View Full Version : What's the Procedure For De-Carbing A Four-Cycle I/O Engine

09-20-2010, 05:11 PM
I have used a de-carbing method on two of my 2-cycle outboards using Seafoam. The motors ran better after doing this procedure a couple of times. It is suppose to loosen up the carbon in the combustion chamber and piston rings.

I used approx. 8 oz. of seafoam in one gallon of fuel. Ran the engine for 10-15 minutes and shut it off and let it set for 30 minutes or so. Then started it up and ran some more. Then switched back to the normal fuel tank and ran the boat wide open for a while.

Can this same procedure be used on a 4-cycle I/O, or is it different?

James Cole
09-22-2010, 01:01 PM
There are some instructional videos on YouTube from other SeaFoam users. (and some not so instructional but fun to watch) http://www.youtube.com/results?search_query=seafoam+engine+cleaner&aq=1

SeaFoam also has good directions on their site:

I think everyone with anyone with any kind of gasoline engine ought to have some of this stuff. It worked wonders on my motorcycle's fuel system.

09-22-2010, 08:36 PM
Thank you for the links. I'll look it over....

09-23-2010, 11:48 PM
I use the mercury product "Power Tune" - directions on the can are self explanatory. It will do two and four cycles just fine. only 'trick' is to follow ALL the directions.

10-02-2010, 07:55 AM
Can this same procedure be used on a 4-cycle I/O, or is it different?

Ayuh,... You Could do that, but I don't know why you'd want too...
If the motor is mechanically sound, there's absolutely No reason for this...

On a side note,... If I've got a running motor I'm going to tear down,... I'll de-carb it before I start...
Warm the motor,... Kick it up to 1500rpms,... Then slowly pour a pint of Water down the carb throat....
The combustion chambers will be Spotless when you get it torn apart....