Rolled my 3240, and it ran till it blew ??

[kuboman]

I'm a complete newbie with diesels, but when I turn the key to 'off' on my Kubota L2350 it doesn't do a darned thing. I have to reach down and pull up the fuel shutoff lever all the way to the top.

What could an electrical switch activate (or deactivate) to kill a diesel engine? A fuel shutoff? An air shutoff? Electrically activated compression release? What else? My little tractor doesn't have any of those things. There is absolutely nothing attached to my engine that uses electrical power to keep it running once the glow plugs have warmed it up and the starter has turned it over.

Or maybe I'm mistaken...but the owners manual specifically says you can't stop the engine with the key switch.

If you do not have a solenoid shut off then you must have a cable shutoff. Or sometimes the throttle lever is the shut off.:thumbsup:

 

[firemech]

I agree with those that say you need to shut the air off to stop a runaway diesel. As a retired mechanic from a fire department, all of our diesel fire trucks had mechanical (not electrical) air shut off plates or spring loaded b utterflys in case a truck at a hazardous material call started ingesting flammable fumes. From experience, the spring loaded butterflys worked the best as most plates were basically gravity operated (with air flow assistance) so would not likely operate during a rollover. One additional note however is that some; if running at speed when the emergency shutdown was operated would suck in seals or dislodge air intake hoses and render the shutdown ineffective. I think the CO2 extinguisher might be more effective as it takes the oxygen away without disrupting the actual air flow. Just my opinion
FIREMECH

 

[jagyzf]

Has anyone tried the CO2 proposal? At a high enough temperature even Nitrogen will oxidize in the presence of oxygen (thats where NOx comes from) so I would imagine that a screaming diesel running (rich) on its own oil would have no problem using CO2 as an oxidizer. CO2 works fine on combustion at lower temperatures. Remember that NOx is used as a performance booster for high performance engines.

I could see where plumbing an N2 cylinder directly into the manifold would work reliably, since there is no oxygen to dissociate. Probably a hassle obtaining one small enough though.

Say what???

CO2 is used in fire extinguishers due to it can't be used as an oxidizer and will displace the O2 in an area. It is also why EGR works at slowing and reducing the temps in cylinders. As another said NOx can't either, it is a nasty by product of high temp cumbustion

 

[Don87]

Thanks for the clarification and your opinion, are you sure I am the one not in the know?

How many class 8 truck engines have you worked on in the last 27 years of your life? :

I started working on small engines when I was 12, went on to motorcycles, cars, trucks, dozers, skidders. Held a Pa. Motor Vehicle Inspection License for 5 years before I went into logging, and have been driving tractor-trailer since 2001.

And as to your first question in this, It is not a matter of opinion, my dear fellow............it is a matter of fact.

Read post number 3.........follow the link provided..........and you will gain some valuable knowledge:thumbsup:

As has been stated many times throughout this thread, there are several types of 'shut-offs'.


A solenoid shut-off to stop fuel flow via the fuel pump, will shut off the diesel.

But if the tractor rolls, and the engine oil can get into the cylinders, you now have an unmetered, unstoppable fuel supply(til the oil runs out).........that is a runaway diesel.

 

[Baby Grand]

There are none so dangerous to themselves and the people around them as those who cannot accept that they may be wrong. I have observed this first hand on several occaisions and it always raises the hair on the back of my neck.
-Jim

 

[Don87]

There are none so dangerous to themselves and the people around them as those who cannot accept that they may be wrong. I have observed this first hand on several occaisions and it always raises the hair on the back of my neck.
-Jim

I been there also..........only once, but once was enough.

Dunno which scared me worse, the runaway diesel..........or the steer tire that blew on my rig at 70 mph on interstate 80, a few months back.

 

[JFS2295]

Never saw this thread during the years, but it's interesting. I've watched a couple of run-a-ways in my lifetime.

One was a just rebuilt 2 stoke Detroit. It was being started in-frame when the motor sneezed and started to run in reverse direction. That apparently just totally screws up the governor, or it had other issues. The mechanic kept trying to seal off the intake to shut it down but the material just kept blowing off. He was totally dumbfounded that pressure was coming out the intake. A shop foreman had grabbed a fire extinguisher and stated later he was going to shoot it into the exhaust since he realized what was happening, but the motor grenaded before he got to it.

The second was recent in a NJ Transit bus garage. A unit was pushed in with leaking turbo seals on the motor, but an inexperienced mechanic wanted to start to hear what was going on. Once he rev'd it up she just ran away. They shut of the fuel supply but it didn't matter. The shop just filled with dense oily smoke that smelled like burning rubber until the oil was used up. No one wanted to go near the motor while she was running.

And I've seen the aftermath of a Powerstroke with bad turbo seals.

The situation with the OP is a very rare instance, but the likelihood is raised with the new closed crankcase systems. As mentioned, all a diesel needs is some combustible material in the combustion chambers, and it's not particular if it gets there by injector or intake passages. Whether the combustible material is motor oil or released gases, the motors power and rpm are limited only by the quantity of material entering in through the intake passages. You can shut off all the electrical and diesel fuel you want, and you could even take an axe to the diesel fuel lines, but she is going to run. Totally ungoverned by anything engineered into the motor.

If you want to protect your 4 stroke diesel from the very, very rare run-a-way, the intake closure valve is the best solution. "Allie" my dozer over to the left has a singing Detroit 2 Stroke in it and uses an intake closure valve as it's shut off. Very simple; very effective.

Edit with picture of shut-off pull knob in the center of the dash.

 

[V1Rotate]

I agree with those that say you need to shut the air off to stop a runaway diesel. As a retired mechanic from a fire department, all of our diesel fire trucks had mechanical (not electrical) air shut off plates or spring loaded b utterflys in case a truck at a hazardous material call started ingesting flammable fumes. From experience, the spring loaded butterflys worked the best as most plates were basically gravity operated (with air flow assistance) so would not likely operate during a rollover. One additional note however is that some; if running at speed when the emergency shutdown was operated would suck in seals or dislodge air intake hoses and render the shutdown ineffective. I think the CO2 extinguisher might be more effective as it takes the oxygen away without disrupting the actual air flow. Just my opinion
FIREMECH

Has anyone ever used a Co2 extinguisher to kill a diesel?
Because of the huge volume of air that is ingested into the intake with the engine at high RPM, I suspect that unless you get 100% of the Co2 into the intake with no ambient air also being sucked in the engine will only be drawing in a partial mix of Co2. I think this might only slow the engine down and not completely kill it. Also, Co2 is extremely cold, I wonder about thermal shock to a hot engine.

 

[o2batsea]

While a runaway may be spectacular it doesn't mean the death of the engine as the OP found to his relief. Several of my off-roading acquaintances have rolled their trucks and had them run away with no ill effects save for the need to replace all the lubrication. If done often enough though it will eventually kill the motor as it gets starved for oil as it reaches the end of the event.

 

[Johnbro]

Say what???

CO2 is used in fire extinguishers due to it can't be used as an oxidizer and will displace the O2 in an area. It is also why EGR works at slowing and reducing the temps in cylinders. As another said NOx can't either, it is a nasty by product of high temp cumbustion

C02 is what you get when you completely oxidize (ie burn) carbon. Because it's completely oxidized, it's nice as a shielding gas for fire extinguishers or welding, or for adding bubbles to your favorite beverage.