runaway diesel

i know that to shut a runaway diesel down you can block the air intake or possibly shut the fuel or use co2 but I was just wondering if blocking the exhaust would work as another option since it is sometimes difficult to get to the air intake and fuel on some engines.

any thoughts?

thanks

Exhaust gases pressures are extremely high, thats why turbos are so effective. I doubt that you could effectively block it to shut down an engine.

deisel engines operated in hazardous locations such as oil field work must have a rig saver installed. this is a an air shut of valve that is installed in the intake and when you hit a switch it will positivly shut down the engine right now.prevents further gases from atmosphere entering the engine. shutting off the fuel as you say will do nothing,it will keep speeding up till it blows up. the answer is to eliminate any fuel entering the intake.

also good to have a plan of attack if your in this situation without a rig saver. keep a piece of small plywood or jacket or something you can throw over the intake to cut the intake air off.

We had a Lister diesel on a generator that wouldn't shutdown. When we blocked off the fuel it started using the crankcase oil. Covering the intake air stopped it. We replaced it with an Onan. Hal

Exhaust brakes block off the exhaust pipe and slow the engine but it will keep on running.

And never use your hand, especially if you have the turbo open to work on the engine!!
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Any piece of flat wood wider than the opening will shut it down.

If you are messing with the pump when it hits run-away, the shut-off will not cut the fuel, the only way to stop it will be to cut off the air.

I always kept a small piece of an old clip board on my tool box to throw over the intake.

No fuel used on everyday engines will burn without air/oxygen.

Bad thing with newer computer controlled engines once they over rev the computer senses this and locks out the controls to put a load on the engine to help slow it down or kill it.

You have that backwards! When you limit the air is when it starts running on oil-that is why they have the rules they do in turbo tractor pulling!

Has anyone tried to use a Jake Brake on an engine running at full power? Is there a pressure relief valve that limits the maximum back pressure?

When you restrict the intake air you only have to hold back 15 PSI of atmospheric air from entering the intake.

A diesel's compression pressure is around 300PSI? To completely stop a diesel engine running at full power by restricting the exhaust you would need to hold back maybe 300 PSI to 700 PSI of exhaust pressure. Odds are you would blow out some gaskets or split the exhaust system somewhere before too long. Exhaust manifolds would have to be fastened on like a cylinder head to prevent them from being blown off the engine. It might be made to work with a lot of effort, but it would not be nearly as inexpensive, light weight or reliable as restricting the intake.

Had a Detroit on the next engine stand over run away when I was in trade school back in the late 1970's.
Threw a three ring binder on the intake of the supercharger. Dang near sucked the plastic cover off the binder! Man those old hondas scream when the run away!!!

decompressor bar on 800 case and other models prevents that ,, yanmar 2222 has this feature too ,..they cant run away when you flip the valves open , CAN THEY ?

You mean like this?

thank you for all the info. sounds like blocking the exhaust will be very difficult if not impossible to stop a runaway.

Two stroke Detroits have an emergency shutdown on them. A flap covers the blower intake when activated, usually by a cable to trip the spring loaded flap. This sometimes results in damage to the blower, but saves the engine.

No, they have air shut off on diesels for pulling to stop runaways. Like was said earlier when you have uncontrolled fuel, the only way to stop one running on uncontrolled fuel is block the air supply. Any organization that doesn"t require an air shutoff on a modified diesel is just plain stupid.

One detail I see everyone forgot, even those that mentioned the shutdown flap on a two stroke Detroits air intake. That details is that Detroit can runaway backwards. When running backwards the blower is then sucking air in the exhaust and pushing it out the intake side. Due to the air flow beign reversed it creates a vacuum -vs- a pressire in the air galley around the pistons. Because of that vacuum it can very easily suck engine oil past the oil control rings causing it to run on the engine oil instead of fuel, and run away. Dad choked one down on an elevating scraper years ago while doing a pressure check on the hydraulics controlling the elevating blades. Due to hydraulic pressure in the system when the engine choked the reverse pressure on the pump caused the engine to kick over backwards and it fired back off running backwards. Dad said it was the messiest, smokiest thing he had ever seen. I think he said he stuffed a handfull of rags down the muffler to restrict the flow of air and get it to shut back off.

Long story, but the point is that you just might have to block the "exhaust" at some point to shut down a Detroit cause the flap on the intake isn't going to do anything but pop out of the way under pressure.

Sure if the machine is half apart and the blower rotors or the turbo inlet is exposed.
Had a DD run away and choked it down with just the palm of my hand over the inlet stack.

If you are referring to the jacobs type exhaust valve, they work by keeping the exhaust valves from closing so that there is no compression to ignite the small amount of fuel still coming through. Think about it.. Why is there more noise coming out the pipe when the Jake is on.