My Dad had a boat with a Detroit 6-71. The boat had two fuel tanks and a
rack of batteries on the starboard side, consequently, the boat had a list
if the fuel tanks had equal amounts of fuel. To keep things trimmed up, he
would run off the starboard tank until the boat listed to port and then run
off the port tank. (Bet you're wondering what this has to do with smoky
engines)

One time when switching from one tank to the other, we closed one tank's
supply and return valves, and only opened the supply valve on the other
tank. A cloud of black smoke followed us because the engine could not
return fuel to either tank. Assuming 8-92s have a return line, could it be
that yours is restricted?

Snafu

"Capt. Dan" wrote in message
om...
have purchased a 46 ft. Viking Sportfish.. 1984 Detroit 892 Turbo
Hull No. ID

Both engines have been completely overhauled last spring and have
apprx. 450 hours on them.. Boat performs well while underload at 1950
rpm it cruises at 20-21 knotts. At 2350 rpm boat can run 24-25
knotts. No load engines run rpm up to 2650

After several months and various mechanics in Freeport,Texas,
LaMarque,Texas, Galveston,Texas I still have a problem with engine
smoking diesel. Enjectors have been calibrated and adjusted, but when
boat is loaded with 900 gallons diesel, 80 gallons of water, and 8
fisherman with supplies, we find the engines smoke (both) while
underway.. Unless the boat is on top of the water and cruising at
least 1800 rpm (17knotts) we have very bad diesel smoke problem.
Dreadfull smoking at low speeds, but when boat is running high rpm and
cruise at 19-21 knotts we have less smoking, but still too much as the
smoke covers the transom and back of boat within 8 hours. We are not
burning any Oil while running. If any, less than 2 quarts per 24 hours
of cruising.

I clean the air filters (4) before every trip out, but we still find
black diesel smoke all over the boat.
I am at an impasse as what the problem is. Everyone seems to have
ideas and suggestions, but nothing is resolved. I have owned the boat
for over a year and spent time and money on upgrades, cosmetics,
electronics, and engine rebuild, new wheels and tuneup of wheels per
Hood Marine Propeller Shop in Houston,Texas..

I recently looked at pictures of 1982-83 Viking 46 and picture showed
that there were air scoops and ventilation to engine room on outside
of hull.. 1984-1985 model (like mine) have air ventilation in
cockpit.. When the 47 ft. Viking came out the next year, the
ventilation was back on the outside of cockpit and on the side Hull
as years previous.

Is this a cause of the black smoke on my 46 Viking? Am I not getting
enough air into the engine room. Everything is standard equipment, but
this could be a problem.. Can you lend any assistance or advise

I run a pair of Detroit 6V-53s. Get a fair amount of smoke on startup, none
while running. 6v-53s are 2 cycle with blowers on top.

Thanks to all for your advice. I have some things to check on my side
and will back to you after the weekend. -Dan

dan.sherwin relates:

-have purchased a 46 ft. Viking Sportfish.. 1984 Detroit 892 Turbo Hull No.
ID

Both engines have been completely overhauled last spring and have apprx. 450
hours on them.. Boat performs well while underload at 1950 rpm it cruises at
20-21 knotts. At 2350 rpm boat can run 24-25 knotts. No load engines run
rpm up to 2650

After several months and various mechanics in Freeport,Texas,LaMarque,Texas,
Galveston,Texas I still have a problem with engine smoking diesel. Enjectors
have been calibrated and adjusted, but when boat is loaded with 900 gallons
diesel, 80 gallons of water, and 8 fisherman with supplies, we find the engines
smoke (both) while underway.. -

Bilge- Do you dose your tanks with biocide? The little buggies will do a pretty
nice job of goobering up your fuel system...your tanks are also 20 years old,
right?

Did any of the mechanics you brought the craft to "pop-test" the injectors? Or
did they just replace 'em without testing 'em?

Do you have a fuel oil purifier in your system?

Black smoke without excessive LO consumption has to be the result of
incomplete combustion.

Too much fuel, insufficient atomization, injector afterdribble, insufficient
compression, or insufficient air.

We have a 7 cylinder Sulzer RND two stroke, twin turbo slow speed, at about
14,000 bhp downstairs, unfortunately, Maersk built these ships with salt water
cooling,(never meant them to be in service past 20 years).

G'luck;


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