Black stains from exhaust. How to clean / prevent?

[stuee]

Hi all.
Again i come to ask the advise from the great people of this board

I have a 86' 235 johnson outboard. I used to run the fuel 40/1 as it was a new engine to me and i know it had been sat around for years. After everything was realized to be ok i started running 50/1 recommended.
My problem is that it always makes the leg front black and dirty from the exhaust.

Can anyone explain why or a way to stop it (some type of paint) i know the previous owner went over the leg with a cheap can of white spray paint, could this be the problem?

i can take photos if requested..

thanks

 

[emdsapmgr]

It's likely not an 86. The last year for the 235 was 1985. A picture would be helpful. Normally, the leg doesn't accumulate exhaust soot. Just where is the soot-that may reveal the reason. Is it coming out of the exhaust relief holes at the top of the midsection, or is it running down the top of the midsection from the base of the powerhead? If it's the latter, could be the exhaust o-ring has failed-permitting exhaust to seep out from under the powerhead and down the exhaust adapter onto the leg. If that's the case, you'd have to pull the powerhead and install a new base gasket (323214)and exhaust 0-ring (336429.)

 

[Bosunsmate]

EMD- mines got a stain out of the relief holes- what could cause that? thanks

 

[stuee]

Emd, thanks for the reply. i will take a photo this weekend when i go the shed. It is from the relief valve holes.

 

[emdsapmgr]

It's an unusual problem. Hard to say where to start, but some suggestions. If the engine is running cold, the carburetion will be rich. Also, possible the engine is sitting low on the transom when at rest. This can restrict the effectiveness of the relief ports and could smoke more..