Diesel Runaway Engine

Sounds good, just eliminate the air or fuel, but its not always that easy. Most runaways happen during service, or soon after. Stationary equipment is really prone to this failure. We had one happen in the shop, new truck being setup for delivery. Tech had set the idle too high, and instead of shutting it off, tried to change the idle speed on the injector pump, but with it running, there was too much pressure on the idle adjustment to move it. Kept running faster and faster, turning the key off did nothing, used every extinguisher in the shop, only slowed it momentarily, white smoke was filling the shop. Finally someone pulled off the air cleaner pipe, and placed piece of sheet metal over it. It almost stopped, but back-fired blowing the sheet metal off, and resumed the runaway. Finally stopped it by placing a 1/4" plate on the intake stack, and put a #100 sack of sand on top. We could not hear anything after the fact, and was very hard to find the roll-up doors to open, to get the smoke out.

Broke both heads and other assorted items, remember this is a NEW truck and the customer wanted the truck to work. It was almost 2 weeks to fix and get it out the door. A runaway diesel I not joke, especially if it is a large stationary that normally runs at 800 rpm max, and starts turning 2 grand, and nobody will go near it.

Busskipper wrote:

carringb wrote:

Busskipper wrote:

Rollnhome wrote:
Wasn't exactly sure where to post this, but this is what happens and what a runaway diesel is. I'm sure you'll get the idea. Runaway Engine

Eliminate the air - it will stop.

Or eliminate the fuel - it will stop.

Help?

Yes and no!

Runaways are usually caused by a busted turbo oil seal, and the oil becomes the fuel. That's why those events are so smokey. Cutting the fuel does nothing, and neither does cutting power. Cutting air is the only way to stop it, but there's no way I'd want to put myself next to an engine that could spit a piston and any moment. Plus, the damage from overspeed is most likely already done.

That might be why cutting the air is the first choice.

Only had it happen twice on a detroit - once just the flapper and once we cut the fuel.

But you are correct - it would be my guess that the video is of an engine running on the oil in the engine - and likely it is already just scrap.

But very rare,

Thanks for the explanation. I guess that's why the smoke was greyish.... mixing with antifreeze as it was burning the oil, etc.

MM.

carringb wrote:

Busskipper wrote:

Rollnhome wrote:
Wasn't exactly sure where to post this, but this is what happens and what a runaway diesel is. I'm sure you'll get the idea. Runaway Engine

Eliminate the air - it will stop.

Or eliminate the fuel - it will stop.

Help?

Yes and no!

Runaways are usually caused by a busted turbo oil seal, and the oil becomes the fuel. That's why those events are so smokey. Cutting the fuel does nothing, and neither does cutting power. Cutting air is the only way to stop it, but there's no way I'd want to put myself next to an engine that could spit a piston and any moment. Plus, the damage from overspeed is most likely already done.

That might be why cutting the air is the first choice.

Only had it happen twice on a detroit - once just the flapper and once we cut the fuel.

But you are correct - it would be my guess that the video is of an engine running on the oil in the engine - and likely it is already just scrap.

But very rare,

The mulit-fuel M35A1s, that I worked on, while in the Army, were famous for runaway. I carried tools on the wrecker to cut the fuel lines. In the M35A1's case, it was fuel pump failure.

Richard

I drove Peterbuilts with diesel engines for 44-1/4 and never had this happen, and never heard of this happening until now! Must be very rare.

Rollnhome, I definitely found the video interesting. Just wondering how that can happen and how we can turn our engine off if the key does not.

We have an emergency fire suppression system that sprays the engine. Maybe that would help more 'after-the-fact'?

MM.

Putting it in gear and popping the clutch may have saved the engine but wrecked the transmission and/or drive shaft.

Busskipper wrote:

Rollnhome wrote:
Wasn't exactly sure where to post this, but this is what happens and what a runaway diesel is. I'm sure you'll get the idea. Runaway Engine

Eliminate the air - it will stop.

Or eliminate the fuel - it will stop.

Help?

Yes and no!

Runaways are usually caused by a busted turbo oil seal, and the oil becomes the fuel. That's why those events are so smokey. Cutting the fuel does nothing, and neither does cutting power. Cutting air is the only way to stop it, but there's no way I'd want to put myself next to an engine that could spit a piston and any moment. Plus, the damage from overspeed is most likely already done.

I'm not jumping up into the rig or under the hood to cut off fuel or air. Let'er run, it will shut down eventually. :)
Just thought some would find the video interesting.

That used to be an issue on Detroit 2 strokes and there was an emergency kill knob that dropped a flapper over the air intake.

Never heard of one on a modern 4 stroke diesel. I suspect if my Cat 12L ran away it would merely self destruct and end the problem.

I sincerely doubt this is an issue that requires any expenditure of energy.