Runaway diesel

[itbrokeagain]

What makes a diesel run away?

[Flxratd]

assuming your asking why it would not shut off ? or do i need to come up with a punch line like somebody kicked it in its truck nuts...

[93 Krawler]

That's a trick question. It can't run away, it doesn't have legs.

[fastford]

Need more info.... What kind of vehicle is it in? Electronic or mechanical fuel system?

[GPER]

We had a Volvo 35 ton 6x6 end dump with a new dealer rebuilt motor take off. We removed the air filter and stuffed coats into the air intake. It was hard on the turbo, but it slowed the motor enough along with a strain from the hydraulic system to kill the motor. I think it turned out to be something in the fuel pump.

[itbrokeagain]

Originally Posted by GPER

We had a Volvo 35 ton 6x6 end dump with a new dealer rebuilt motor take off. We removed the air filter and stuffed coats into the air intake. It was hard on the turbo, but it slowed the motor enough along with a strain from the hydraulic system to kill the motor. I think it turned out to be something in the fuel pump.

Yes. Something like this. Where it wont shut down and wont idle down. No trick question this time

[94Dodge Truggy]

Had a friends military truck do this. We had a propane leak once and an injector pump failure another time. RPM's can get up to where the motor will scatter and big parts become projectiles. Putting a shop rag in the intake was useless but neat to see as the exhaust from the truck was omitting a red haze. A piece of sheet metal stopped it the first time. That poor poor motor!

Another time a plumbing company hit a natural gas line with a back hoe and it made the back hoe really fast! It had twice the power!

[Trigger]

What's really weird is to see one run backwards and have the intake and exhaust reversed.

[dodgetech77]

over-revving the engine can cause it, i think it is most common with the 2stroke diesels, but im pretty sure it can happen to most if not all. basicaly the motor has no butterfly to shut down air to the motor, (like a gas engine), and since it doesnt need spark, there is no way to stop the ignition of fuel.. once it reaches a certain RPM, it pulls combustible fluids from wherever it can. ive heard of turbo seals blowing, and motor running on its own oil, and also i believe the motor if revving fast enough can suck oil through the valve seals, etc... (maybe even pull fuel through weak injectors?)
I talked to a guy that over revved a brand new rebuild because on iniitial startup its sucked a bunch of oil out of the intercooler that had apparently been deposited there when it originally blew up. Apparently its pretty easy to do if you are not careful....

[twiztedzuki]

Originally Posted by 94Dodge Truggy

Had a friends military truck do this. We had a propane leak once and an injector pump failure another time. RPM's can get up to where the motor will scatter and big parts become projectiles. Putting a shop rag in the intake was useless but neat to see as the exhaust from the truck was omitting a red haze. A piece of sheet metal stopped it the first time. That poor poor motor!

Another time a plumbing company hit a natural gas line with a back hoe and it made the back hoe really fast! It had twice the power!

yeah ive seen excavators hit propane line and takeoff

[fordman00]

What year make model etc

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[blazerbrad]

The main design feature that allow a diesel to do this is that no external spark source is required (i.e. spark plugs) to start combustion. Just keep dumping fuel in it and it will keep running, and older diesels will run on just about anything that will combust. Also no butterfly valve to control air flow, so just like you were holding the accelerator pedal to the floor on a gas engine. The injection pump, driven off the engine, can usually also keep pulling enough fuel regardless of if the lift pump does not work (i.e. if you had an electric fuel pump). Basically, no electric powered is required to run these.

With that said, it's unlikely to see this condition on a modern diesel engine with all of the electronic controls.

[itbrokeagain]

Originally Posted by fordman00

What year make model etc

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Nothing specific. Was using a backhoe today and was thinking about that.

[timido]

I heard tales of a one of our Buses running away. It had a turbo gone very bad and the guy working on it did not drain the oil from the Charge cooler. There was enough oil that it ran away when he started it with it repaired. I had one that needed a turbo. I drained the charge cooler and got 4 Gallons of Oil out of it. I am guessing that could be enough oil to do it

[Coppertop]

A co-worker with a cummins engine blew the oil seals in the turbo charger,leaking enough engine oil into the intake causing the engine to run away.

No legs needed...

[drmeece]

This thread reminded me of this.

http://youtu.be/WrAeUf7v49g