Runaway diesel engines ????

[kebo]

I was watching a youtube video last night on runaway diesel engines and not being much of a mechanic was wondering what the most common cause was for that condition?? I'm guessing it's usually a malfunction with the injector pump? I know the best way to shut down a runaway diesel is to block off the air intake flow (actually a mechanic did just that in one part of the video) , but not all engines are set up so that you can easily do that. I guess it mostly has to do with the design of the air filter and how easily you can block it. Hopefully, that's something I'll never have to deal with!

 

[jaotguy]

VW diesels when they get older tend to have excessive blow by ( oil vapour ) same as injecting fuel into cylinder ....

governors can malfunction ...

turbo seals can fail on the intake side

diesels will burn any oil as long as they have compression and air....

 

[stuckmotor]

In the list of similar threads below, the top one is interesting and informative. I'll try to put in a link but, doubt it will be clickable.
http://www.tractorbynet.com/forums/owning-operating/290526-type-abc-fire-extinguisher-any.html

 

[Soundguy]

yep.. drinking their own fluids.. and natural gas / propane leaks...

choke plate or some other way to suffocate them.

I think I'd strip outta a shirt or jeans and stuff them into the air filter housing before letting my 24k$ machine wind out...

 

[puckgrinder85]

They'll run on anything they can like said, ruptured gas lines from digging in the wrong spot come to mind. That's a really bad thing to happen. But yea, anything flammable going into the engine can fuel it, even when you shut off the engines fuel supply.

 

[skyhook]

Had it happen to me, two years ago, on a 1993 Ford F250, 7.3 diesel engine.
Scary stuff, a spring in the injection pump let loose somehow,
the engine revved full rpm's, white smoke everywhere,
took the air breather off and tried to kill the air going into the intake,
but there was a nut in the center that held the breather, stopping me from
completely shutting all air supply.
It slowed the revs down while I held my hands over the intake,( had leather work gloves on) but it wouldn't die.
I couldn't take my hands off or it would rev back up
Yelled at the neighbor to go get a crescent wrench and he disconnected the fuel line,
it finally stopped.
If you can't stop the air intake or whatever is feeding it, stand back, when these things blow,
it ain't funny.
Never use your bare hands to stop the intake flow, it'll suck your fingers in.
Overfilling of oil can cause this also, it runs on the crankcase oil until theres no more.
Once it's started, there's no stopping it, unless you kill the feed it's thriving on.
Never want to see that again.

 

[TnAndy]

Overfilling of oil can cause this also, it runs on the crankcase oil until theres no more.

Yep....that was my first experience with runaway diesel. Small 8hp Lombardini diesel on a tiller. Changed oil in the fall before I put it up, and didn't check it on spring startup. I suspect fuel seeped thru the injector pump into the crankcase and had the level over full. Started it up, got about 30' down the driveway and it took off like a chainsaw engine. Had NO idea a diesel could do that kind of RPM !! And didn't know what was going on to stop it. It finally ran out of excess crankcase fluid and stopped ( I'd already jerked the fuel line loose ).

Amazingly, no damage, still running today. But you can bet I check the oil level EVERY time now before I start it !

 

[Mechanos]

A CO2 fie extinguisher aimed at the intake can starve the engine of oxygen and stop a run away engine. This wo4ks well if the intake is hard to get to.

 

[Raised on a Deere]

Cleaned the wire mesh on a oil bath filter on a John Deere 2020 when I was young. Reinstalled the filter with a fresh batch of oil. Started the engine and the gasoline in the wiremesh sent the RPMs momentarily through the roof. Somehow the engine did not blow. It was an unforgettable experience. You can't imagine how fast one of these engines can turn on the path to destruction. You have to see it to believe it.

 

[Bwgad96]

A CO2 fie extinguisher aimed at the intake can starve the engine of oxygen and stop a run away engine. This wo4ks well if the intake is hard to get to.

This is a trick I was taught by the fire dept.