WAIT A MINUTE where is the starting voltage coming from I thought
diesels started from a electrically heated glow plug. I know
NOTHING about diesels but, it seems to me, starting an engine with a
compression ratio of 400 psi, should be harder than my old 60' Ford
Falcon stick, unless there is some sort of piezo electric effect.
Are you saying pushing a cold diesel, with no battery, down a sloped
driveway would compress the fuel enough for it to combust?
Nope, direct injection diesels just have a lot higher compression ratio
than prechamber/glow-plug diesels, and can start without aid because the
air in the cylinders gets much much hotter just from compression.
Sometimes a heater is added in the intake plumbing (eg. Dodge Ram) so
that the driver doesn't notice longer crank times at lower temps, but
its not really necessary. Just a luxury.
Glow-plugs make starting a cold diesel easier, but they *ARE NOT* vital
to the process - Case in point: an 80-something F350 diesel that we use
for grunt work here on the ranch. Its glow-plugs (and in fact, the
entire wiring harness that used to power the glow plugs) are toasted,
and have been for years. Result: Y'gotta crank it and crank it and crank
it and then crank it some more, and perhaps even crank it a little bit
more than that before it fires on the first start of the day, but it
runs just fine. Once there's some residual heat in the block/heads from
the first run of the day, you can shut it down, and it will restart so
quick you'd be left totally clueless about the fact that the glow-plugs
"Your falcon must have a timing issue" is about all I can say. Gas
engines with a stick behind 'em are, in general, kiddy-play to
push-start unless the timing is off. As a prime example, my '82 Mazda
626 push-starts in reverse with three feet or less of backwards roll, or
in third with about 8-10 feet of forward roll - first time, every time,
no sweat at all.
That's *EXACTLY* what's being said. The key is getting the air in the
cylinder compressed quickly enough to produce an in-cylinder temperature
that's at or above the flash-point of the fuel. Glow-plugs (and the
associated wiring/power supply) make the process easier by raising the
head/block temperature, which in turn raises the temperature of the air
charge in the cylinder, but they *ARE NOT* mandatory. The same effect
can be achieved (and in fact, this is specifically recommended in some
cases) by playing a blowtorch on the head for a while before trying to
start the engine.
Lemme give the old diesel a push to get it rolling down the hill, and
I'm gone... :)
Fact: Some heavy equipment with diesel engines, like 2 of the 3 ancient
(30s? 40s? 50s? They truly are ancient beasts) dozers our hay grower
uses for farming his rice, have *NO* electrical system whatsoever on
them. *NOTHING* electrical. They don't have a single wire, no
alternator, no generator, no battery, no cord to plug into 110 or 220,
or any other kind of electrical stuff on the main engine. They DO have a
"pony motor" alongside, which, in this particular case, runs on gas (and
as such, has the requisite electrical ignition system to make a spark)
and starts by way of pure human power - either hand-crank like an old
Model T, or pull-start like a lawn mower, depending on which of the two
you're trying to fire up. Neither one has anything that even resembles a
glow-plug, although I have seen cases where the exhaust from the pony is
routed through galleries in, or ductwork around, the head to perform
exactly the same function glow-plugs would serve. To start either one of
these two Cats, you start the pony, by either cranking or pulling as
needed, get it running happy, pull a lever, and the pony spins the main
engine until it fires. Then you crawl down on the track, shut down the
pony, and go about the day's work.
Alternatively, there are the "air-start" versions - they start from
compressed air supplied by either a pressure tank that they pump up
while they're running, or an external air compressor. Again, not a wire,
battery, alternator, or glow-plug to be seen anywhere on them.
In summary: With a diesel that isn't computer-controlled, electricity,
in any form, is *COMPLETELY* optional. Nothing about them requires
anything electrical to be attached for them to run, although having
glow-plugs does tend to make starting them for the first time each day a
fair bit easier.
Don Bruder - firstname.lastname@example.org <--- Preferred Email - SpamAssassinated.
Hate SPAM? See <http://www.spamassassin.org for some seriously great info.
Y'gotta crank it and crank it and crank
it and then crank it some more, and perhaps...<<<
This can ruin the engine. Get enough unburned liquid into the tiny compression
chamber of a 20:1 engine and eventually something will happen. "Something" may
either be starting, or a bent connecting rod, or a blown head gasket.
425 White Horse Pike
True, Also while in the army (British) I used to hand crank old generator
sets 7 & 12.5 Kva, summer time that is, winter time put an old oily rag in
the air filter place and set it alight, then crank her good. These did use a
pre-compression lever, to relieve the compression of the engine untill you
got up to speed and let it go. They usually started with a big black cloud
of exhaust and took a few minutes to get up to speed, but they did run for
: > After listening to last weeks puzzler, and hearing the answer on Car
: > was wondering if a diesel engined car could really run with a dead
: > electrical system.
: > http://cartalk.cars.com/Radio/Show/Audio/200350/RA/s05.ram
: > Even though it is true that a diesel has no ignition system, I have
: > assumed that a diesel still used some kind of electrically operated
: > system for the fuel pump. After all, even diesel cars have what would be
: > regarded as an "ignition switch" in a gas powered car. Even though I
: > that a modern diesel could run without electrical, I suppose it is
: > that older diesels had some kind of mechanical linkage that controlled
: > fuel pump. Any comments?
: > Robert
Yes, this can happen. In fact, it happened today - the negative terminal cable
came loose and off of the battery terminal, and as such I lost all electrical
functions - no radio, lights, signals, wipers, NOTHING. But I still had power
steering, brakes, and the engine ran without complaint. Scary stuff.
: After listening to last weeks puzzler, and hearing the answer on Car Talk, I
: was wondering if a diesel engined car could really run with a dead
: electrical system.
: Even though it is true that a diesel has no ignition system, I have always
: assumed that a diesel still used some kind of electrically operated control
: system for the fuel pump. After all, even diesel cars have what would be
: regarded as an "ignition switch" in a gas powered car. Even though I doubt
: that a modern diesel could run without electrical, I suppose it is possible
: that older diesels had some kind of mechanical linkage that controlled the
: fuel pump. Any comments?
I believe youi have the aluminum head, so if you can't find any leaks
then you probably have a warped head leaking coolant into the combusion
chamber, which burns it out so hot you don't see the moisture in the
exhaust fumes. I had a similar problem with a 242 Volvo, I pulled the
head off, got a fine tooth flat file, and carefully shaved the high
spots off the head with the flat file. (For all you naysayers, this
technique will not gouge the surface of the head). Then I put it back
together with a new head gasket, tune up and so on and my water usage
problem was solved with many, many more miles on the engine.
Robert Calvert wrote:
Absolutely no electrical power is needed for a diesel engine to work, as
long as there is fuel, air and a way to start the engine. Modern diesel use
an electrical pump to transfer fuel to the high pressure injection pump, but
it is not really needed. Same goes for control system of the HP pump.
Engine, like in a modern pick up, will have a electrical motor to control
the fuel HP pump, but it is strictly an accessory, and a replacement for a
throttle cable / also an easy way to meet emissions, because it can be
controlled by a computer. When you turn off the key on a car, you
de-activate a fuel shut off solenoid. Convenient but not necessary for the
Martin's Marine Engineering Page
I used to drive a dumper truck which had a single cylinder diesel engine fed
by gravity from fuel tank. You had to crank it relly quickly while keeping a
big valve in the head open then suddenly close the valve to allow the thing
to work. No electricity anywhere and no fuel pump either.
The statement in the Puzzler set the time as 1974 and said that the car was
"about 14 years old and had fins". The ALT light came on when the belt
broke. I agree that the engine would run until turned off. Where I think
the puzzler was wrong is that in 1960 MBs had generators not alternators if
my memory serves. I had a 1960 190C -not a diesel- but I think there was a
190D and there may have been a 240D.
Only relatively recent diesels with things like computer-controlled
injection or HEUI (hydraulically activated electronically-controlled
unit injection) need electrical power to run. Many older ones did have
an electrical solenoid to hold the fuel supply open, but other than that
would run with no electrical power. Most older machinery diesels had a
mechanical cable to shut down fuel and could run with absolutely zero
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