[aladad]

Hello, new to the site. I work in a small engine repair shop. I have been coming across a lot of excessive buildup of carbon on the valves and piston. I believe it is caused by ethanol, but am not sure. This has been found on all makes of engines. Warranty does not want to cover this, because they say fuel related issue. Any suggestions?

 

[Rentahusband]

I never have had an issue with my personal equipment or the ones I have repaired. I usually burn premium fuel and add a stabilizer when I fill the 5gal can. I wonder if it also depends on where the fuel is purchased. A private station vs a chain station.

 

[aladad]

All of the customers have admitted to using ethonal fuel. The problem is that the manufacters say the units will run on it. I am seeing that it is causing some serious problems in small engines. I always reccomend to customers to run premium fuel. The carbon is building up the worst on the exhaust side, not allowing the valve to close. I have three units in the shop now, all with the same issue, all different makes of engines. This is what is making me believe that it is a fuel issue. Or is there something I'm missing.

 

[chuck_thehammer]

I would take a closer look at the exhaust valve GUIDE and SEAL.
todays oil is thiner and evaporate easer than years ago.

also ask if owners are using 5w type of oils.

 

[aladad]

Will do Chuck Thanks. Also was talking to a friend of mine. He said he was having a problem with carbon on his harley. He went to a colder plug and seems to have solved the problem. Wonder if this would work on lawnmowers.