Runaway Abatement Question

[nzzshl]

It occured to me that I have seen posts regarding the topic of runaway diesel engines and often, the associated answers of what to do in the event of such. Obviously, ignition requires the three components of combustion: Heat, Air & Fuel. Removing any one of the three results in collapse of the combustion process. In the case of the runaway diesel engine, the fuel becomes the engine oil, the heat is obvious and the air remains flowing......I've seen the typical response of to cut the air supply. My question is this, if the engine began a runaway condition, why couldn't the observer discharge a the full content of 15 pound capacity CO2 cylinder into the air induction system? Using a Kidde 15 CD CO2 Fire Extinguisher for example, at full dump, the contents last for approximately 27 seconds. IMHO, the duration should be sufficient to permit full crankshaft wind-down to occur before the extinguisher expires. I am wondering that for the $275 that the Kidde extinguisher costs, it might be a valuable item to have in the barn, not to mention for the possibility of convention structure fires.
I'd like to have other members weigh in on the topic. Excusing the term, "Fire Away"!

 

[nzzshl]

As a correction to the initial post, I have determined that the average discharge time of that particular fire extinguisher is 12-14 seconds, a 20 pound unit lasts 15 - 17 seconds. I apologize for the error in the original discharge-time statement. Regardless, is 12-17 seconds of discharge enough time for the engine to stop the overrun? I still think it is.

 

[Dave_eng]

Using a CO2 extinguisher is a common way to stop a run-a-way but not many have one of those on hand. Trucks that deliver gasoline to service stations sometimes have an air valve on the engine air intake which can block off the air thus stopping the run-a-way.
Never use your hand to try and block the air. You can be badly hurt.
Unless your engine is in bad shape with worm rings or has a problem with the crankcase vent system freezing up then you are quite unlikely to have this happen to you.
Dave M7040

 

[coachgeo]

IMHO easiest is to cut off the air (Oxygen) source and putting a valve structure into the air intake is not that difficult and significantly cheaper that what proposed here.

Have proposed an RV holding tank dump valve in a previous thread on this topic while another suggested similar but more heavy duty valve from exhaust bypass setup.

RV Dump valve: http://www.orangetractortalks.com/forums/showpost.php?p=148781&postcount=13

Exhaust bypass: http://www.orangetractortalks.com/forums/showpost.php?p=148813&postcount=15

 

[North Idaho Wolfman]

Know where the air intake is and have a plate of wood, steel or aluminum to block off the air.
Kubota's rarely run away with themselves.

 

[sheepfarmer]

Can you usually drive the tractor safely a little distance under runaway conditions? Eg pull it out of the barn or away from some other structure? How safe to work around the front of it to get the hood lifted to get to air intake? How close would the fire extinguisher have to be to be effective? Would it work to blast it at the vents on the side where the air intake is located? (Miss the design of the 8N where everything is just right there out in the open).

 

[coachgeo]

Can you usually drive the tractor safely a little distance under runaway conditions? Eg pull it out of the barn or away from some other structure? How safe to work around the front of it to get the hood lifted to get to air intake? How close would the fire extinguisher have to be to be effective? Would it work to blast it at the vents on the side where the air intake is located? (Miss the design of the 8N where everything is just right there out in the open).

Could you move it..... hmmm. Don't think you could get it in gear but I could be wrong. Say that cause the RPM's are running away too and it may be too much for typical gear selecting. In fact letting out the clutch with that high of an RPM is liable to damage something else I would think.

As to moving hood etc., yeah you can do it but it takes nerves of steel cause the racing engine makes you feel it is going to EXPLODEEEEE. It is quiet a phenomenon. Have done it though.

Blowing something else at intake to replace the air.. not sure if one could do that effectively thru the hood vents or not.

 

[Shadow]

If you have a run away motor, you leave the area, dont try to stop it. You aren't going to do anything to keep it from doing any less damage. If it runs away, you're going to have to tear it down for a rebuild anyways. It's not worth risking your life to stop.

 

[CaveCreekRay]

I like the simple Emergency Procedure someone else mentioned: LOAD UP MACHINE.

We are only dealing with 30hp or under here. If you are on dirt, drop your implement if installed, drop your FEL, if installed. If a manual transmission, select a high gear with all this equipment down and further load the engine.

For those of us with HSTs, if we are underway, we'll never hear the engine run away over the HST noise.

 

[nzzshl]

Hey, thanks to all that responded.............the comments included many viable solutions. The event of a runaway condition does seem unlikely, although I often seem to be the subjected party to statistical improbabilities.

Chuck

 

[olthumpa]

To prevent a runaway engine only keep a small amount of oil in the engine, that way it will not be able to run very far.

 

[Lil Foot]

To prevent a runaway engine only keep a small amount of oil in the engine, that way it will not be able to run very far.

So, no oil in the engine will prevent it completely.
I'm sorry, I couldn't help it.

 

[ShaunRH]

Non-turbo engines usually have a hard time going full nuts runaway as whatever oil can seep by the rings isn't enough to run the motor well. If you have a valve guide go bad, it can be worse but it's not normally vaporized enough to go nutso and it's usually just one piston. It is possible to have it go fully haywire but you can always stall it out (if your clutch is in good shape) as has been previously said. A clutch is far cheaper to replace than a motor.

Turbo charged motors are the one at serious risk for runaway. They lose the oil seals on the turbocharger and it just pumps oil into the compressed air stream and the engine launches. You have to use a block of wood or plate to shut it down. I've seen the youtube videos of guys doing it with rags but that's almost suicide with your hand. The CO2 fire extinguisher works too.

If you are really worried about it, just get the cable exhaust diverter and put it in line on the intake, call it a $100 insurance policy.

 

[ZoomZoom71]

Runaway diesel. Haven't heard that term since the Navy.

 

[coachgeo]

Non-turbo engines usually have a hard time going full nuts runaway as whatever oil can seep by the rings isn't enough to run the motor well. ....

Oil leak into cylinders is not the only reason this happens. Though technically not a "run away" situation there has been a few in here bringing tractors back to life that have had stuck racks that took the engines to wide open at start up and their set ups gave them no way yet to shut the down.

Also if one unknowingly had an IP leaking fuel into the cylinders dieselizing the lube...... even on a non turbo, that will also result in a run away engine once it finds a way to start combusting it.

Granted these two scenarios are again more liable to happen when someone is attempting to bring an old tractor back to life that they don't know much about it's history. In those cases a block of wood kept near by is more logical than installing a valve.

 

[ShaunRH]

Oil leak into cylinders is not the only reason this happens. Though technically not a "run away" situation there has been a few in here bringing tractors back to life that have had stuck racks that took the engines to wide open at start up and their set ups gave them no way yet to shut the down.

Also if one unknowingly had an IP leaking fuel into the cylinders dieselizing the lube...... even on a non turbo, that will also result in a run away engine once it finds a way to start combusting it.

Granted these two scenarios are again more liable to happen when someone is attempting to bring an old tractor back to life that they don't know much about it's history. In those cases a block of wood kept near by is more logical than installing a valve.

Agreed, and my comments were directed at folks concerned about runaway on an engine that they own, as an insurance against it... not as restoration solution. There are several things that can cause it in that condition, as you pointed out, but in a regularly running, naturally aspirated engine they are far more rare.

I think the human condition is really what we are looking at here, as we all fear the runaway condition from many aspects (safety, cost, sheer terror... ) so, that it's haunting your mind, either your modified RV waste gate or the exhaust bypass butterfly valve would give someone peace of mind.

For turbo charged engines, the butterfly valve should be standard issue from all manufacturers, but I'd certainly add one if I had such an engine. I have had a CAT 6cyl turbocharged 100KW generator diesel go runaway on me and watched it bend the crankshaft, pop a chunk out of the block and make a really big mess. I wouldn't want to repeat that, and had I not been far enough away from it when it did it, I'd have had to change my shorts. It wasn't fun, so I understand the fears entirely!

 

[ItBmine]

Easily shut down by blocking the air intake.

I've had two-stroke V6 and V8 Detroit Diesels run away on me a few times. That's why they have an air shutoff on the blower.