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JointHorse posted:So.. what the hell happened there? Turbo failure and thus engine runaway? I would imagine the injectors getting stuck to "on" would do it. Not sure if that's actually what did happen or if it even could, but from my understanding of diesels that'd be about the effects. I like the pop from the radiator before it finally melts into a huge hunk of slag.
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Nov 17, 2009 21:45
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no, its sucking in oil which happens when the crankcase is overfilled. the oil ignites on the compression stroke, like diesel, and so the engine keeps running. there really is no way to kill it other than running into a wall or dropping it into 5th if you have a manual. The awesome part is, the engine will keep going faster and faster until it kills itself.
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Nov 18, 2009 00:15
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Frank Dillinger posted:no, its sucking in oil which happens when the crankcase is overfilled. the oil ignites on the compression stroke, like diesel, and so the engine keeps running. there really is no way to kill it other than running into a wall or dropping it into 5th if you have a manual. The awesome part is, the engine will keep going faster and faster until it kills itself. I suppose if you are feeling brave and you are really quick, you could somehow block the air intake with a balled up shirt or something.
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Nov 18, 2009 00:26
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Couldn't you just get under the car and drain the oil?
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Nov 18, 2009 00:30
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orange lime posted:Couldn't you just get under the car and drain the oil? I suppose you could, but you'd need to have tools with you and also be willing to get under an engine that is about to grenade itself...
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Nov 18, 2009 00:31
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With a Diesel you have to remember that they dont have an intake butterfly ( Well, VW's do for cold starting and shutoff) You control the motor by ritchening or leaning the motor. If you have a turbo with a blown seal it will just keep on pumping "Fuel" into the motor. Only way to stop it is to get the intake off and physically strangle the motor. Ive heard that sometimes you cant even stall the suckers ( Cluch just starts slipping) So you just give up and let it pop.
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Nov 18, 2009 00:33
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Reminds me of a story my dad told me. When he was at a automotive tech school in the 80's there was a runaway Cat diesel on a test stand. The instructor tried to stop it by putting a phone book on the intake. It sucked it in page by page. Apparently diesels will run on burnt phone books too!
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Nov 18, 2009 01:02
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Seems like you'd be able to stop it with something as simple as a small cannister of c02
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Nov 18, 2009 01:25
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UserNotFound posted:Seems like you'd be able to stop it with something as simple as a small cannister of c02 A fire extinguisher aimed straight at the intake, maybe?
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Nov 18, 2009 01:28
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KelvereseAysen posted:A fire extinguisher aimed straight at the intake, maybe? I bet you could install one of those tiny 9oz paintball cans to the intake triggered by a simple sensor/logic device. Is the ingnition switched off? Is the crank sensor indicating >3,000 rpm? YES. YES. FIRE THE THE C02!!
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Nov 18, 2009 01:37
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UserNotFound posted:I bet you could install one of those tiny 9oz paintball cans to the intake triggered by a simple sensor/logic device. I wouldn't trust one of those to not blow the burst-disk in that heated environment. I've had all of them, from 3.5 to 24oz canister blow burst disks simply by sitting out in the sun on a summer day.
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Nov 18, 2009 01:40
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KelvereseAysen posted:I wouldn't trust one of those to not blow the burst-disk in that heated environment. I've had all of them, from 3.5 to 24oz canister blow burst disks simply by sitting out in the sun on a summer day. Well if a manufacturer were going to engineer it in as a safety feature, I'm sure they'd have a better solution than a spare paintball tank  I kinda want to do an experiment now, though... but I think some more research is in order!
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Nov 18, 2009 01:48
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Stormangel posted:phone book on the intake. It sucked it in page by page. Apparently diesels will run on burnt phone books too! That is the fuckin poo poo!! I recall when I was doing my apprenticeship course, many moons ago my instructor saying the same thing about diesels continuing to run. He said try a small piece of metal or wood, say a short chunk of 2X4 over the air intake.
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Nov 18, 2009 01:51
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UserNotFound posted:Well if a manufacturer were going to engineer it in as a safety feature, I'm sure they'd have a better solution than a spare paintball tank Yea, but Brain... Where are we going to find a spare 6BT?
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Nov 18, 2009 01:58
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KelvereseAysen posted:Yea, but Brain... Where are we going to find a spare 6BT? It's all a question of MAF. It should scale reasonably well to any engine and any MAF. Things like unexpected friction due to heat and momentum due to the mass of moving parts are going to be why you just use way more C02 than even a scaled test indicates would be sufficient.
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Nov 18, 2009 02:07
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Forgive my noob question but, even overfilled, how does the oil get into the cylinder? I thought the cylinder had to be sealed, because it creates a vacuum on the downstroke to suck in oxygen and fuel for the compression stroke. I get that overfilling the oil could cause the engine to agitate and foam the oil, which is bad, I just don't see how it winds up pouring into the intake.
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Nov 18, 2009 02:20
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99% of diesels these days feed their Positive Crankcase Ventilation back into the intake manifold. So if you overfill them they will happily run on their crank oil. Holden had an issue with their 3.0TD motor in the jackaroos in australia with the Cat HEUI injectors- they were leaking and thinning out the engine oil with diesel, eventually getting it so thin it would go straight past the turbo seals and destroying the motor. My grandfather used to be a diesel mechanic, and had two run-aways on the test bed. One was a big Cat from a grader which started to eat its own oil- they threw a pair of overalls over the air intake (balled up) and it ate them. They just ran out of the shed and listened as it threw a few legs out of the bed. The second one was when the fuel pumps govenor broke on a big Komutsu diesel, and that thing went off its tits. Engine normally governed to 2300rpm revving at 6000+. Fixed that one by taking to the fuel pipes with a fire axe and severing them from the pump!
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Nov 18, 2009 02:28
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Leperflesh posted:Forgive my noob question but, even overfilled, how does the oil get into the cylinder? I thought the cylinder had to be sealed, because it creates a vacuum on the downstroke to suck in oxygen and fuel for the compression stroke. I get that overfilling the oil could cause the engine to agitate and foam the oil, which is bad, I just don't see how it winds up pouring into the intake. I don't know anything about diesels. On my ranger though, the 3.0L V6, there is a tube that goes from the crankcase to the air intake. It's so the engine can vent expansion gasses back into itself, and not the general atmosphere. It also ensure that any gasses sucked in are filtered as the tube is after the air filter. It's called a crankcase breather tube, or somesuch. If the diesel has a similar setup, then seriously overfilling the engine can VERY easily allow oil to be intermixed with the air going in. This picture is from a Taurus, but it's still a 3.0 V6. (Not diesel.) http://www.taurusclub.com/encyclopedia/Engine/Large/04_Vulcan.jpg Right above the oil-filler cap, you can see the breather tube. It goes from the crankcase, and up to the intake line.
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Nov 18, 2009 02:29
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So, if you wanted to engineer and build in a safety system to prevent this runaway condition, all you need is a device which severs that line when RPMs are reading high but the ignition is turned off? Doesn't seem that difficult to do.
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Nov 18, 2009 02:44
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Assuming that it is not running on its own oil from a leaky turbo or another source, yes.
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Nov 18, 2009 02:49
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tzam posted:Assuming that it is not running on its own oil from a leaky turbo or another source, yes. The Co2 purge seems like a cool idea. You would need enough to continuously blast the intake until the crank stops spinning on its own. Otherwise it would just start right back up again once the canister runs out.
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Nov 18, 2009 03:04
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alot of modern diesels have an electronic butterfly in the inlet to stop pumping loss. These can be shut to stop run away. I've seen photos of butterflies bent out and eaten, just to due to pressure differential and flow.
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Nov 18, 2009 03:38
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I remember, from my unfortunate time as a lube tech, the old Mercedes-Benz diesel engines had a small lever next to the intake manifold that had "STOP" printed on it. I can't find a picture, but I'm sure someone here knows what I'm talking about.Sockington posted:The PCV has to be changed you say? (250k MX6 V6)
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Nov 18, 2009 03:47
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UserNotFound posted:I bet you could install one of those tiny 9oz paintball cans to the intake triggered by a simple sensor/logic device. That is an awesome idea, due in no small part to it reminding me of a nuclear reactor's SCRAM system. In that case it's generally a big electromagnet holding a secondary set of control rods above the reactor, so if something goes wrong the magnet dies and the rods drop in and instantly shut down the reaction. Fun fact: the original emergency arrest system in the 1930s research reactors was very similar, but the rods were held up with a rope and pulley and they just kept a man on station with an axe to cut the rope. Fun job.
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Nov 18, 2009 03:58
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GWBBQ posted:I remember, from my unfortunate time as a lube tech, the old Mercedes-Benz diesel engines had a small lever next to the intake manifold that had "STOP" printed on it. I can't find a picture, but I'm sure someone here knows what I'm talking about. Former lube tech checking in to corroborate.
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Nov 18, 2009 04:05
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Ungry Ungry 6-71T's! The best and easiest is to cover the intake with a stop sign. Diesels when running away will eat anything. Shop manuals, rags, coveralls, small children, and the souls of the damned. I'd love to see a diesel poo poo a phone book out the stack followed by a set of coveralls.
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Nov 18, 2009 04:07
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KelvereseAysen posted:I think choking the engine would be the best way to combat runaway. No matter how you get your fuel, be it crankcase breather or hosed turbo, it doesn't combust without air. This is actually a pretty common option on heavy duty trucks. Any truck that does oil-field or refinery duty is set up with a guillotine cut-off right after the turbo on the intake side. Sometimes there are enough hydrocarbons free in the air on an oil field or refinery that the trucks will just run on what is in the air. If that starts to happen the driver has to just hit a switch and an air-operated plate pops into place and cuts off all air to the engine. I'm still looking for pics, I can't seem to find one right now... http://www.chalwyn.co.uk/EN/auto_shut_down_systems.html Good article, but "pics omittied": http://findarticles.com/p/articles/mi_m0FZX/is_9_73/ai_n27395070/ RandyF fucked around with this message at 04:20 on Nov 18, 2009 |
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Nov 18, 2009 04:15
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http://www.youtube.com/watch?v=-_EXtBEaBbs I apologize for the horrible horrible History channel treatment. But...one wing? come on.
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Nov 18, 2009 05:01
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sndgeek posted:http://www.youtube.com/watch?v=-_EXtBEaBbs I remember watching this some weeks ago. My reaction now is the same as it was then. 
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Nov 18, 2009 05:05
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sndgeek posted:http://www.youtube.com/watch?v=-_EXtBEaBbs Jet fighters are more of a missle with big wings than an airplane, its not so impressive that it flys with only 1 wing. Try that in a cessna, and see how well that works out.
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Nov 18, 2009 05:24
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hippynerd posted:Jet fighters are more of a missle with big wings than an airplane, its not so impressive that it flys with only 1 wing. Try that in a cessna, and see how well that works out. Take a fin off a missile and see how well that works out.
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Nov 18, 2009 05:36
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Godholio posted:Take a fin off a missile and see how well that works out. In that case, you adjust the controls to get it to hit its target. With a rocket (no guidance), they usually spin, but still generally go in the right direction.
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Nov 18, 2009 05:43
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Stormangel posted:Apparently diesels will run on burnt phone books too! Let's see, page 34 "Fuel mixing guidelines": "For usage of discarded phone books, mix 6 parts paper with 2 parts used engine oil, 1 part paraffin, 1 part coal dust. Set fuel quality lever to 4. Allow engine to suck in loose sheets as needed." 
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Nov 18, 2009 11:02
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KozmoNaut posted:Let's see, page 34 "Fuel mixing guidelines": Sounds like a B-52 flight manual.
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Nov 18, 2009 13:52
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I do recall an EMERGENCY marked lever in the cab of the 5-ton I drove in 2004. It was attached to a cable that pulled a lever somewhere on the left side of the engine, probably a fuel cut.
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Nov 18, 2009 15:34
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GWBBQ posted:I remember, from my unfortunate time as a lube tech, the old Mercedes-Benz diesel engines had a small lever next to the intake manifold that had "STOP" printed on it. I can't find a picture, but I'm sure someone here knows what I'm talking about. JointHorse fucked around with this message at 16:11 on Nov 18, 2009 |
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Nov 18, 2009 16:02
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hippynerd posted:In that case, you adjust the controls to get it to hit its target. With a rocket (no guidance), they usually spin, but still generally go in the right direction. If by "adjust the controls" you mean "reprogram the flight guidance system" then yeah. Rockets are designed to fly along a specific path...missiles are designed to steer and maneuver. That makes a big difference. It's all computer controlled, and the computer is programmed for the missile to fly a certain way. Remove a fin and that changes dramatically. And the computer isn't programmed to handle that kind of change. Same thing with the F-15. Every modern fighter is inherently unstable. This improves maneuverability significantly. But it means the pilot's input doesn't directly affect the flight surfaces...the computer receives the input, decides how best to make it happen, and actually makes the adjustments. The computer was not designed to fly with one wing. McDonnell Douglas ran multiple simulations and were absolutely stunned the plane landed safely.
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Nov 18, 2009 16:08
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The programming in FBW computers is fairly robust. The Hunter UAV is totally FBW, or rather, it can fly itself, but accepts directions from humans. We landed one with no left aileron in '04. The pilots didn't even notice a difference.
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Nov 18, 2009 16:24
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hippynerd posted:Jet fighters are more of a missle with big wings than an airplane, its not so impressive that it flys with only 1 wing. Try that in a cessna, and see how well that works out. Man, I've lost several days trying to fly that loving Dodo.
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Nov 18, 2009 16:40
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Sorry for the doublepost, but there's a distinct lack of pictures on this page, so I thought I should at least contribute something. "Hmm, so none of the gears work, but there no extra noise or anything from the engine or the gearbox? Ok we'll come and and pick it up, and we'll look what we can find out. It shouldn't be anything serious.." Differential in a Peugeot 405 decided to grenade itself.
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Nov 18, 2009 16:47
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