View Full Version : 2000 Challenger 2000 240HP Merc Smoking

06-01-10, 08:45 AM
I bought a boat last winter, so this is the first weekend I got it out. Ichanged the plugs and it fired right up but it smokes. When I am idling or going through no wake zones it is smoking pretty bad. As soon as I give it some gas it clears right up and flies?

Is this just crap oil that was in it? It is the 240HP Mercury. Any suggestions?

Brad Law
07-01-11, 11:21 AM
I have the exact same problem what is the answer

07-02-11, 02:31 AM
I suggest doing two things. Switch to a full synthetic oil. I use this one: http://www.amsoil.com/storefront/hpi.aspx

Also I recently discovered something else that helped. I cleaned the cylinders and pistons with this:


Remove the spark plugs and spay this in through the spark plug holes. Rotate the flywheel to get the stuff spread around and spray some more in. Let it stay in there for a few days or longer or even a week. Lightly screw the spark plugs back in while waiting so it doesn't evaporate. After waiting a few days or more remove the spark plugs and rotate the flywheel to get most of the stuff out. It will disolve all the carbon into a reddish liquid. Install the spark plugs back in and run the boat on hose water.
A huge plume of smoke will come out of the boat but it will do a great job of removing the carbon. Some people recommend Seafoam but this stuff is much better.

I discovered that the boat doesn't smoke as much after doing this.

07-02-11, 06:40 PM
For what i know it looks like the Reid valves!! Nothing you can do about it right now unless you want to start a big Job!!!