Decarbonizing by spraying water mist into the intakes while running?

777funk

Petty Officer 2nd Class
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Jan 12, 2015
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This has become fairly popular with 4 strokes and it works to steam clean the cylinders. I'm curious if it'd be a bad idea on a 2 cycle since on a 2 stroke you have the intake fuel mix as the lube. Obviously water is not what we're after for lube. The water mist is quickly turned to steam and exhausted but I'm still a little concerned here. Maybe I'd try it on an old junk chainsaw or weed eater as a test dummy.

Any insight into this? Anyone tried it on a 2 cycle?
 

pnwboat

Rear Admiral
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Oct 8, 2007
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I'm not an expert by any means, but I don't think it would be a good idea because in a 2 stoke, the engine bearings (crankshaft and connecting rod) are lubricated by the oil in the incoming fuel mixture. 4 strokes don't have this problem since the incoming fuel mixture is pretty much isolated from the pressurized oil system that supplies oil to the engine bearings.
 

mla2ofus

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Dec 30, 2008
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The fuel air mix has to first go thru the crankcase on a 2 stroke and I don't think water in there would be a good thing.
Mike
 

Jiggz

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Oct 23, 2009
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It can be done but very carefully and obviously not recommended for the inexperienced. As you mentioned, due to lack of sole separate lubrication system, a two cycle engine can easily be destroyed (in a matter of seconds) due to lack of lubrication. So far the popular ways of doing this is with the use of seafoam additives. There are two ways to do it. Personally, I soak the cylinders with pure seafoam by spraying (3~4 sprays, aiming on all sides) it directly into the plug hole in each cylinder and manually rotating the flywheel to distribute it (of course you have to remove all plugs). Keep the engine full upright so as to prevent the seafoam from draining into the crankshaft alleys. Re-install the plugs and leave it overnight. Keep some of the seafoam in the spray bottle (any spray bottle as long as it can hold about 1/2 quart or less).

The next day make preps to start the engine. Leave the upper cowl off and remove the air covers on the carbs. Make sure nothing loose can get sucked in to the carbs while engine is running. Place a plyboard or some flat sheet metal (like those one used to catch oil drip under the car) under the LU spotted for the exhaust. This is so as to see how much carbon is blowing out of the exhaust when you de-carbon which will tell you when to stop. Start engine and warm it up, about 2~3 minutes. Using the tie bar or the control tower on the carbs' linkage rev up the engine but do not exceed ~3K rpm in short and intermittent fashion while spraying (a single spray of mist seafoam into each carb. Start with the top carb and intermittently switch with the bottom ones. Then watch how much carbon is spewing out of the exhaust. If exhaust is heavy on carbon, continue doing the same until it lightens up. Do not wait until the exhaust is totally light, as this is very dangerous for the motor. I'd say when the carbon dust coming out of the exhaust is like 50% less than the initial one, then it is time to stop.

Put everything back together and then pour in the left over seafoam into the fuel tank in right proportion, read directions. The above process is best done in warm weather that doesn't mean it cannot be done in cooler weather.

The other way of doing it is just to spray the cylinder with seafoam, soak it and treating the fuel tank with seafoam. Take the motor on the water, warm it up and run at WOT for about 5~10 minutes.
 
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bilge rat jim

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Jun 28, 2012
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Just get a small jug of Chevron Techron+ and run a couple of treatments thru your outboard. Follow the instructions on the label- in this case "more" is not "better". It is a bit more expensive than water :lol: but in my experience is one of the few engine treatments that actually does something.
 

Jiggz

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I just need to put out that when "steam cleaning" an engine even with 4 strokes, the water is not mixed with the fuel. Instead it is sprayed mist into the carbs. This is a practice in the old carbureted engines. With fuel injected engine this practice is basically obsolete although you can try spraying the water into the air intake which most likely will be filtered by the air filter unless you can find a way to spray it after the air filter.
 

777funk

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Jan 12, 2015
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I just need to put out that when "steam cleaning" an engine even with 4 strokes, the water is not mixed with the fuel. Instead it is sprayed mist into the carbs. This is a practice in the old carbureted engines. With fuel injected engine this practice is basically obsolete although you can try spraying the water into the air intake which most likely will be filtered by the air filter unless you can find a way to spray it after the air filter.

With a car or truck many guys use one of the vacuum lines dropped into a water bottle. Water gets drawn in a little at a time.

I think you're probably right on it being a very sensitive operation with a 2 stroke. I'm not sure I'll risk it with my new to me old outboard.
 

jerryjerry05

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May 7, 2008
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17,923
Not in any outboard I own.!!

If your worried about a de-carb, Mercury's Powertune or OMC's Enginetuner.Yam makes one too.
Seafoam= snakeoil.
Follow directions.
The after it's decarbed, remove the plugs and spray in till you think the piston top is covered.
Let it set for 24 and then rotate 180 and add more and let set for 48.

This will get most out.

BUT!!! If there is any real difference in compression#s then you need to re-ring.
Oh yea do a comp test first.
That will tell the condition of the cylinders.
 

gm280

Supreme Mariner
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Jun 26, 2011
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I personally would not spray water into any 2 cycle engine I own :nono: but I hear Seafoam used all over these forums. And I do remember years ago mechanics using transmission oil/fluid thorough the carbs on engines. Of course it looked like the vehicle was burning down from all the smoke it produced. But I think the Seafoam would be the better suggestion. I mean after all that is what it is made for... JMHO!
 

gregmsr

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Sep 20, 2006
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I used to think Seafoam made my motor run better....maybe the wife had lost a couple pounds?
 

jerryjerry05

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I did a test with Mercury Powertune and Seafoam.
I put a piston(2) in a couple ounces of each.Seafoam and Powertune.
The next am the PT had the carbon melting off the top of the piston.
The Seafoam did nothing.
I put that piston in the PT and again the next am the PT had melted the carbon off the piston.

But NO amount of PT and heat or anything will get the carbon from under the rings.
I understand the Seafoam is a good gas line antifreze.
 

Justinde

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Dec 11, 2010
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431
The last time I saw that was about 20 years ago when we put an old Volvo with twin side draft carbies on it. We ran it up to 180k/hr ( stationary) on the dyno, and my teacher had a 2 litre coke filled with water. When the exhaust was red hot, he tipped slowly so to let the carbs suck water in. when the engine missed a bit, and spat out a shitload of black crap out the exhaust, he'd back off and start again. It really was artwork. It is also something I would never try, not even on my lawnmower. I just thought I'd share a story;-)
 
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