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I have twin 230hp Yanmars. Does anyone know what would cause the exhaust water to be dirty brown? This new condition occurs while under load. - RH

Overload of the engines, caused by dirty botom, fouled props, or dirty air filters. I fished on the Geaux Deep a lot with Garry, and she'd spout some normal black smoke coming up on plane, but nothing after that. Brown exhaust is a sign of too much fuel going in for the rpm's, and the rpm's are being dragged down by one of the above.

I'd say haul her and clean the bottom, shafts, struts, props & rudders.

UV

UV,

Thanks for your response.

I had a bottom job (pressure wash, sand and painted) both shafts and couplers pulled and engine alignments done along with props cleaned. Also replaced both cutlass bearings. Both rudders repacked. All of this work was completed the last of May. Boat runs smooth as silk. The dirty exhaust problem just started within the last two weeks. I am not putting out black smoke on plane just when the turbos kick in. My deckhand reported the brown water to me Monday while on a charter. Myself, deckhand, 6-full grown passengers, gear, ice and full limit of double digit Red Snapper and full fuel, she was loaded. I have had equal loads before but I have not noticed the brown water before. Could dirty turbos cause this problem? I am going to clean them this week, they are over due. - RH

Randle - that's a mighty big load you described. Turbos probably need a wash, but let's think in aviation terms here. Density altitude. Hot, humid air is a lot thinner than cool, dry air. In the summertime around here the heat and humidity can raise the apparent altitude by a couple of thousand feet vs. a cool dry day. In addition, the very warm sea water temps will reduce the efficiency of the aftercooler a good bit. I've noticed the same thing on AJ this time of year. Hot, damp, big loads equal some smoke at cruise. Normal.

UV

Randle,
Sure could use the Red Snapper bite down these parts as we have more RedTide again close to shore. Got to run with the live well not on suction untill you clear it. Pain in the but. Now your brown smoke. Try a run with a light load an use Tony Athens method per UV for cleaning your turbos . Simple and effecient way. Process of elimination. Also don't think you have any other propblem than discussed but for piece of mind you can have you oil checked for $20 an engine.
Always something. After I added the bertram deck, nida core boxes and walkway etc, heavy insulation , frig and things I'm using more fuel. From 1.2 KMPG to 1.1 KMPG. I'm on a lift so bottom not an issue. Time to check props.Let us know what you find. Oh yea send some of that good water our way. Dave K

What color is the water you are running in? Are you running in blue water or Mississippi mud colored water?
Engine overload produces a black color to the water from soot of low O2 combustion. Besides as you indicated you only get the short puff of black as the turbos spin up on plane.
Rust and oil can produce brown water.
bruce

Bravo, Bruce, you correctly read the problem as brown water, not smoke. Puzzling. We get some brown water in the creek here, but it doesn't come out the exhausts with noticeable color. Not that I sit back there and watch it much. People curse me, also, but until now, I didn't realize what the problem was!