Robin-Subaru lots of carbon in cylinder

[GearNut]

An even film of carbon is normal. If it is all chunky and thick, like 1/6" or 1 mm thick in spots, then you have problems.

 

[Old Bob]

Thanks for all the advice... MM i love the poem.

Silvaire I have the right amount of oil and the air cleaners are dry so I think ill let it be. The engine is running great I was just worried to much carbon would cause a problem.

Under normal conditions it builds to a certain point and doesn't build any more.The mere presence of carbon deposits does not mean there is a problem. Most people would load their pants if they saw the inside of their car engine after 50,000 miles.

 

[BigDaddyT]

I was told by an old timer to run the rpms up and drop a teaspoon of water in the carb and it will decarbon the engine somewhat.

 

[Happy Valley]

Yes, they do carbon the piston crown. I've conversed with Robin/Subaru factory service techs on this and told not to sweat it, about what I expected. I believe in part it has to do with the EPA compliancy and recycling gases back through the cyclinder.

I also believe Seafoam, in moderation, is the EHO35's friend.

 

[GearNut]

Any gasoline powered ICE engine develops carbon build up. Gas is, afterall, a carbon based fuel. Petroleum, AKA dead dinosaurs and plant matter.

 

[arceeguy]

I agree with the others, not a big deal unless it is causing problems with pre-ignition.

I would also refrain from any fuel additives. My thinking is that if the solvent is powerful enough to clean carbon off of the piston, what is the solvent doing to the lubrication film on the cylinder walls?

 

[Happy Valley]

To mitigate carbonizing I use Seafoam but strictly as an upper cylinder treatment IE: a teaspoon misted into the intake of the warmed engine with near WOT once or perhaps a couple of times a year depending on engine hours.