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Seafoam ...WOW

Posted by optsyeagle (My Page) on
Wed, Apr 30, 14 at 16:11

I thought I would post a picture of my lawn tractors piston after my seafoam treatment.

I changed the head gasket on this mower, a B&S 16.5Hp 31C707 lawn tractor, last week. This mower also has a small leak on the carbs inlet needle which I have band aid fixed with a manual fuel shut off valve. The week before I changed the gasket I thought I would give this mower a good dose of seafoam in hopes of dislodging any gunk that might be in my carb.

I first put in about 500mL of gas (about a pint) and ran the mower for about 5 minutes to warm it up. I then added 60mL of seafoam to the gas. I ran it this way for about 10 minutes and then shut it down for about an hour. I then ran it for another 5 to 10 minutes and shut it down for another hour. I then ran it for 5 minutes and then added about 1 gallon of gas to dilute the seafoam. I then road it around my lot for about another 5 minutes or so and that was it.

I was completely amazed at how clean that piston was. This is after 10 years of an hours mowing every week all summer.

Anyway, maybe they all look like that but I thought it would be a lot more carboned up. That is exactly what it looked like once I removed the cylinder head. At around 2:30 o'clock you can see where the breach in my gasket was.

This post was edited by optsyeagle on Wed, Apr 30, 14 at 16:23


Follow-Up Postings:

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RE: Seafoam ...WOW

Very good stuff, I use it myself.


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RE: Seafoam ...WOW

I promise you, they (pistons) do not all look like that.
They often look like this (pic below), or much worse.
The photo was not of something I worked on, it was a photo sent to me from somewhere. But I am pretty certain Seafoam was not part of its diet.

This post was edited by mownie on Thu, May 1, 14 at 10:21


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RE: Seafoam ...WOW

That was about what I was expecting. That one also looks like it had a lot worse of a head gasket breach then mine did.


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RE: Seafoam ...WOW

Curious if you got a lot of smoke when you ran the motor after it had loosened everything up. I have used it in a number of cars, sucked through a vacuum line not diluted into the gas tank. It can generate a huge amount of dark clouds - much like a big fogger. I started doing it so that the final drive of a few miles would be after dark because it was such a big deal. End results have been uniformly great as far as cleaning up a lot of the innards and making motor run better even when it seemed to be OK before. Hadn't thought of using it on the tractor, but great idea.


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RE: Seafoam ...WOW

There was a little more smoke then usual. Not overly dark but more visible then it was without the seafoam.

I have added a little to the gas (1.5% v/v) at the beginning and end of each season, for the last couple years and I sprayed a liberal amount through the carb at the end of last season, so perhaps that took away a lot of the crud as well.

The reason for that was because my spark plugs would end their season, pretty crudded up. Probably from the burning of oil. I figured if this crud was getting on my spark plug it would also get on my piston and rings so I did what I could to clean it up.

I put the high concentration of seafoam in the gas this time because I am hoping to clean the carb a little as well. No idea if it worked but that is the cleanest 10 year old piston I have ever seen.


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RE: Seafoam ...WOW

Carbon build up is good on top of the slug. It builds compression ratio = more power!LOL!


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RE: Seafoam ...WOW

***"Carbon build up is good on top of the slug. It builds compression ratio = more power!LOL!"***
LOL is correct on that.
Carbon build up actually decreases overall power output despite the increased compression load.
The net effect of carbon build up on top of the piston and inside the combustion chamber is to decrease the volume of space available to pack air/fuel in during the intake stroke. less combustible material in means less power output.
Or, to put it another way, your 31 cubic inch displacement engine is now displacing only 28 cubic inches. Carbon build up equals smaller engine.
Carbon build up on the intake valve (manifold side of valve) means the induction draft will be impeded by the partial obstruction, resulting in a lesser charge of air/fuel mix getting into the combustion chamber. Carbon on intake valve surfaces equals smaller valve effective size.


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