Diesel engine smokes after many hours of very light load
 

I have a big old Deutz engine installed in a 50 foot boat. Big old
Deutz 6FL714.

Now i had to travel for around 200 hours in the french canals - they
have a speed limit on the canals - as a result I always ended up
running the engine at 900 rpm (minimum recommended is 800 rpm). Even
at 900 rpm the boat was doing 9 km/h instead of the permitted 6 km/h...
I know I'm not supposed to run diesel engines almost at idle but I had
no other choice.

Note: the engine is air cooled so it can not be water.

Anyway: what happens now is the following.

Right cylinder bank: always no smoke from the exaust.

Left cylinder bank: at low rpm, always some white smoke (not much).
When the engine is run hot (1800 rpm), less white smoke. If i return to
low rpm, no smoke at all, then with the time (and engine cooling down)
the withish smoke returns.

At 1800 nice pieces of black soot where flying out of both the exausts
... and some black smoke too.

My idea is that running the engine at very light load "coked" the
engine. Is adding some "magic" additive in the diesel a good idea ? Or
better leave it as it is ?

This before i fork out money for compression tests and the like, the
engine is normally run at 1100 rpm or so and is almost never operated
to full rpms.

Cheers
Matteo

wrote in message
oups.com...
I have a big old Deutz engine installed in a 50 foot boat. Big
old
Deutz 6FL714.

Now i had to travel for around 200 hours in the french
canals - they
have a speed limit on the canals - as a result I always ended
up
running the engine at 900 rpm (minimum recommended is 800
rpm). Even
at 900 rpm the boat was doing 9 km/h instead of the permitted
6 km/h...
I know I'm not supposed to run diesel engines almost at idle
but I had
no other choice.

Note: the engine is air cooled so it can not be water.

Anyway: what happens now is the following.

Right cylinder bank: always no smoke from the exaust.

Left cylinder bank: at low rpm, always some white smoke (not
much).
When the engine is run hot (1800 rpm), less white smoke. If i
return to
low rpm, no smoke at all, then with the time (and engine
cooling down)
the withish smoke returns.

At 1800 nice pieces of black soot where flying out of both the
exausts
.. and some black smoke too.

My idea is that running the engine at very light load "coked"
the
engine. Is adding some "magic" additive in the diesel a good
idea ? Or
better leave it as it is ?

This before i fork out money for compression tests and the
like, the
engine is normally run at 1100 rpm or so and is almost never
operated
to full rpms.

Matteo,

I would re-pitch the prop to a lesser pitch, resulting in a
higher RPM to make the restricted canal cruising speed. The
higher RPM, would make the engine run a bit cleaner in regard to
the coking problem.

Leanne

Sounds like a bad case of Remoras.

So Larry, you were on a minesweep back when there were some in Charleston?


Larry W4CSC wrote:
oil is as bad or worse than coolant. Diesel engines can RUN AWAY burning
lube oil from the sump....and explode! Really not good. You have to see
it to believe it! Standing in the engine room of a wooden minesweeper
watching a 12-cylinder Packard diesel running away is even more
exciting....it came in through the supercharger leaking.

DSK wrote in
:

So Larry, you were on a minesweep back when there were some in
Charleston?


1966-1971...USS Everglades - MCSU...wouldn't trade it for anything. Being
a prisoner was never happier....

"Shore Duty"....that's what they said it was when I was on the MSO headed
for the Med....At first the Minelant little shipyard was called "Minecraft
Support Unit, Atlantic" but that was too easy so they changed it to Mine
Force Support Group, Charleston. Later, they changed the name to SIMA, as
they did more than minesweepers..Shore Intermediate Maintenance Activity.

Got to ride the old MSOs and MSCs while fixing their radio/radar gear.
Minesweepers had a very small electronics gang, so they took the senior ETs
from MCSU when needed. Great fun in a wooden boat, 7' draft, in the N
Atlantic in the Winter. How far can YOUR boat roll?....(c;.....Lash some
big heavy rubber diesel fuel bladders to the top of the main deck and it
rolls even further!...

Navy had a torpedo-sized towed sonar device that had active sweeping, side-
looking, sonar on it to scan for bottom mines. There was a "shack"
strapped to the stern where the operator's console was located because
there was no such room inside an MSO to spare. Also on the stern was a 2-
cylinder, V-twin diesel generator to provide "stable" power to this
technological nightmare. Whoever signed off on the system worked for the
Soviets. God it was awful! The genset had electronic throttle controls.
If these controls failed, instead of the injection shutting down, IT WENT
TO FULL THROTTLE...WIDE OPEN! There were many failures. One of the MSO
captains was so concerned for his ship and crew safety (wood burns, you
know) he ordered the uncontrollable genset pushed overboard off his stern
as it was running so fast there was the possibility of it exploding in
flames. I heard it suck up its first full breath of seawater as it sank at
full power. The towed bodies had sonar that looked at 45 degrees towards
the bottom out both sides and the helical-scanning fax-type printer gave
you two very nice "pictures" from nearly under the towed body out quite a
ways. It was kept 15' off the bottom by another little sonar that looked
down like your depth sounder does. UNFORTUNATELY, none of the idiots that
designed it had a sonar looking and displaying FORWARD of the
thing....so....as you've already imagined...it used to RUN INTO EVERYTHING
OVER 15' TALL! Duhhh....(c; Made of fiberglass, lots of them came in all
crumpled back to the shop. Can you say "boondoggle" without cursing? The
towing minesweeper had an old navy sonar on it that couldn't display a
sunken sailboat...or big pipe sticking up....or an uncharted hulk...so the
thing simply ran into it....stupid, eh? We didn't design it, we just
patched it up, if it weren't destroyed.

They also had this same boondoggle on a little barge they could hang down
under a helicopter, which was supposed to tow it over the minefield without
risking an MSO, EASILY destroyed by acoustic mines that didn't give a ****
if it wasn't magnetic. Only trouble with that thing was it kept COLLAPSING
when the helo tried to pick it up with all that weight on it! More
boondoggle. I think they scrapped it and shredded all the paperwork...(c;

As Vietnam was winding down, one of our Chief's got dumped before he could
retire after 18 years of loyal service, so I took the hint and left from
there when my 2nd hitch was up. No longer needing us, any excuse to rid
the government of retirees would do.

I think they were trying to get even from my "Sea Duty", 3.5 years aboard
USS Everglades (AD-24), CRUDESFLOT 6's destroyer tender and admiral's
office mostly strapped to Pier Papa on Charleston Navy Base. Destroyermen
called us, lovingly, "Building AD24"....even though I did two Med cruises,
a couple of Caribbean cruises, GITMO RefTra and several Mayport excursions
to do work USS Yellowstone couldn't do themselves. Everglades was a
steamer, for an AD. May she rest in peace.

Well, that's my story....what's yours?

In article , says...
Great fun in a wooden boat, 7' draft, in the N
Atlantic in the Winter.



I was a Bosuns mate on a gator freighter and, while crossing the
Atlantic to relive the Med. squadron in the fall/winter of 66 we had
several mine sweepers attached to the squadron.

About half way across we ran through a storm big enough to be taking
green water over the bow.

As I remember it, for most of the time, we couldn't see the sweepers
because they were spending most of their time playing submarine.

We had to leave them in the care of an LST while the rest of the
squadron ran ahead, we couldn't go slow enough and maintain steerage way
to stay with them.

A week after we got into Naples the LST showed up without the sweepers.
They showed up a couple of days later. As I understand it the Captain of
the LST was in deep doo doo for leaving the sweepers.

--
Mike G.
Heirloom Woods

www.heirloom-woods.net

DSK wrote:
So Larry, you were on a minesweep back when there were some in Charleston?


Larry W4CSC wrote:

oil is as bad or worse than coolant. Diesel engines can RUN AWAY
burning lube oil from the sump....and explode! Really not good. You
have to see it to believe it! Standing in the engine room of a wooden
minesweeper watching a 12-cylinder Packard diesel running away is even
more exciting....it came in through the supercharger leaking.


I am still trying to figure out the relevance of these comments to the
original question. Deutz engines are 2 stroke diesels. NO SUMP.

Larry W4CSC wrote:


Well, that's my story....what's yours?


Gin & Tonic please - with ice and lemon.