Here is something I have never heard of in all my years of turning wrenches and fixing stuff.Got a call, (multiple texts actually) from a close cousin yesterday. They had just got back from a nice time away camping with their small 5th wheel. No problems, truck is like new, runs perfect etc. 196,000 K (122,000 miles) Smaller trailer, nothing for a CTD to pull. They got home fine, parked and went about their business.Next day her hubby started the truck up and in my cousins words, it blew up, filling the whole yard with white smoke, and the revs went up out of control. He shut the key off, but the engine kept running and racing, clouds of white smoke billowing out. Since it wouldn't shut off, he pulled it into drive and somehow managed to stall it out.Wow! Just wow! What the heck?She told me to Google search "Diesel Engine Runaway" I did, and read up on something I am totally unfamiliar with. What on earth could possibly be feeding unchecked fuel to the engine? Has anyone ever experienced this? Or know anything about it?Truck will be towed to a mechanic tomorrow for evaluation. The concern here is the obvious, engine damage, but further than that other driveline damage, especially the transmission after dropping it into drive to stall the engine. Sad, the tranny was new when they bought the truck about 3 years ago from an older man, the original owner.Any thoughts from my Cummins friends here or others?

Yep... bad fuel control so fuel continued to flow with key off...too much so as evidenced by white smoke. Marine, aviation, train engines, all have positive fuel shutoffs...auto/rv never required. Your only option is what he did to stall it, which could cause damage, OR pinch fuel line closed with vise grips, OR crack a filter... if you can get to it safely. Kind of dumb, but not a very common occurence, until it happens to you...then it's 100%, just like a lightning strike or shark bite.He may get lucky.

No.I had a throttle stick in the wide open position on a 1965 Corvette. That was a long time ago. I was on a windy road lined with trees. The steering wheel did not lock up in those days, so when I turned off the ignition, I still had control of the car.

Any turbo diesel engine can have a runaway...and it can be engine oil or fuel issues. The first one I saw was on a tractor and was said to caused by a cracked engine oil line with a huge amount of white smoke. The driver (tractor pull) calmly like he did it all the time placed what looked like a 10" X 10" piece of plywood over the air intake and killed the beast.

A few years ago there was a video of a UPS truck having a runaway. If you were on the highway when it happened I guess you would have to shift to neutral and let the engine fail.

Never happened to me, but known, and I’ve seen it happen to an 18 wheeler.While it can be due to fuel system malfunction, it is more commonly turbo bearing oil seal failure which feeds engine oil into the intake, and since diesels are oil burners, you have uncontrollable fueling. If the engine doesn’t almost immediately self destruct, you can minimize damage by finding a way to stall it. Either way, it is an expensive event.

Diesel Engine Runaway - 2005 Cummins | Good Sam Community

JRscooby
Explorer II
Aug 24, 2020
colliehauler wrote:
JRSCOOBY had a JD backhoe that started to have a runaway on a gasoline pipeline leak. With it just shut it off.

If you go to YouTube and type in runaway Diesel there are several videos.

Any compression fired engine will run on, if there is combustible vapor in the air. Lube oil leaking into the turbo from the the seal that is to keep it in the bearing is most common.
For that matter, when they first leaned out the fuel mixture on spark plug engines they had issues with them continue to run when shut off. First solution was let the air flow shut off tighter when shut off ignition.
Old-Biscuit
Explorer III
Aug 24, 2020
colliehauler wrote:
Old-Biscuit wrote:
Back in the 60's/70's diesel engines were prime driver for on-site generators for power on oil drilling rigs
Run aways WAS an issue and choking off AIR supply was the most common method of getting them shutdown

Engines were typically toast due to overheating and lack of lubrication from the HIGH RPM

And being up in the derrick when it happened was intense!
How do you have any hearing left? Those old screaming jimmie's were incredibly loud.

That is because the 'monkeyboard' was 90' above drill floor...
dodge_guy
Explorer II
Aug 24, 2020
if the injectors stick open it will do just that. I have seen a couple of injectors at the beginning stages of failure on that particular year Cummins. if you revved it, it would continue to rev for about 5 seconds and then settle back down slowly. the injectors I believe got weak from the tune that was in it. I found 3 bad injectors, but recommended all 6. That fixed the truck. Not sure if that`s the same issue here.
noteven
Explorer III
Aug 24, 2020
You need positive air shut off to stop a diesel engine in runaway.

Example: Roda Deaco

All diesels come with a fuel shut off that is how you stop the engine in normal operation.
colliehauler
Explorer III
Aug 24, 2020
JRSCOOBY had a JD backhoe that started to have a runaway on a gasoline pipeline leak. With it just shut it off.

If you go to YouTube and type in runaway Diesel there are several videos.
colliehauler
Explorer III
Aug 24, 2020
Old-Biscuit wrote:
Back in the 60's/70's diesel engines were prime driver for on-site generators for power on oil drilling rigs
Run aways WAS an issue and choking off AIR supply was the most common method of getting them shutdown

Engines were typically toast due to overheating and lack of lubrication from the HIGH RPM

And being up in the derrick when it happened was intense!
How do you have any hearing left? Those old screaming jimmie's were incredibly loud.
rjstractor
Nomad
Aug 24, 2020
RAS43 wrote:
1320Fastback wrote:

The old 2 stroke diesel I had back in the day had like a knife blade air door in the intake to stop it and beleive there was a factory air kill too.

Diesel runaways do happen.

Brings back a lot of memories. Detroit Diesel 2 stroke engines were famous for runaways back then. Either bad blower seals or piston rings could cause it to run on oil. That is why they had an air door on the intake with a pull cable into the cab or the air operated air valve you mentioned. Or a piece of plywood nearby our work station. Also, a runaway could happen if a mechanic set the fuel injector racks too right. That would be a fuel runaway. We kept a hammer nearby to break a fuel line to shut off the fuel and then shut off the air. :R

Yes, and the old Detroit 2 strokes would run backwards too. It wrecked the blower seals if you didn't catch it quickly. Other than the rig moving backwards in a forward gear it was pretty obvious since the cab (old cabover fire engine) would start to fill with black smoke!
JRscooby
Explorer II
Aug 23, 2020
Twomed wrote:

Marine, aviation, train engines, all have positive fuel shutoffs...auto/rv never required.

Your only option is what he did to stall it, which could cause damage, OR pinch fuel line closed with vise grips, OR crack a filter... if you can get to it safely.

He may get lucky.

If a engine is picking up "false fuel", from someplace else, or burning it's own lube for fuel, it does not matter how positive you shut off the normal fuel, it will keep running.
The 2-stroke Detroit Diesel, and old Cats had a butterfly that would cut off air when a cable was pulled. Pushing cable back in did not rest the butterfly.

My first time engine run-away was using military deuce and half air compressor to run a paint gun. The paint vapor was picked up, burned as fuel.
Another thing some diesels can do that can fill the owners pants. If you turn it backwards, or pull it down to a stall and clutch just as it stops, it will start and run backward.
naturist
Nomad
Aug 23, 2020
BobsYourUncle wrote:
Thanks for the input everyone.
Never too old to learn new things.
I'll report back with the end result. Hope it is not too catastrophic.

Too bad, it was a really nice truck.

A wiser man than I once said that any day you learn something is a good day.
noteven
Explorer III
Aug 23, 2020
A diesel is an auto or compression ignition engine. It only needs sorta vaporized or gaseous fuel and air in approx 15:1 ratio to run...

Nowadays this is usually the engine aspirating lube oil through a failed turbo.

A positive air shutdown can save the engine and also prevent a fire or explosion if the engine is breathing external vapour or gas.

These can be automatic or manually operated.

They are also a great theft deterrent. It no start with the shutdown valve closed.

Used on pretty much ever Diesel engine in the oil and gas industry.