I have a 06 Mercury Verado and just changed my plugs. They had a fair amount of carbon on them, which leads me to believe that a shock treatment would be good for the engine. Is Seafoam as good a product as any other for decarbonizing pistons?
Also there is heavy carbon buildup on the inside of the prop. What can I use to remove this or does it matter?
Use Mercury Quickleen or Yamaha Ringfree instead. I would not overly shock the system; just start using this stuff on a regular basis and it will clean up whatever is there. Don’t worry about the prop.
How are you running the engine most of the time? It seems a bit odd that you have soot on the exhaust outlet with a 4-stroke.
Iain Pelto
Edgewater 185CC “Jumpin’ Bean II”
Native Manta Ray 14