Black Stains around exhaust outlet

[dcharna]

I just purchased a new to me 2003 340 sundancer. I have put around 8 hours on the boat which only had 130 to start the season. I just noticed today some light black staining around the above water exhaust outlet on the port side (can't see the starboard side). Is this normal for 8.1 gas engines? When I surveyed the boat, the compression was great around 160 and only 5 pounds off on any one cylinder. Oil samples were also normal. What do you all think.

Dan

 

[sbw1]

I would not be too concerned about a little stain around a white exhaust port. My 454's did this from day one with a new SR and for ten years. Those engines were perfect. The current boat does not do this, but it has under water exhaust with above water exhaust for pressure relief. It also has stainless steel rings around the exhausts that could be sooted a bit, but I do not see anything when I pull the boat.

 

[mainstream]

With only 8 hours was the boat laid up over the winter out of the water if so it could be the carbon deposits left after all the moister dried I get it for the first couple hours every year after seasonal lay up.

 

[dcharna]

Thanks.

I was told by a Merc tech to try Sea Foam. Anyone ever use it. It has rave reviews on all the websites.

 

[Jimmy Buoy]

Ive got 8.1's now with 550hrs (purchased it with 200hrs) and it has ALWAYS had black carbon deposits around the thru hull exhaust ports on both sides. It comes off easily enough with just about any boat cleaner. Compression is good on both engines and they run great. I'd say it's normal for these engines. They seem to run a little rich...

 

[sbw1]

I think 8.1s run just right. It's all controlled by computers and mine don't smoke one bit. It is probably just carbon. Both of my cars have black soot outside of the exhausts. One has two thousand miles on it and the other fifteen thousand. It's the nature of gasoline engines to lay down a little soot.