I guess a lot of us have heard how trickling water down your intake with the engine running will shift carbon deposits from the piston crowns.
Some have advocated using seafoam or other proprietary cleaners.
I've done it myself for longer than I want to remember, and it works, I've had cars running better as a result of this treatment. I don't know if I shortened or prolonged the life of the engines by doing this, to properly test this would take more resources than I have.

I've wondered how it works, here's my theory, at least for water as that is all I've ever used;
When the water droplets hit the piston crown they almost instantly turn to steam, and it is cavitation as result of this that breaks up the carbon, the turbulence of combustion sees the particles blown out through the exhaust valve.
Cavitation is a major enemy of plain bearings, most engineering teaching establishments will have examples and pictures of cavitation damage on display, but I think it is a good way of shifting carbon deposits on an old engine in the same way as it causes pitting in bearings.

It may be that some chemical reaction takes place during the combustion process between the water and carbon, perhaps the gasoline and air also play a part. I haven't studied chemistry properly for 40 years but I think it unlikely.
I don't think it is steam pressure that shifts the carbon, if you were to take a piston with carbon deposits and try to remove the carbon with a conventional steam cleaner I don't think it would work well if at all. Steam cleaning works by blasting a controlled jet of very hot vapour to separate dirt from whatever you are cleaning, in a combustion chamber that doesn't happen.

That's my theory in a nutshell, I'm happy to be proved wrong (or right).
Anyone else got some ideas?.

Roger.

 

Liquid can't compress so it kind of makes a small explosion when heated and shoved down the cylinder and blast's the carbon off.

 

My theory is that the water is turned into super heated liquid under pressure during the compression stroke. Since the water is compressed, it cannot turn to steam. During the power stroke (and probably exhaust), the water gets the room to evaporates to steam in a violent explosion of its own. The result is a steam blast to the carbon, which loosens it up.
I am not a scientist, but it makes sense. And after seeing how an explosion from an overheated, overpressurized water heater can level a one story home, I really saw the violent energy in water turning to steam. I think i remember like a 1:15 ratio between a part of water and it's steam equivalent.

 

It's not the best thing to use,but it works i learned that trick years ago from an old boss on an engine that was knocking.You pour more than a trickle,and no it's not a chemical reaction.Imho

 

my theory is that the temp. difference between the hot carbon and the relatively cold water causes the carbon to fracture and get blown off during the combustion cycle.

i've always used gm top engine cleaner liquid, works like a dream-stinks/burns the eyes like a ****. of course, i'm sure they've discontinued it due to epa regs. i'd go the seafoam route though(or naptha) as this will also penetrate to the ring area and possibly free them up, if they're sticking.


bill

 

I used to pour a pint to a quart of Marvel Mystery oil in a full tank of fuel every so often. That works well.

 

But how and why does it work?.

Roger.

 

It's a mystery.

 

Yeah, didn't see that answer coming.

 

Makes sense Bill.

My nephew has just completed his Masters degree in mechanical engineering, I'll ask him what he can come up with next time he comes round to have his bicycle fixed.

Roger.

 

Lol, rusty. That made me actually laugh out loud!

 

x2!