Tow valves for flushing

[Scoop]

Looking for some engine flushing advice. I have completely read the tow valve thread and have a good handle on the whole towing single engine issue - if it were only the occasional tow/single engine issue I would go with clamping off the line since this (hopefully) may never be required.

I am more concerned with flushing the engine after salt water use. When I flush the motor after use and it is warm no water exits the through the hull side drains - all water exits via the various stern drains. If I start the engine cold it will flow through the hull side drains for a few minutes and then it stops. Perhaps diverted via thermostat?

I just got a new boat and don’t really want to modify it unless it is really needed. Here are some questions for the wise and experienced jet boaters:

Will flushing on a lift out of the water with salt away be adequate long term? Why would Yamaha design the cooling system this way if does not thoroughly flush the motor?

If I install the tow valves I will probably put them aft next to the clean out plugs but am concerned about accessibility.

For the guys using the clean out plug placement is it possible to install them via the removable oval cover (see photo) or is worth it to remove the much larger screwed in rectangular panel.

Finally, anyone have any long term salt water experience with the stock flush setup? Thought?

Thanks Scoop

 

[haknslash]

You won't have water come out your pissers on the side of the boat unless you have high water pressure at the hose. I adjusted mine to near 70 PSI and it flows out of the pisssers.

Yes flushing on the lift with salt away would be fine long term. If you wanted to flush while in the water you will need the tow valves installed so you can shut off the water cooling pickup that's located inside the jet pump housing.

I understand the whole it's a new boat and don't want to modify it but the reality is you're going to eventually want to make it your own so you might as well accept it now hehe. It's a boat so expect to modify and spend $$.

 

[swatski]

View attachment 79742 Looking for some engine flushing advice. I have completely read the tow valve thread and have a good handle on the whole towing single engine issue - if it were only the occasional tow/single engine issue I would go with clamping off the line since this (hopefully) may never be required.

I am more concerned with flushing the engine after salt water use. When I flush the motor after use and it is warm no water exits the through the hull side drains - all water exits via the various stern drains. If I start the engine cold it will flow through the hull side drains for a few minutes and then it stops. Perhaps diverted via thermostat?

I just got a new boat and don’t really want to modify it unless it is really needed. Here are some questions for the wise and experienced jet boaters:

Will flushing on a lift out of the water with salt away be adequate long term? Why would Yamaha design the cooling system this way if does not thoroughly flush the motor?

If I install the tow valves I will probably put them aft next to the clean out plugs but am concerned about accessibility.

For the guys using the clean out plug placement is it possible to install them via the removable oval cover (see photo) or is worth it to remove the much larger screwed in rectangular panel.

Finally, anyone have any long term salt water experience with the stock flush setup? Thought?

Thanks Scoop

I struggle with the same question on a tow valves install. My 0.02:

There are a lot of these boats running in salt w/o the tow valves installed, extremely well maintained.
As previously stated those tow valves are only required for flushing if flushing in the water (in a wet slip).

Yes, closing tow valves will push more water through the engine cooling system. However, at the same time will reduce flushing the pump/impeller assembly dramatically as water will just drip down the exhaust (outside). Not sure what the effects might be long term but I think you would want the pump flushed as well in salt.

Also keep in mind those "pee holes" are just indicators that in most cases, when flushing on a hose, will not produce a stream which is okay as there is still water/salt-away flowing fine through the cooling system.

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[MidnightRider]

For the guys using the clean out plug placement is it possible to install them via the removable oval cover (see photo) or is worth it to remove the much larger screwed in rectangular panel.

No its not possible to install the valves without removing the larger panel that is screwed down (unless you're an alien with octopus like arms) but they are accessible through the oval cover to operate once they are installed. I did look through the oval cover ahead of time to make a mental note of where on the hose I wanted to install the valve to ensure the easiest accessibility as possible. Also, I'll note I didn't have to remove any water boxes or hoses to install the valves, only connections necessary to the remove the panel.

 

[Frank Marshall]

From what I think your prospective is (no mods, they're a pain) I would flush once up on your lift. Along with the engine, be sure to get as much of the jets inside and out as possible, from both sides to remove the salt from them as well. Doing this on a lift, I would recommend Salt Away as it doesn't even require a MSDS sheet, it's non-hazardous according to the manufacture. http://www.saltawayproducts.com/

 

[Gym]

I have my tow valves (I prefer to call them bypass valves as I never want to need to be towed) installed under the clean out cover accessed through the ports.
I close the valves for every flush whether on the trailer or in the salt water. By doing so you will get water out your pissers as it forces more water/Salt Away into the upper cooling passages of the engine. If you're sitting in salt water while flushing your pumps aren't going to be getting a flush anyway. I have no problem reaching my valves from my access ports.

 

[Philip]

I installed my valves in clean out area and mounted on top of muffler with a loop. I’m thinking I may have issue w self draining now as it’s higher location

 

[Philip]

Thoughts?

 

[buckbuck]

Yes you will have an issue.
There are some of us that purposely have not installed valves due to our concern about a restriction in the line. Others feel the ability to easily isolate the engine cooling is worth the risk.

 

[haknslash]

^^^ That's why I liked the radiator hose clamp option some people chose to go with. Use it when you need it but doesn't affect flow the other 99% of the time you don't need it

If I were to install tow valves I would have them no higher than the rest of the system. I'd probably install them in the engine compartment near the "Y" like in the FAQ install.

 

[Philip]

Reinstalled it and put it in line so no issues.

 

[buckbuck]

That is where I have seen others put them.

 

[WREKS]

Please, excuse me if I am covering information previously covered!

I have an issue with the utilization of flush valves, alternately called tow valves. Buckbuck's study on cooling system psi vs. rpm indicates that at no wake speeds, about 2400 rpm or 3mph, psi does not event register. At 10,000 rpm, psi gets up to about 26.5. If these measurements are within 15% accurate, the cooling system never gets much beyond 30 psi at the intake..

Now what happens if the system design pressure gets replaced by a system with higher pressure?

Is there a maximum water pressure above which the gaskets can no longer function properly?

 

[swatski]

Please, excuse me if I am covering information previously covered!

I have an issue with the utilization of flush valves, alternately called tow valves. Buckbuck's study on cooling system psi vs. rpm indicates that at no wake speeds, about 2400 rpm or 3mph, psi does not event register. At 10,000 rpm, psi gets up to about 26.5. If these measurements are within 15% accurate, the cooling system never gets much beyond 30 psi at the intake and drops as cooling water is diverted to the oil cooler, manifolds, cylinder head and cylinder water jackets. Nowhere in the cooling system will the water pressure be as high as it is at the intake.

Now what happens if the design system gets replaced by a higher pressure system?

Is there a maximum water pressure above which the gaskets can no longer function properly?

I can not answer this but am watching!
I am very much interested in being able to increase, or at least not diminish, cooling water flow through the system while adding tow valves.

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[WREKS]

Reason I am putting this out there is because I had milky oil from a small erosion channel in the cylinder wall between a water passage and the #1 cylinder. To put it in other words. Can higher pressure flushing water compromise the cooling system and cause unintended circumstances?

 

[swatski]

Reason I am putting this out there is because I had milky oil from a small erosion channel in the cylinder wall between a water passage and the #1 cylinder. To put it in other words. Can higher pressure flushing water compromise the cooling system and cause unintended circumstances?

Huh. IDK. Personally, however, I'm more worried about insufficient and potentially uneven cooling in this system due to sediment or corrosion, potentially leading to heat related head cracks. Total speculation though, and yes - too much cooling is also not a good thing.

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[Beachbummer]

If you want to see the difference you could use a vise grip or hose pincher to block the hose to try it out.

 

[WREKS]

If you want to see the difference you could use a vise grip or hose pincher to block the hose to try it out.

Thanks Beachbummer, I know it works. I am just afraid it may overwork and breach the head gasket between the cylinder wall and a cooling passage. Here is a place where water, rather steam, got into my cylinder and caused "milky oil syndrome." This is located on the exhaust side by Cylinder 1 on my SX230HO. The inked pic points to a just visible cavity in the cylinder wall. I know the pics are not that good.

 

[2kwik4u]

Thanks Beachbummer, I know it works. I am just afraid it may overwork and breach the head gasket between the cylinder wall and a cooling passage. Here is a place where water, rather steam, got into my cylinder and caused "milky oil syndrome." This is located on the exhaust side by Cylinder 1 on my SX230HO. The inked pic points to a just visible cavity in the cylinder wall. I know the pics are not that good.

I would highly doubt that higher pressure from cooling water would cause that kind of damage. Even 200psi water won't do that to aluminum. That looks like a cavitation or aeration burn. Possibly carbon deposits along the cylinder/head interface getting very hot and essentially creating a localized boiling point that, over time, shows the same erosion as cavitation.

There are other possibilities as well. Additional pressure is accompanied by additional velocity when looking at fluid flow through a given area. Localized accelerations of fluid could lead to erosion of the metal of very long periods of exposure, assuming there was something in the water to make it abrasive (sand, or other suck grit). This is the same concept as a water jet cutter. High pressure differential is used to accelerate water with cutting agents across the surface of a material to cut it. I could see that possibly being the case here, however the material removal appears to be non-uniform, and extremely localized. "waterjet" type erosion would more typically show as overall thinning of the walls, and not nearly as pinpoint as what is shown here.

Pressure alone won't hurt the gaskets. Combustion pressures are significantly higher, orders of magnitude, higher than cooling water pressures. The pressure must be combined with increased flow velocity to erode the metal like that. i.e. the valves are most likely NOT the cause of that sort of erosion. I would suspect bad luck with an imperfect casting in that area is more likely.

 

[BrentEB]

Hey WREKS. Help me out here - it looks like the cavity is in the head rather than block/cylinder. Am I seeing it right? Probably corrosion. Otherwise I don't think the cooling water pressure could get high enough to breach the head gasket.

On my boat (2013) there is a check valve to prevent the coolant in the block from draining when the engine is shut down. Most likely to keep the engine from overheating just after shut off. If the block cannot be flushed the passages will begin to plug, which was my problem. I can easily imagine that could have caused your problem as well.