Black Soot on Stern after long idle

[TOGA]

After spending a good bit of time idling through marinas looking at boats for sale, I noticed black marks under the swim platform around the exhaust. We normally don't idle around long periods of time and I have never had the build-up of black marks before.

concentration is on the port side engine. I have noticed that the engine is requiring some oil on occasion and there is a small leak toward the stern side of the motor, but after reading threads regarding some leakage, I don't think I am losing an amount to cause alarm.

We normally run the boat 2 days a weekend three weekends a month. We put 100 or so hours on it a year. Probably has 500 hours on the engines. Can't be sure cause hour meter quit working one year and I haven't hooked up diagnostic software to check, but i did replace hour meter and run it past the last know reading.

Anyone have ideas as what caused the build up? Do I have an issue I need to be looking into?

Boat runs fine with no issues.

Any guidance appreciated.

 

[justason]

I ran a thread like this under the 212x section . My 212x soots up all the time, specially under load like surfing or hammering a submove or jackass turn. it is moreso on the port side, and I often have to add a quart of oil. nothing definitive ever came from it.
here's the link

https://jetboaters.net/threads/soot-exhaust-build-up-on-my-212x.2475/

p.s.: same here, boat runs fine

 

[TOGA]

Thanks for quick insight. Haven't changed plugs in a while since it was performing fine. Looks like two easy things that won't hurt are plugs and ring free.

 

[justason]

After I ran that thread I got the ring free and the also did seafoam. no difference

 

[KXCam22]

My 230 soots up a bit at times. Cam.

 

[jcyamaharider]

Same here. I get soot, especially after surfing. Boat still runs like new.

 

[jetboater4life]

Mine will have some soot to. Once a year I will grab a bottle of isopropyl and clean up the rear of my boat.