Runaway diesel??? holy crap that's a lot of smoke!

So I'm driving down the highway yesterday, approaching downtown St Pete when I notice that there's so much smoke up ahead that I literally have to slow down to idle speed because there was so no visibility. I might have been able to see like 3 or 4 feet in front of my truck, if that.

So I'm thinking "holy ****, is the whole block on fire???", until the smoke begins to clear and the picture comes into focus. All of this smoke is billowing out of the smokestacks of a dumptruck that is parked on the side of the highway. Think of how much smoke comes out of one of those big turbo diesel tractors at a tractor pull, and multiply that by like..a hundred. It was unbelievable. I have never seen that much exhaust before in my life.

In addition to the smoke show, there's no one in the truck, the fire dept is there, and the cops have formed a perimeter around the truck.

Could this have been the phenomenon known as the "runaway diesel"? I've heard crazy stories from diesel mechanics about runaways in big trucks before.

Anyone ever experience this? Why can't they just cut off the fuel when this happens???

 

A runaway will usually only run for a couple seconds before catastrofic engine damage happens. But I'm not sure what you saw.

 

I agree with crusty nut. MOst of the time the runaway diesel is with a 2 stroke Detroit diesel. the only way to shut it off is cut the fuel or air.

 

How else are you supposed to shut off a Diesel?

 

I would to prefer shut of the fuel.
I have tried the other one.

Result!
My hand got stuck in the intake.

 

If the turbo blows a seal the engine will run on the crankcase oil even if the fuel supply is shut off. It will go till the sump runs dry, or maybe a CO2 extinguisher in the air intake.

 

I've seen this happen one time. The technician put a pice of sheet metal over the inlet of the turbocharger and boom, near instant death. Well, not DEATH but it shut it off.

Smoke is caused by an excess of fuel. If you turn the fuel up, you'll get smoke. I remember seeing a video (on youtube maybe?) of a Kubota tractor that the owner turned the fuel up on. It smoked like a chimney at idle.

Although smoke looks cool, it's not wanted. Being able to make gobs of power WITHOUT smoke is much more impressive as it shows the builder's mastery of the air/fuel ratio.

 

Every Dieael mechanic knows that CO2 in the intake will kill it. The fire guys should know that, too.

The older GM Diesels (before turbos) used to have a flapper valve called the Emergency Stop, which closed off the intake air.

Frank

 

I seen a Detriot rap up to what seemed like 10 grand inside a shop- one of the scariest moments of my life.

 

There's not much that a co2 extinguisher in the intake won't stop. Maybe 2 for a top fueler, but you'd better just run away from a top fueler.

 

Poor you,

You never got to see the Phoenix push off from the starting line.

 

pictures or it didnt happen

 

oh just turn off the spark...wait a second

hey outlaw bender, how bad was the hickey on your hand after that?

 

what happened in that motor depends on the COLOR of the smoke... white is steam, blueish is oil and black is a blown turbo... lotta causes, different color smoke

 

Diesels do not have "spark", they use compression to ignite fuel, exactly like a 1978 oldsmobile would "diesel" and "run-on" after you shut it off.

A diesel does not have any sort of "****erfly" or "throttle" to control the ammount of air the engine ****s in,,, it ****s in all it wants. The rpm/power is controled by the ammount of fuel injected into the cylinder. The more fuel injected, the bigger the boom, the rpm's go up. That's why 18 wheelers can idle their trucks overnight and only use 3-4 gallons for a 10-16 litre engine. They are EXTREMELY efficent.

A diesel engine will run [quite well] on used motor oil. Infact, I'v done it myself.

So, if a diesel blows a turbo seal, and dumps a steady stream of motor oil into the intake stream, it will run un-controlably. There have even been instances where an older [loose] diesel engine has ****ed oil from around the valve seals and up around the rings and "run away".

It's entirely possible that's what you saw.

What's scary on a "big rig" that's run away on motor oil is that some of those commercial diesels will hold 12-16-even 20 gallons of motor oil, so it's possible for a diesel to run for a looooong time before it blows, or ****s the sump dry and locks up the bearings!!!

 

That's exactly what I was picturing as I read the story

 

I have had one of the trucks I was driving run away. It was a Cat 3406 B. That means 6 cylinder mechanical pump. The pump is designed so that the pedal controls the RPM limit by a centrifical govenor and the fuel delivery follows that limit. I had my govenor fall apart, while driving, therefore no limit on RPM. The truck took off like a bat out of hell and no stopping the motor. turned off the key, but too late the truck RPM's were so high that it was ****ing oil past the rings. Two choices, pop in neutral and let it blow apart or ride it out till it quits hopefully saving the motor. I got lucky, kept it in gear and had enough brakes and weight on the truck and was able to stall the motor, before it blew apart.


Scarry as ****, to be driving and loose throttle control. While driving down the road with 450 Hp, 1250ftlb of tourque without any controll at all except the steering wheel.

I also had another truck runn backwards for a bit, that was interetsing. Missed a shift wit the Jake Brake on, the motor almost stalled, then I pressed in the clutch and it ran backward for a bit. Turned off the key it stopped running, started it right back up, and off I went.

 

I've seen a diesel "runaway".....it was a Kenworth offroad semi with Detroit Diesel Silver 92, which was turbo'd AND blown.....the turbo FEEDS the blower...like on many Detroit powered off road equipment.
Those old Detroits could SCREAM......and it ran up there in the rpms before we got her killed using a rag into the intake once we knocked the boot off.....

 

man i would have liked to seen a pic of that, i do a lot of diesel work on the newer stuff i geuss wich its not common to have a run away.

 

Ha! Give it a few years. Sooner or later some sensor will malfunction, or computer program will go hay-wire, and these newer "E" diesels will suffer much worse than their mechanical predicessors. If nothing else, there's no electronic gizmo that will keep it from ****ing oil out of the sump, or from a blown turbo seal.

IMHO, give me a full mechanical oil burner ANY day over these new rolling computers.

 

My step-dad works for Tx-DOT and they had a detroit run- away in the service shop. He threw a service manual over the blower intake to kill the engine. Saved the engine, but trashed the blower

 

When I was 18 I washed a 2 cycle 671 detroit diesel's air filter box out with solvent and left some in the bottom. Holy ****, it ran wide open, I pulled the air shutoff completely off the dash and it ran WFO for about 2 minutes which seemed like a lifetime. Scared the **** out of me

 

I always heard that could happen, bet it sounds awful too. Guess the only choice if the key doesn't stop it is to plug the tailpipe to keep it from getting intake air.

 

A 2-stroke diesel would runaway when you run out of fuel with it. You had to shut off the air supply and they were equiped with a ****erfly valve in the intake system for that purpose. What you probably witnessed was a blown turbo. I had a 769 Cat truck do that and the smoke probably killed every bug in a 10 mile radius. .....Bob

 

Try having a 8-71 run away while you are laying on top of it setting the governor!!!

 

We had a truck come in that ran away. It was a newer computer controled engine. The turbo seals went out and it pumped oil into the intake. It took off and the driver abandon ship.... It ran at a very high rpm until it pumped the oil pan dry... It was a Cat warranty deal. The owner of the truck wasn't very happy when all Cat would do is install a new turbo on the engine and fill the oil. Far as I know the truck is still running. We have CO2 fire extinguishers in the shop that work good to bring engines down when they run away (not like it happens very often). Also had a 7.3 ford run away on oil. The mechanic put a new turbo on but never pulled the intake air cooler that was full of oil....
Jeff

 

Saw this or something like it recently, maybe on the way back from the Roundup. So much smoke you couldn't see and it was pouring out of the stacks on a dump truck.

 

I had a very old boat with a ford/Lehman 6 cyl diesel in it. Motoring back to harbor one day into the tide and wind I had the hydraulics fail in the gearbox and the motor ran away. It wound up tight (well, tight for that motor) and lasted 20 seconds or so until I could shut the fuel off. I was ****ting myself the whole time.

Last summer at the Vol. Fire Dept. I'm on we were teaching a new member how to operate the tanker. He managed to just about stall the motor before he pushed in the clutch (he didn't release the brakes), then he was baffled as to why he couldn't find a forward gear. A few moments into it and the engineer instructing him caught onto the problem.

Fun stuff.

 

I've only had a one lunger diesel run away I cant imagime an 8-71! managed to get a 6-71 to run backwards-couldn't figure out why there was smoke coming out of the air cleaner!

 

Wow.

Good stories.

Sorry I didn't get a pic, but it was a full traffic scene with no visibility. I was way more concerned with just getting through there in one piece and the whole taking-a-picture thing didn't even occur to me until I had p***ed it.

One of the weirdest things I've ever seen on the road.