I've seen a few people mention this, and one or two mention it several times, this is frightening....
What happens when you get a run away is extra fuel is getting into the engine, this can be lube oil getting past the rings, lube oil getting past the valve guides, any fuel leaking into the intake (on other engines leaking lift pump diaphragms leak diesel into the sump, causing "dilution" and raising the oil level, which will eventually lead to a runaway) or just a broken injection system delivering far too much fuel.
Diesel engines, by their nature, will consume ever more fuel and rev ever higher until something breaks, and then that happens all hell breaks loose, I've seen 2 ton flywheels thrown 400 yards before touching the ground, con rods fired through block walls, and the entire bottom blown out of boats.
Listers use very little fuel by their nature, so very little extra fuel will cause them to run away.
Once the "other" fuel supply is sufficient by itself to run the engine, you can take a fire axe to the injector lines, it won't stop it.
Detroits had a "blast"" door on the blower for emergency shutdown, trouble was unless your blower oil seals were in tip top condition they would get sucked in and the engine got all the fuel it could ever use, and vacuum crushed the blast shutters out of the way.
The ONLY (non destrictive, such as a firehose down the intake the hydraulic the pistons and destroy them) shut off method that will work is this....
You need a ROBUST inlet manifold, "robust" = thick walled water pipe or seamless hydraulic steel pipe and it has to make a turn to vertical, on top of this you can mount a LARGE automotive type paper air filter can (ideally with a torque nossle) but most important is the top of the manifold must be inside this air filter can, flush with the bottom, and with a nice big welded on flange at least 1" wide and 1/2" thick, if you weld this flange then it needs to be skimmed flat, you also need to ensure the centre radius is a perfect circle, no protrusions from weld etc
On to this flange you have a sping loaded flap, at least 1/2 inch thick again, ground flat again, with a spring positioned so it will hold the flap shut with a few pounds force, this flap is hinged, in the centre of this flap you have a circle of steel again 1/2" thick (drill a 1/2" hole in the centre and weld to the upper flap) sized and positioned to JUST fit inside the top of the manifold, so you get a stepped door, similarish to the flaps at the top of tractor exhausts, but with the opposite purpose.
How you trigger it is up to you, a cheap and cheerful way would be a lawnmower type centrifugal clutch on the end of one crank.
NEVER try to stop it by putting your hand over the intake, a round peg of wood, a leather cricket ball, things like that "can" work if you have then to hand, the above design was knocked up to shut down engines that were deliberately over run to test various things, and it always worked a treat.
A fire hose will also work a treat, as will and handful of small ball bearings. Never use a small amount of water or a mist or spray, it will just aid combustion, drown that sucker.
YES these will destroy the motor, but trust me, far far far better to destroy the motor while it is still in one piece than letting it throw itself to pieces.
As someone else said, forget manually trying to close a rack held open by hydraulic pressure, you have zero chance.
Also, replace all your fuel shut off valves, especially if you have gate valves, with ball types, though this won't help much on a lister as it is so frugal on fuel
If you are quick enough, a small hand axe or heavy hammer to the injection pipe to fracture it, injection pipes are cheap. Only works if you have a stanley hatched permanently clamped near the motor and never ever removed for any reason.
ROTATING MACHINERY - those flywheels will literally tear you limb from limb, make sure none of your plans involve you going anywhere near them when you are in a state of panic.
Heat, potential runaways, even when caught as our deliberate ones were, generate one hell of a lot of heat, you start that engine again and everything is red hot and giving off fumes and just dying to run away again.
AFTER - YMMV, but if I have anything to do with it a through strip happens next and I discover why it happened then fix it, then check EVERYTHING for any damage done, bolts loosenes, or tolerances shifted.
Listeroid dudes, trust your castings less than I trust my 55 year old Uk castings, particularly when it comes to things like flywheel bursting force....
Might not be appropriate, might not be useful, but, folks I knew who were racing used to paint their highly stressed bits in the hardest and most brittle enamel paints they could find, the paint cracking was an early visual clue.
Wheeltappers used to do just that to loco and railway wheels, cracked, porous and damaged wheels didn't sound the same as sound ones, those flywheels will speak to you and after a couple of months of daily tapping you'll learn that sound
Use your ears and your eyes, this is no good to non and ex smokers, but at various stages of a job we would always sit down, look at the job (or the machine running) and smoke a leisurely cigarette, can't tell you how many times I caught a mistake that way.
Onan generators sucked ( JIC threads suck too IMHO), while big cats with gleaming black paint and show chrome covers looked the dogs bollocks, but that white onan paint job was a godsend for spotting problems.... dark green lister isn't the best colour on the planet, when mine is re-done it will be a light blue...
and finally esther
run aways and near misses are god's way of telling you your maintenance sucked big time, don't bank on getting a second warning.
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which kinds reminds me of an old chief engineers ticket question
Q What steps do you take when the main steam line fractures?
A Fucking big ones, up the companionway ladder. (out of the engine room)