Black Exhaust Water - Soot ?

[sabray]

Originally Posted by Capn Morgan

Hi Sandy

I do no know enough to talk about the external filter sizes. Mine are 2 micron because I want them to stop anything before it gets to the engine mounted filter. The Racor ones are much cheaper and easier to replace than the Yanmar ones.

As for the soot, I agree with the post above in that I think it is old carbon deposits in your exhaust system that will either clear up in time with use or you are going to open it and do it yourself.

Either way, good to read your follow up, keep sharing the fun!

Cheers

M

Me too first filter is a big honking 1000 series racor with 2 micron filter. I keep a few spares. Never have seen them gunned up though.

[perchance]

With regards to prop pitch think of it in terms of a manual transmission. Over pitched is equivalent to driving up hill in high gear. You will be lugging the engine and eventually kill it. Under pitched = low gear you will be over revving and will eventually kill the engine.

[Tide Roller]

So I realize that the last post for this thread was a few years ago but I am having a similar issue with my universal m25xp. Can not get above 2000RPM in gear and above 1500RPM gives the black soot with smoke. Cleaned the air filter, exhaust riser was rebuilt and I cleaned the mixing areas where exhaust meets water. There has been 75 gal of fuel run through at high RPM with not much else than a dirty transom. The filters have been changed a couple times and no help.

Manual says low compression, overload or propeller
I am thinking about compression testing the engine, but this thread has a lot of info about over pitching. The prop for all I know is original and hasn't given any issues before but I have about 1yr experience with this boat. (83 Catalina 36).

Would excessive prop-walk in reverse indicate it is over pitched? It's almost as if I can't back up straight at all. Even when the rudder is hard over to the opposite direction. Over pitched?

Sandy or anyone, if you can give me a solution that worked I would greatly appreciate it.

[atoll]

have you cleaned the prop?
is the hull dirty?
a few barnacles can make a Big difference