Runaway Diesel

[Colin A]

While working at a boatyard winterizing an old universal or westerbeke, had it run away. Luckily the fuel kill lever worked to shut it down after about 15 sec. So not much drama. I had a teacher who was in the Army transport corps back in Vietnam, he was an engineer on a tug. They had the big ancient diesel runaway on them once. He told me he tried throwing rags and shirts down it but it just ate them. He had shut off the fuel but it was running on the oil at that point so he threw some chunks of scrap metal down it which jammed in the valves and got it shut down. He said he got scared as the noise got awful as the RPM climbed well over the 1,000 or so it was rated for.

[Diesel Bill]

Originally Posted by Pauls

Some of the old GM diesels had a spring loaded plate which would snap over the intake and choke the engine. All that was required was to pull a lever to actuate the plate. Positive, fast, and simple.

Reminds me back in the 1970's while working at International Harvester in San Francisco, I got sent on a service call to the mouth of the Caldecott Tunnel.
A semi truck pulling flat bed doubles was dead in the entrance to the tunnel.
It had an 8-71 Detroit Diesel and when trying to start would cough, shake and blow solid black smoke but not run. The air shut off latch was in the latched position but the roll pin was sheared allowing the spring to turn the shaft closing the damper plate. Used a pair of vice grip pliers and a coat hanger to hold the shaft in the run position till the truck could make it to the shop and replace the roll pin. The CHP was glad to see that truck gone.

[Pauls]

Zee, and others inclined to want to test an emergency shut down, which I think is an excellent idea, by all means go ahead and test what you think you want to use if you have a run away. I will caution that whatever you use to stop the air intake should not risk having the engine suck junk into the motor. Zee, I'd kind of expect the suction would collapse your K and N. Assuming it's mounted on an intake tube, you could keep a screwdriver by the engine to loosen the filter, pull it off, and then a flat plate pressed against the tube will kill the engine. It's another aspect of good seamanship.

[Pete7]

I don't think anyone should be putting fingers or hands anywhere near a runaway engine and certainly not the air intake. Self preservation should hopefully keep most people well away from a large lump of steel that is quite likely to go bang very quickly.

Pete

[Wotname]

Originally Posted by Pauls

Zee, and others inclined to want to test an emergency shut down, which I think is an excellent idea, by all means go ahead and test what you think you want to use if you have a run away. I will caution that whatever you use to stop the air intake should not risk having the engine suck junk into the motor. Zee, I'd kind of expect the suction would collapse your K and N. Assuming it's mounted on an intake tube, you could keep a screwdriver by the engine to loosen the filter, pull it off, and then a flat plate pressed against the tube will kill the engine. It's another aspect of good seamanship.

Testing an emergency shut down technique is (IMO) a good idea. It can be tested safely on a normally running engine until the technique is well practiced and understood. This should stand you in good stead for dealing with a genuine runaway situation.

Originally Posted by Pete7

I don't think anyone should be putting fingers or hands anywhere near a runaway engine. Self preservation should hopefully keep most people well away from a large lump of steel that is quite likely to go bang very quickly.
Pete

While I agree to some extent, proper perpetration and (self) training should mitigate the potential risks.

Doing nothing may exacerbate the situation to the extent of sinking your boat or at least causing more serious injury when the engine destroys itself.

[Wotname]

I was next door to a small rural power station when their brand new diesel genset (some sort of turbo V12 diesel) ran away after it's first 50 hour service. All the emergency shut down functions failed and the power station was evacuated. After about four minutes, the engine threw a rod or two and stopped.

The legal teams had a field day...

[DumnMad]

Fuel shut-off would be my 1st reaction but if its oil burning that would be no use.
Next according to advice above is to shut off the air.
So whats the preventative action against oil burning?
1. Don't overfill the oil sump.?
2 Don't run a badly smoking engine ?
??
??

[Wotname]

Originally Posted by DumnMad

Fuel shut-off would be my 1st reaction but if its oil burning that would be no use.
Next according to advice above is to shut off the air.
So whats the preventative action against oil burning?
1. Don't overfill the oil sump.?
2 Don't run a badly smoking engine ?
??
??

Decompression levers (if fitted).

[ggray]

Originally Posted by Pauls

Some of the old GM diesels had a spring loaded plate which would snap over the intake and choke the engine. All that was required was to pull a lever to actuate the plate. Positive, fast, and simple.

They certainly did, but I was told that if that emergency shut-off was used (at what rpm I don't recall) the resulting engine vacuum would damage some component (can't remember what component either). Of course, this would be preferable to damage from not stopping the engine.

An incident I recall happening was soon after they started selling gasoline with alcohol added. A tanker being loaded at the terminal had its diesel engine running while being loaded, and when the alcohol fumes drifted down to the truck, that engine took off until it blew up. Policy after that was engines had to be shut off.

[a64pilot]

Originally Posted by DumnMad

Fuel shut-off would be my 1st reaction but if its oil burning that would be no use.
Next according to advice above is to shut off the air.
So whats the preventative action against oil burning?
1. Don't overfill the oil sump.?
2 Don't run a badly smoking engine ?
??
??

About the only way an engine will run on its own oil is of its way overfilled, then the crankshaft will beat the oil into a foam, the foam will fill up the engine and come out of the blowby tube, that is of course plumbed into the suck side of the engine.
Another way is to have fuel leaking into the oil, this will raise the level until eventually it’s high enough to come out the blowby tube.

Almost always an engine with enough blowby to blow enough oil out of the tube to make it run away, has such a low compression that you can’t get it to start, and if you do it fills the area with blue smoke, meaning of course your unlikely to be running the thing to begin with.

Now if it were me, and especially if I were running a turbo, I would not plumb the blowby tube into the suck side of the engine, that is in my opinion pretty stupid, I’d instead run it into a catch can, reasoning is I don’t want to be feeding oil mist into my turbo and intercooler, nastying the things up. But if a blow by tube is not plumbed into the suck side, the engine can’t usually run away from oil.
I say usually as in my younger days I flipped a farm tractor over on myself, and it tried to run away as it was upside down and enough oil was getting past the pistons to run, but it ran poorly and eventually quit after I turned the fuel off.

[Fence Man]

Originally Posted by Pete7

I don't think anyone should be putting fingers or hands anywhere near a runaway engine and certainly not the air intake. Self preservation should hopefully keep most people well away from a large lump of steel that is quite likely to go bang very quickly.

Pete

While possible, it's usually not quite that violent.

[capngeo]

Originally Posted by Pauls

Some of the old GM diesels had a spring loaded plate which would snap over the intake and choke the engine. All that was required was to pull a lever to actuate the plate. Positive, fast, and simple.

Those old GM 2-stroke diesels were prone to runaway, hence the factory solution. Modern diesels are fairly immune to this phenomenon (electronic controls and common rail).

As others have said, the most effective way to stop ta runaway is a CO2 extinguisher. Shutting off the fuel often fails as they will pull oil out of the crankcase.... especially if a large vacuum is created by restricting the air intake; if you do try to smother a runaway be SURE it is complete occlusion.

[capngeo]

Originally Posted by a64pilot

About the only way an engine will run on its own oil is of its way overfilled, then the crankshaft will beat the oil into a foam, the foam will fill up the engine and come out of the blowby tube, that is of course plumbed into the suck side of the engine.
Another way is to have fuel leaking into the oil, this will raise the level until eventually it’s high enough to come out the blowby tube.

Almost always an engine with enough blowby to blow enough oil out of the tube to make it run away, has such a low compression that you can’t get it to start, and if you do it fills the area with blue smoke, meaning of course your unlikely to be running the thing to begin with.

Now if it were me, and especially if I were running a turbo, I would not plumb the blowby tube into the suck side of the engine, that is in my opinion pretty stupid, I’d instead run it into a catch can, reasoning is I don’t want to be feeding oil mist into my turbo and intercooler, nastying the things up. But if a blow by tube is not plumbed into the suck side, the engine can’t usually run away from oil.
I say usually as in my younger days I flipped a farm tractor over on myself, and it tried to run away as it was upside down and enough oil was getting past the pistons to run, but it ran poorly and eventually quit after I turned the fuel off.

That is not correct; they will pull oil past the rings and valve guides.

[Snore]

Originally Posted by DumnMad

Fuel shut-off would be my 1st reaction but if its oil burning that would be no use.
Next according to advice above is to shut off the air.
So whats the preventative action against oil burning?
1. Don't overfill the oil sump.?
2 Don't run a badly smoking engine ?
??
??

Best idea was shoot fire extinuisher(s) into intake. No oxygen- no combustion

[a64pilot]

Originally Posted by capngeo

That is not correct; they will pull oil past the rings and valve guides.

As I said before, any engine that is burning enough oil that it can run on, much less run away, is an engine that burns oil so excessively and has such low compression that it’s unlikely to start to begin with and will smoke so badly that your not likely to be running the thing if you can get it going.
Think about it, an engine that burns a quart of oil every ten hours of so smokes pretty bad, how bad will it smoke if it’s burning a gallon of oil an hour? How did it get to the point of burning that much oil and yet was still being used?
Anything is possible, but I have never seen it.

I’m not sure the fire extinguisher would work myself, it may be that at high RPM an engine will inhale and exhaust the entire contents yet still be turning enough RPM to accelerate after the CO2 is exhausted?
I know a piece of wood, even a paperback book over the intake will work though, just do not use a body part, the vacuum is so strong it will damage your hand etc.