Runaway Diesel?

[Shadow5501]

Originally Posted by Rob_M

That won’t stop a runaway diesel. Only way to do it is seal the intake inlet and no one would ever have time to do that on a DP.

Runaways rarely happen and almost always were after a rebuild, or new engine if the pump or governor wasn’t assembled correctly. more common on old mechanical injected diesels. Engine dyno operators would be prepared with paddles with gasket material glued to one side to cover the turbo inlet. Even then if ring seal was bad enough it would burn its own engine oil and destroy itself.

My dad had this exact scenario occur on his sailboat in the 1980s. It was a 50ish HP Perkins diesel IIRC. Ran away when started in the harbor thankfully. It took a while to shut it down because the engine was covered by the stairs to access the cabin. The oil rings were gone and the crankcase was full of fuel. It was ugly. It got replaced with a more modern diesel from Yanmar.

[jacwjames]

I saw this one time on an underground mine locomotive, I think it was a Cat engine. From memory it was the old style injector pump lubed by engine oil. Oil seal failed and put engine oil into the engine. The engine took off and ran high RPM, black smoke billowing from the exhaust. Diesel foreman was there and had enough sense to pull the air intake and put a rag in it.

This type of issue in an underground mine is a worse case scenario. Never good.

[Kjon]

I was was just thinking of my dad. If I recall correctly my father occasionally drove a Mack B61 diesel. As a young man I would sometimes accompany him mostly delivering to Bethlehem Steel at Sparrow Point, MD. There was a knob on the dash that he pulled to stop the engine. He told me it must stay pulled or the truck might start with all the problems implied. With modern technology controlling the fuel delivery process and assuming a technology failure fail safe shuts down the engine, I'm guessing a runaway is no longer a viable problem. At any rate I have not heard of one.

[Isaac-1]

All that modern technology does nothing to stop it if the source of the oil/fuel is the oil feed to the turbo bearing.

[imUrlaub]

I'm no diesel mechanic! I'm a tax accountant and Enrolled Agent so if anyone has a tax law question I'm up for it.

That out of the way...what about plugging the exhaust? Easy to access. My friends told stories about plugging the exhaust with a potato that seemed to do the trick. Big potato? Am I being naive here? Anyway, if anyone has a tax question I'm your guy.

[wolfe10]

Can it happen-- SURE.


If there is an "alternate fuel source" not controlled by the engine controls it WILL happen.


But, on modern 4 stroke engines, so rare it is a NON-ISSUE.


Yup, if your diesel is burning a quart of oil every 25 miles, it may happen. But unless you are paying absolutely no attention, run-away will sure not be your first symptom.

[Piros1]

This use to be a common problem with the early Detroit Diesel engines that had a roots style super charger. They had two shut downs on them. One was for normal use and one that was an emergency shut down that when pulled it would shut the intake air off from the engine preventing what is know as a run away engine. Look it up online. Rarely will you see this happen to modern Diesel engines that are turbocharged. To much to explain here but if you look it up online you will get a better understanding of it b

[Clemson]

If your engine was made in the last decade and a half, you really shouldn’t worry about run away Diesel engines….

[W5CI]

Unless you have a very old coach with the 2 cycle Detroit engine dont worry about a runaway. it wont happen to a modern diesel engine that is computer controlled

[Skokkian]

I had this twice on my sailboat. What happened was that the lift pump failed and was filling the sump with fuel. Had the injector pump reconditioned and it happened again! Lift pump was last option!!

Unlikely to happen on modern day common rail diesels with electronic injectors.

[twinboat]

Originally Posted by imUrlaub

I'm no diesel mechanic! I'm a tax accountant and Enrolled Agent so if anyone has a tax law question I'm up for it.



That out of the way...what about plugging the exhaust? Easy to access. My friends told stories about plugging the exhaust with a potato that seemed to do the trick. Big potato? Am I being naive here? Anyway, if anyone has a tax question I'm your guy.

The engine is running over full throttle and the exhaust will be burning hot.

Your potato will bake just getting it near the pipe.

The potato thing is to stop an engine from starting, and I'm not sure that will work either.

[harleyjt]

Originally Posted by TiffinUser

This can happen with a gas engine also. Believe it or not, it is called "dieseling". It's happened to me off and on over the years with carburetor engines. Fortunately, it was always on a stick shift so I would kill it by popping the clutch in a high gear. A proper tune up fixed the issue.

Trust me. A gas engine dieseling is nothing like a runaway diesel. A runaway diesel will generally over rev and throw parts. I used to have a picture of a clutch disk that went through the floor pan and into the bottom of the dash and into the HVAC box.
jt

[Florida Rang]

In 1984 I was working on a Detroit 6-71 engine when it started to run away, all mechanics in that shop allways had a telephone book on thier workbench. So I grabbed the telephone book and put it over the air intake it took a while for engine to stop but it finally did. It was a real unnerving experience being that close to an engine running wide open and then some. I have never forgot that it.

[ka5gyo]

Runaway diesel is usually the cause of refinery or gas plant explosions. Gaseous atmosphere, goes into intake of diesel generator, welding machine, vehicle,. Runaway occurs, engine self-destructs, ignition, plant blows up. You can stop by stuffing a blanket, rags or coat over air intake. Not apt to happen on any vacation most might take in the MH. I would find something else to worry about.