Engines that run out of control

I have a well worn 6-71 that runs ok with the blower flap closed, just smokes a little more.

terex herder said:

I have a well worn 6-71 that runs ok with the blower flap closed, just smokes a little more.

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Probably needs to have it adjusted so it seals better. Also sometimes those flaps get rusted/corroded from lack of movement and when needed to work they don't.

I wonder if spraying a fire extinguisher in the air filter inlet would stop a run away?

They say a CO2 extinguisher will stop it, but as long as some engines keep spinning after you shut them down, I have my doubts, because if the extinguisher ran empty while the engine was still rotating, it would be right back off to the races.

Birken Vogt said:

They say a CO2 extinguisher will stop it, but as long as some engines keep spinning after you shut them down, I have my doubts, because if the extinguisher ran empty while the engine was still rotating, it would be right back off to the races.

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And I would not like to think what would happen if someone did not understand that the idea is to use a CO2 and not Dry Chem extinguisher. Guess it would be better than the damage done if it grenaded!

The old halon extinguishers would probably work well but here they are not legal anymore and I haven’t seen one in years

I have not had a diesel run away, but I have found a broken mag wire the scary way on an aircraft engine. you do a fuel cut to shut down the engines, but sometimes there is a bit of pressure in the fuel injection distributor that leaks down into the inlets on the heads.
My batteries were marginal so I propped it through a couple of blades and BAM!
That engine propped itself through a couple of blades
I was propping it the right way with the tips of my fingers and body position in the safe zone, but none of that mattered as far as scaring the crap out of me.
Just like trailer brakes all it takes is one broken wire to ruin your day.

The 12V 71 That would not shut down had a relay with fused Contacts sending power to the Fuel solenoid. When the relay was pulled and as I opened the fuel lines it shut down. Did rebuild both blowers and unit ran okay afterwards. The speed did not go too much above 2000 rpm but could have. Thinking very fast as it happened.
Simon C

In my early days as a mechanic I worked for a crane and rigging company. The upper in an old P&H had a 6v53 that was a constant problem. Their decision was to repower with a 6-71 out of an old truck. We drug the chassis up by the shop, checked fluids etc. 5 gallon can of fuel and some batteries were setup for a test fire. It must have been a slow day because there were 5-6 operators and riggers standing around when we spun it over. Coughed a time or two and once it got the air bled out she was a moonshot! WFO, fan going 90 to nothin, belts shredding, chunks of the fiberglass hood flying off, wasps coming out of their nests wondering WTF just happened.

Riggers and operators scattered like a squirrel being chased by a dog. The old shop foreman pulls his smokes out, lights one up and watches it for 10-15 seconds and makes a motion to me like he was pulling the fuel hose out so that’s what I did. When it finally ran out of fuel it sounded like a tornado siren winding down. I was so captivated by what was happening I didn’t move a muscle. I was covered in dirt, chunks of belt and fiberglass. It was one of the coolest things I’d ever seen!

After it got quiet Bill took another drag and said grab your tools kid, let’s pull it out. I’d say it’s a good one.

First was at Nashville Diesel College. One group did something wrong and they had a screaming Detroit. Everyone fled but the instructor. I watched around the corner of the bay door as he cut the fuel line and walked away.
Second was a BC1 Cummings. Did an engine swap and it ran away. Put a 1/4 steel plate over the turbo and it kept screaming for a while. This happened 2 or 3 times. Finally figured out a dirt dobber had stopped up the fuel return line.
Third was a Mack. Turbo went out and was towed in. Asked the company if they wanted to pressure wash the CAC out, take it to a radiator shop or replace it. No just replace the turbo. Started it up and away she went. Ran for several minutes with the stop cable pulled running on oil from the cooler. When the RPM's got really high the valves would float and slow it down for awhile. Then take off again.
The one before first was a primative skid steer type machine. It was very narrow. I did not follow directions and had the bucket up while traveling. It turned over on its side. Ran away from the oil bath air filter. I got that apart and shut down PDQ.
There were some others along the way but they were low pressure as shut down quickly.

Actually any kind of inert gas would work to shut one down. As well as very carefully administered H2o, only in extreme emergency of course, would be easy to over do it and hydro lock.

Something I forgot to mention. If you are on a Detroit, you should fear a runaway every single time and be prepped for it. I always have a pair of vise grips already adjusted and ready to clamp a fuel line, a hammer in case the vise grips aren't enough, and most the time if I can get a/the valve cover off, I have a pair of vise grips on the fuel rack tube. 1 or a combination of these will get one shut down pretty quick. I don't trust the emergency flaps, never have.
If you have a engine that has the flap, make sure it works BEFORE you start! I have seen many of them wired open and not usable.

The place i worked had alot of Detroits i was told about them so i was very careful and never had a problem. There was a older guy i know that had worked on some kind of stand by engines that were under ground. He said he would have the intake hose off and a big book ready. One started running away he sat the book on the intake and it started eating it so he got clear and let it go.

Actually, any time I work on an injection pump or governor on any engine, I always pull off the air intake hose at the engine and have a piece of 1/4” steel plate ready to slap over the intake if the need arises.

56wrench said:

Actually, any time I work on an injection pump or governor on any engine, I always pull off the air intake hose at the engine and have a piece of 1/4” steel plate ready to slap over the intake if the need arises.

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Forget who told us about it but many many years back we had a pair of 1/4 inch steel plates made up with handles welded to them so if the need came you could slap them on the intake without having to worry about getting fingers trapped between plate and intake.

Would not like to think about getting fingers caught and not be able to get away from a screaming 16V-71 or D399 Cat!. We needed two as many of our engines had twin turbos or blowers. In 40+ years don't think I ever needed to use them, but still felt better knowing they were there!

Very few instances with runaways, I can attribute that to electronically controlled fuel systems and facility engineering. I was working on alternative fuel development. I was the one operating the test unit and performing hardware changes. Well I was needed else where that morning. I left it to the engineer to give the replacement operator a lowdown on how to meter alternative gaseous fuel, in addition to all other engine control parameters. Development on this was a knife edge, give and take, boundary limit testing scenario.

The replacement guy did a great job until it was time to shut the gaseous fuel off. Normally setting a "0" to the parameter would bring the system back to original maps, that was the case with all the engine parameters except the gas valve. "0" translated into the valve not knowing what to do, so it went wide the fudge open. The engine was at rated power conditions when this happened and monster slug of hydro carbons enters the combustion chamber.

Away we go.

Hit the big red button.

The facility components were enough to suffocate her and bring the angry beast to a standstill.

Needed new lower rotating components, liners, head gaskets, spacer plates. The operator apologized to me so many times, It wasn't his fault.

I've got another one from a co-worker that i could butcher if anyone is interested. Hopefully i don't get a call saying I violated some confidentiality agreement I signed years ago.

I know of an outfit near by that in the past has done CNG testing, but mostly on EMD engines. That would be a fun one to deal with in a runaway condition. I would want a huge bank of Co2 and individual inlet port distribution for peace of mind, and to save the engine and the building in case something goes wrong. I think the only way to violate confidentiality is to explain all the technical working parts of the system. You may actually find that they disclosed much of what you did either for patents or at a big expo meeting of the minds etc. especially if it was 5 or more years ago. If they have a website look on that and see if and what they may have disclosed there. I'd like to hear more stories of that sort of work.

chidog said:

I know of an outfit near by that in the past has done CNG testing, but mostly on EMD engines. That would be a fun one to deal with in a runaway condition. I would want a huge bank of Co2 and individual inlet port distribution for peace of mind, and to save the engine and the building in case something goes wrong. I think the only way to violate confidentiality is to explain all the technical working parts of the system. You may actually find that they disclosed much of what you did either for patents or at a big expo meeting of the minds etc. especially if it was 5 or more years ago. If they have a website look on that and see if and what they may have disclosed there. I'd like to hear more stories of that sort of work.

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An old Co-Worker's experience that was pretty infamous in the shop

Just like anything else engine development was a different world years ago when this happened. We learned from mistakes, this being one of them. There was a test facility where the operator's console was in a mezzanine above the engine, you would have to walk past the test bed to exit the building. Back then you would walk next to a screaming stationary engine without a second thought, still do in most of the world I imagine. The console was populated with an operator and engineers running the test. The facility had emergency shutoffs tied in to E-Stops. Intake air, exhaust and fuel would be shutoff, obviously that works well and great for controllable engines. The 8 cylinder engine being tested was the largest bore we traditionally run - 280mm or about 11", its about the size of a medium/smaller box truck. The engine has a rear mounted turbo and it has a huge oil sump 200~ gallons.

This application was using a drive line coupling between the engine and the dyno. To contain the coupling there is guarding in place as you would expect.

The coupling failed causing a sort of violent mechanical windmill effect. As the coupling was making its rounds it mangled the coupling guard, smashed the turbo oil supply, and the intake manifold. The turbo oil supply was then feeding the inlet manifold making the e-stop irrelevant.

The operators console was full of engineers collectively soiling themselves weighing the option of staying put above the engine or running past the self-destructive violent rotating mass to exit. I am pretty sure they decided to stay put.

Just remembered a dumb thing I did once, okay sure I have done many over last 71+ years, but this one is on topic!

Was tasked with replacing the injectors in a Euclid R-35 with a 12V-71. Job went pretty good till the point I went to fire it up. Pushed in the shut down cable and hit the starter button. If you're smart you know right off what I did wrong! Yep this dummy adjusted the rack with the shut down pulled out! Only thing that saved me and that engine was the emergency shut sown cable was not seized and the flappers on the top of the blowers were functional as opposed to my brain!

Managed to kill it before RPMs got too high and proceeded to run the rack adjustment a second time this time with shut down cable in the run position.