"Roger Long" wrote in
:

I'm sure he meant "un(completely)burned" fuel. It's the ash of partly
burned fuel when the engine is too cold to promote full combustion
that causes the problems. It doesn't even have to clog the injector
enough to stop the flow of fuel. A little clot of carbon on a nozzle
can break the spray pattern and turn it partially into a stream which
has less surface area for its volume and thus burns less completely
leading to further carbon build up.



Sorry. I've been running diesels for lots of years and NEVER had an
injector clog because of the fuel. Injectors clog because of crap IN the
fuel, things high pressure injection pumps can't force past the orifice.
I've never seen any carbon on the outside of an injector clog it against
the hundreds of PSI of injection pump. I'm sorry. A little clot of
carbon could, I suppose break the spray pattern. I'll buy that. But,
it's never happened to any vehicle or boat or genset diesel I've had
contact with....and that's a lot of diesels.

Two things would cause the carbon....too much injection on too little
air...or...too much LOAD, which is normally what's up with that black
cloud of smoke at full throttle. In a boat, too much prop. There's no
reason for a diesel to make lamp black, especially not now with
controlled injection.

What diesel do you know of with this carbon problem, anyway? Carbon in
the pipes is normal, black, gooey snot saturated with unburned fuel a
diesel always produces. Diesels make soot because they run out of air,
usually about the time the exhaust port comes uncovered in a big 2-stroke
beast, or the exhaust valve opens opens, if it has one. But, that
doesn't "clog the injectors".

http://people.bath.ac.uk/ccsshb/12cyl/
I just wanna see and feel it run....(c;

Well, your direct experience may well be more valid than my hearsay. I've
spent 30 plus years around people who run big diesels for a living and I'm
just inferring from the gripes I've heard.

It may also be that fisherman, tug boat operators, and the like run their
engines a lot harder and longer. I certainly see more black smoke coming
out of the exhausts of commercial boats than yachts. The ones that stick in
my memory may also simply have been wrong about what was ailing their
engines.

I've never had the opportunity to see the inside of an abused diesel
cylinder at overhaul but the impressive build up's I've seen in aircraft
engines make it pretty easy to believe that carbon could effect the spray
pattern out of an injector without reducing it. You would think that
nothing could survive in the environment of an internal combustion engine
cylinder but physics are strange. If there is dust on the wings of your
airplane before you take off, a lot of it will still be there when you land.

--
Roger Long

On Fri, 5 Jan 2007 14:03:28 -0500, "Roger Long"
wrote:

I've never had the opportunity to see the inside of an abused diesel
cylinder at overhaul

I have a few pictures if you're interested. Basically they show scuff
marks on the cylinder liners and pistons from where the pistons
started to seize up. Probably the most expensive pictures I own. :-)

I feel your pain. Somewhere, I have a picture of the cam lobe missing .005
inches of its top that cost me and my airplane co-owners $25,000.

--
Roger Long

"Roger Long" wrote in news:459ea606$0$18859
:

I certainly see more black smoke coming
out of the exhausts of commercial boats than yachts.

Commercial boats get paid for WORKING, so maintenance goes undone until you
can't go WORKING any more. (An example is Charleston shrimp boats go
uncaulked until they're leaking so bad the pumps can't keep the water below
the intakes to go shrimping, their prime reason for being.)

Yachts get maintenance, most well before they actually need maintenance
because the owner has money and nothing to do with it. Ain't it grand?

Also, a fisherman headed out to be number one isn't interested in "sweet
spot cruising" to the fishing...(c;

Reasons for all the black soot shooting out the dry stacks welded up by
Uncle Henri are fairly obvious...(c;

"Roger Long" wrote in news:459ea606$0$18859
:

I've never had the opportunity to see the inside of an abused diesel
cylinder at overhaul

Has nothing to do with boats, but my 1973 Mercedes naturally-aspirated
2.2L 4-stroke 4-cylinder that spent the first 23 years of its life
driving across Charleston City traffic, owned by a retired Navy captain
and his wife, is probably a pretty good example of an abused diesel. 23
years is the point at which I did a 4-hole overhaul on it, somewhere in
the 330,000 mile area, but we're not sure how many times it went around
its 99999 mile odometer before I got it. The Captain couldn't honestly
remember when I bought it from him. It sat idling in the awful city
traffic most of its life before I got it....and since I overhauled it.

One cylinder was lower in compression than the others, so my mechanic,
Stephan Reinhardt, a German who worked at the main engine factory before
coming to the US to start his own Mercedes shop, Star Motor Service,
decided to pull it apart. One of the compression rings was cracked and
he made me a great price on doing a full overhaul, restoring the little
diesel to new condition. I was amazed how little carbon and deposits
were in the cylinders and in the pre-combustion chambers in the head
where the injector and glow plug reside. Every time I run it, I'm still
in awe that the explosion in the pre-combustion chamber flows down the
tiny hole through 5 little ports into the main cylinder without just
blowing it all to hell. You could see the trail of the explosions as
they came out into the cylinder along the head in a 5 pointed star
pattern. I still have a "souvenir piston" of the original 23-year-old
set Stephan presented me, leaving its original piston pin pressed into
one side of the piston, but sticking out so you can see the fine machine
work and quality. The pin has the polish of a fine precision mirror and
you CANNOT run your fingers across its surface and define where the
connecting rod bearing bore the brunt of the blast and moved back and
forth across its surface for 23 years of use. That pin is a true trophy.
The piston top is black, but shows no carbon buildup on it...even not
along the tracks made by the 5 holes blowing out sideways against it
during the "main bang" as it passed TDC...over and over.

The bearings in the bottom were "ok" but I wanted them all replaced.
Stephan started to put the old 23-year-old double-row overhead camshaft
roller chain back against its original tensioning shoe. I said "replace
it, it's old and has gotta be tired by now". Even the shoe, which was a
brown fiber material was just fine! 5 links from that chain were in the
"trophy box". Before his death in a terrible motorcycle accident, he
never let me live down replacing a perfectly good chain...(c;

It sits outside waiting to go any time you're ready. If we're going to
California, I'd like to take it by the shop for an oil change and filter
before we leave. It runs on 20W-50 Rotella T, just like the big boys
rigs. I bought it its 12th monster starting battery 3 weeks ago. Cranks
much easier when all the plates don't have holes in them....(c;

Stick your finger in its exhaust gook and you'll never get it to come
clean. It's always like a greasy lamp black....even before I started
running it on 80% old frying oil and 20% regular gas...which cranks fine
but it hasn't gotten cold in SC at all this year. By Summer, I hope to
be running it on 90/10 with even less thinning gas in it...in the heat.