Piston help....

[Meat-Run]

Pulled plugs on my trusty old Mariner and looked inside and noticed a bunch of carbon build up or burnt pistons on all 4 cylinder's. I know theres carbon cleaners for auto that you put in but with outboards sitting a different way is there something out there to do a "top end" cleaning??? Hope a marine mechanic or someone familiar can help?

I have pictures on my cell phone taken right into the spark plug holes, kind of blurry and when I post Iphone pictures they turn them sideways or upside down is it worth trying to share?

It's been running fine, no low-end or top-end performance issues but if its only carbon I would like to clean it out.

Thanks for any input you share.

Meat Run

[boatfixer]

Go get a can of omc/BRP Engine Tuner. It's made just for that. Just follow the directions on the can

[Meat-Run]

Go get a can of omc/BRP Engine Tuner. It's made just for that. Just follow the directions on the can

Can I get that at Napa or mills fleet?

MR

[boatfixer]

It's a dealer product. There is another one from mercury/quicksilver called Power Tune.. Basically the same stuff. I've used engine tuner for 20+ years and its a very effective combustion chamber cleaner. Removes carbon from pistons and rings. I pretty much use it as part of a tune up.

[Meat-Run]

Thanks for the help, I'll contact a marina to find the recommended product.

MR

[JohnMickish]

Yamaha ring free is another option. Follow the directions to a "T" no matter which way you go.

[Meat-Run]

Well I was just over at Napa picking up some other parts and was informed of the Sea-Foam Cleaner, I think its the same product you use to fog your motor but a little more concentrated, I might give that a try.

MR

[boatfixer]

It's not the same as fogging oil. You don't to use a fogging oil as it coats the inside. The cleaners and carbon removers are what you need.

The ring free is a good product as well. That, you add to the gas and it works slower. It does work, but over a period of time. I've raised compression as much as 15 psi using engine tuner in just one dose.

[BoxMN]

Boatfixer, when you use the power tune type thing, or engine tuner, do you end up looking like a mosquito fogger for that tank of gas, or whatever the process is?...

I have used ring free but never the "potent" stuff you mention, but have a 30+ year old Merc classic 50 that is starting to get a bit weak, and wondering if that is something I should try.

Also, can you use it in EFI motor like merc 150efi? or just carb motors? thanks for info!

[JohnMickish]

You can use ring free in both a cleaner concentration and a maintenance concentration. In the cleaner concentration you use a separate tank and it works very very well, very, very fast.

[boatfixer]

Box

No because it doesn't go into the gas. You spray it in through the carbs just like you would fogging oil. There will be some smoke when you leave the landing but it cleans out quickly.

What I do is run the engine until its warm. Then run it at high idle (1200 or so). Spray into the carbs. Can says to spray the entire can in, I never have. Then shut the engine off and let it sit for a couple hours. Start it back up and idle high again. Ill often spray a little more in but keep it running long enough to "flush it out". At least until it gets up to temp. Once on the lake, you will have a little smoke but it will clean out quickly. Running under load at higher Rpms will flush the rest out.

I see nothing wrong with using the ring free as a concentrated cleaner. I have a few spare tanks that I might mix up a batch to try that as well. I've never tried method. The engine tuner has always worked for me

[JosMN]

I did this last year. Used seafoam deep creep, seemed to work well. May do it again this year but try the merc product to see if it works any better.

[Black_Bay]

Don't expect the pistons to be nice and sparkly aluminum. There should be black areas. If you have nice clean pistons you are running way too rich.

[Meat-Run]

Black Bay,

My pistons look just like the first one on the left, so does that mean it's OK and may not need a piston "cleaning" or "tune-up"??? Thanks for posting those images that's what I was looking for.

MR

[Black_Bay]

If it looks like the piston on the left then it may, may, be running too rich. Personally I wouldn't mess with it as far as carb settings unless it's running like crud, but using a fuel system cleaner like Yamaha Ring Free or Mercury Quickleen wouldn't hurt. A 2 stroke piston should mostly have a brown top. That is showing a more complete burn of the fuel and oil. You should only have clean aluminum spots near the transfer ports.

This is a pretty good explanation:

I've never read or heard a good explanation... so I can only share what I've learned over the years. If you understand what "piston wash" is, then

it's pretty easy to know what to look for and what to look out for.

The first thing you need to realize is that the top of the piston is not

a uniform temperature. The area in front of the exhaust port that is

exposed to all of the hot gases exiting the cylinder is naturally the

hottest. The area in front of the transfer ports that is cooled by the

fresh air and fuel entering the cylinder is obviously going to be the

coolest. And, the center of the piston will be somewhere in between.

The second important thing is that there is some small range of

temperatures where the piston is hot enough to char the oil that comes in

contact with it, but cool enough not to melt the piston.

Putting those together, you have "piston wash".

When the engine is jetted very rich, most of the piston (except near the

exhaust port) is too cool to char the oil; and you will have large areas

spreading out from the transfer ports that appear to have been "washed"

clean of carbon by the air and fuel entering the cylinder... that is "piston

wash".

If you jet down leaner, the temperature of the whole piston will

increase... and more areas will be hot enough to char the oil. The "washed"

areas will be large circular areas, located just in front of the transfer

ports. At this point, the center of the piston is quite hot; and is

actually charring the oil on the underside of the dome, right in the center.

Jetting down further will cause the whole piston to get still hotter.

Now, nearly the entire piston is hot enough to char the oil... and the

"wash" will be just a small area about the size of a half of a dime, right

in front of each transfer port. The bottom side of the piston will be

charring the oil over a large area by now also. At this point, the area

near the exhaust port is getting almost hot enough to melt. This would be

considered (at least by me) to be jetted correctly... but near the "edge".

If you go leaner yet, the whole piston will be hot enough to char the

oil on top of it and there will be no "washed" areas left. The entire

piston will be covered with carbon, and the aluminum at the edge of the

piston, right in front of the exhaust port will actually be slowly melting

away and smearing onto the rings... more than a few seconds of this and it's

time for new pistons.

That, for whatever it's worth, is my own twisted look at piston wash.

Some things to keep in mind include the fact that the size of the

"washed" area depends somewhat on the upward angle of the transfer port. If

the port is angled flat across the top of the piston, there will be more

cooling and more wash... in spite of the fact that the area in front of the

exhaust port might be just as hot as it would be on a motor with upward

angled transfers that shows much less wash. The upward angled transfers

don't cool as much of the piston top.

Also, the size of the "washed" area has to be somewhat proportional to

the size of the piston. A "half a dime" sized wash area on a 600 triple

(very small piston) means the piston is a lot cooler than a "half a dime"

sized wash area on an 800 twin (with coffee cans for pistons)! What you're

really interested in is how much of the piston isn't clean, because that

tells you how much of the piston is hot enough to char the oil... and you

know the exhaust area is hotter yet.

All this really means is that you can't just say, "Every motor should

have a half-dime sized wash area." You have to correlate the size of the

wash area to other indicators and engine specs... and use it as just one of

your tools for jetting."