all that time acquiring knowledge, and there are still niche topics to explore and even the ones we universally accept, still have nuances being debated and discovered.
Mike
 
Several years ago when I had my boat pulled for maintenance in my driveway, I removed the T-stats and hooked up the flushing hose. It took almost 10 minutes for water to finally get up to the bottoms of the t-stat seats, and it had no pressure whatsoever. I concluded that the flush port was a lousy way to flush the engine, but trying to flush the engine with muffs after every usage is not practical because my boat is parked on a lift over the water. What I did was run a 3/4" hose (which provides a good bit more pressure) directly from my well pump to the end of my pier and plug in a quick disconnect hose to the flush port as soon as the boat is on the lift and still hot. See the attached set up of how I have it set up for quick flushing. That seems to work reasonably well.

Once the t-stats close, the flush water is diverted to the pressure relief valves.
 

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chawk_man said:
Several years ago when I had my boat pulled for maintenance in my driveway, I removed the T-stats and hooked up the flushing hose. It took almost 10 minutes for water to finally get up to the bottoms of the t-stat seats, and it had no pressure whatsoever. I concluded that the flush port was a lousy way to flush the engine, but trying to flush the engine with muffs after every usage is not practical because my boat is parked on a lift over the water. What I did was run a 3/4" hose (which provides a good bit more pressure) directly from my well pump to the end of my pier and plug in a quick disconnect hose to the flush port as soon as the boat is on the lift and still hot. See the attached set up of how I have it set up for quick flushing. That seems to work reasonably well.

Once the t-stats close, the flush water is diverted to the pressure relief valves.
Click to expand...
I value these type of personal accounts, thanks Chawl_man!

Why did it takes 10 minutes for water to reach the thermostats from the flush port? The only possible factors that make sense to me would be particulates or insoluble salts impeding the flow, and/or incomplete vacuum diverting flow. Drawing on Chawk_man's conclusion that it's not an effective flush mechanism, one would assume that a physical impediment was not the issue with the engines flush system. I am also hesitant to attribute lack of pressure the main cause. This is the universally accepted reason, or most often heard at least, where low flow is reported due to the lack of pressure at flush port and the fact that the water pump is not pushing water through the system. Which I agree with, but in a different way...for me its more about vacuum. Regardless, we can agree the flush port is not adequate due to one or more of the following:

1. Flow gets diverted at thermostats when they are closed,
2. Flow dissipates quickly due to insufficient pressure at source - the water supply line connected to flush port is not adequate, and
3. Overall low flow due to an incomplete vacuum between flush port and cooling system channels.

Although changes to the supply line and preventative maintenance can mitigate #1 & 2, it's the third mechanism that is truly inherent to the engines construct. Which brings me back to what in this design provides enough vacuum for the coolant to flow? The rotation of the impeller in the pump chamber alternates between pressure and vacuum constantly at a fairly high rate, something a garden hose doesn't do - and over-pressurizing the hose still won't give you flow until vacuum is introduced.
So is there a convenient way to get vacuum into the system during a flush port flush with thermostats open???
 
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