In article ,
Capt. Dan wrote:
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
Sure.
First, I HIGHLY DOUBT that you have an engine room air problem. Those
problems only show up at higher RPMs, and YOUR problem is showing up at ALL
RPMs. However, they're simple to check.
First, we need some more information.
1. What is the full-load, WOT RPM. Your no-load RPM is TOO HIGH - it
should be 2500 RPM. You need to fix this - being 50 rpm over is ok,
but 150 RPM over is NOT. Also, you MUST use a phototach for this -
bridge tachs are NOT acceptable, as they are almost NEVER right.
2. The fact that the no-load RPM is wrong means the governor is out
of adjustment and the rack may be as well. Have whoever did the
tuneup last time come back and do it correctly this time.
Once you know that stuff is correct, in order of complexity, begin he
1. While underwater, PULL THE ENGINE ROOM HATCH. If the smoke
disappears, you have too much restriction on the air intake into the
engine room. You will NOT like what it takes to fix this, but if
that's the problem, there's your issue..
2. Attach pressure gauges to BOTH the airhorn and airbox ports.
Go for a run. Your AIRBOX pressure must EQUAL OR EXCEED the arihorn
pressure. Also, report boost levels (at both airhorn and airbox)
at 1800, 1900, 2000, 2100, 2200 and WOT (which should be at least
2300) RPM.
3. Any starting anomalies? Describe the engine's behavior on a cold
start at a given (you choose) ambient temperature where it has not
been run for at least 48 hours (that is, the blocks are room
temperature cold) WITH NO BLOCK HEATER ASSIST.
Report back and we can go from there.
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