OT: MY Runaway diesel tractor almost gave me a heart attack today

[tomjelly]

Mowing the lawn with my New Holland 33hp hydrostatic diesel tractor today and saw a small puff of smoke from the exhaust, which it never does. Turned off the key and it went to full screaming throttle. Key is in my hand and I'm standing there like an idiot with thick black smoke billowing out, hot oil spraying out now, knowing this motor is going to explode, its screaming. Back away to a safe distance to await the inevitable. 30 seconds later it turns off by itself, oil is everywhere, I supposed it has siezed. Tow it to the shop, clean all the oil off. Crank is movable...Dipstick level and oil color look fine, take off the filter housing from the metal manifold, looks fine & dry, throttle linkage works fine, remove valve cover no shrapnel, looks good under there, radiator pressure test OK. Hydro oil level does not register on dipstick. Stick a wire in there 6" longer than the dipstick and it comes up dry. Hydro pumps run off a common drive with the injector pump- but doesn't look like oil could make its way there- maybe a pump seal leaked into the drive? Open up the air filter housing for a look at the filter and its soaked with oil & a lot of oil inside the housing- but NO oil in the snorkel. Hydro low pressure oil cooler is in front of the radiator, under the snorkel. Thin split in the rubber hose elbow to the cooler only detected by pressurizing the cooler and its associated hoses when removed. Split is big when pressurized. Apparently a stream of hydraulic oil sprayed out of the split in the hose, deflected off the hood and a portion of that stream shot into the air snorkel, fueling the motor until it emptied the hydraulic reservoir- either that or an oil mist from the leak got sucked in. I haven't started the motor yet, but hopefully it was not damaged- my shorts, not so much. Still not sure how the snorkel could be dry & filter housing be full of oil- must have been a mist. Those elbows are about the only soft lines on the machine, almost all of the rest is steel line. Looks like fabric reinforcement, will replace with better stuff for sure. Even if I could have braved the 9 gallons of hot oil spray I doubt if I could have choked off the engine with he snorkel designed as it is. I read now that diesels in critical applications are supposed to have air intake shutoff valves. Might be a good idea for any diesel...

Check your hoses....

t

 

[Philabuster]

CO2 fire extinguisher sprayed at the intake will also safely kill a diesel engine runaway.

 

[rjs44032]

Damn,

Glad you came away unscathed.

Best Regards,
Bob

 

[Milacron]

I experienced a runaway Yanmar 3 cylinder diesel on a sailboat a few years ago. Boat was docked in marina but still scary as the RPM got worse and worse. I put a piece of plywood over the air cleaner intake but it still sucked air thru the tiny gaps between air cleaner lid and housing. Was creepy, like the engine was determined to be "alive" no matter what. Finally got the fuel line disconnected in time before the engine self destructed.

 

[mark costello]

You guys just cured me of ever wanting a Diesel engine.

 

[Mike Folks]

I've read about the same thing happening on the Diesel Electric freight locomotive, when they start to consume the engine lube, kinda scary when something that big is increasing the rpm's by the second. I'm not that familiar with the GE Diesels, but the former EMD(now caterpillar) big engines are 710 cubic inch per cylinder, add 16 or 20 cylinders howling at almost destruction speed, and it'll scare the pants off anybody who knows what's going on.


This is an air start of a 20 cylinder 710 at a power plant, the same engine used insome freight locomotives.
EMD V20-710 Start-up and rated load - YouTube

 

[Milacron]

You guys just cured me of ever wanting a Diesel engine.

It's really a pretty rare event. In my case the engine was rebuilt but rebuilt like 5 years earlier and sitting all that time. Been so many years now I can't remember but I was doing something to free up stuck injectors or stuck something. A typical diesel engine that is used normally with normal maintenance is never going to run away.

 

[tomjelly]

I would definitely consider a boat motor one of those engines that should have an intake shutoff valve. I'm sure there are some on the bottom with hulls perforated by engine parts!

 

[GregSY]

Seein's as how you wasn't gonna be wearing 'em anymore, you coulda stuffed your underpants down the intake.

 

[tomjelly]

Reading more on the subject I see that a partially blocked intake can cause some systems to suck fuel from the injector return line and run away. My situation was unusual, low hours on the machine but I think the hose was not spec'd correctly. There are pics on line of a locomotive in runaway mode. I also heard about one where there was a runaway diesel excavator- source of fuel was hitting a natural gas line! Talk about an oh sh*t moment....

 

[jhruska]

I did inspection for *****-******/******* ***********, turbochargers.
The center housing seal is a carbon seal. At the time, the seal would not always seat. Oil would pass into the compressor side, travel to the intercooler and worse case, fill it. The assembly line practice for the engines produced (at a company I'd better not name) would be to assemble the truck or school bus and get it to a point where the engine could be started. Then the vehicle would be driven to each station on the assembly
line. In the worst case, oil would supplant the diesel fuel supply and the engine would start to overspeed. The line mechanics would shut off the fuel supply but to no avail as the engine was consuming its own crankcase oil.
John

 

[scadvice]

Wow... this is a new one on me. I wish my dad was still alive. I love to ask him about this. he was a heavy equipment diesel mechanic. He would love this kind of sh!t.
Great logic to jhruska's post!

Steve

 

[Garwood]

I had a 4BT Cummins stick the fuel rack once. It was normally governed to 4000, the RPM that sucker was zinging was unlike any diesel noise I'd heard before or since. I cut the fuel supply line with some dikes to kill it, but part of me wanted to see how high it would go. It's still out there driving around somewhere.

 

[dkmc]

Holy Moley and LOL

Your mower should be fine, but you get a dope slap and wuss-bang kick in the butt for standing there and waiting for it to blow.......instead of thinking fast and trying to stall the engine........somehow!


I was in a heavy truck repair garage once......they just finsihed rebuilding a 4-71 detroit and started it up. Something about the fuel rack was in "backward" or whatever.

That engine took off......and headed for the sky.
Young mechanic was standing near, and froze in place.

Older guy across the shop, took off on a dead run, grabbed a cookie sheet type parts tray on his journey, shook off the parts that were on it, and promptly stuck it on the open intake of the blower.
Saved it from grenading.

Never heard such a sound before or since, and the smoke that filled the shop was impressive as well!

dk

 

[bjorn toulouse]

This is an air start of a 20 cylinder 710 at a power plant, the same engine used insome freight locomotives.
EMD V20-710 Start-up and rated load - YouTube

30 odd years ago I was an Asst. Engr. on an off shore, semi-submersible, rig.
The engine room had five EMD 16-645s, (3000HP @ 900RPM).
When ever they were trippin' pipe (pulling a long drill string out of the hole), I'd go down to the engine room and stand betwixt a couple of the EMDs. Nothing like big, hard workin' horse power to make the little hairs on your neck stand up!!!


Rex

 

[steve-l]

This phenomena rarely happens on 4 stroke, naturally aspirated diesels. It is still relatively rare, but when it occurs, it is almost always on 2 stroke and supercharged engines. The most common cause is seal failures of the rotor shaft end seals of roots blowers and impeller shaft seals on turbos. A more remote cause is wrist pin end seals on Detroit Diesels, where piston coolant oil flows to the outside of the piston above the oil control rings and then finds its way into the airbox via the transfer ports in the cylinder. Most marine engines have spring driven air control flaps above the blower that can be remotely tripped. However, these are options and must be specified when buying the engine. I have never seen these on fan to flywheel engines.

 

[Timw]

Holy Moley and LOL

Your mower should be fine, but you get a dope slap and wuss-bang kick in the butt for standing there and waiting for it to blow.......instead of thinking fast and trying to stall the engine........somehow!


I was in a heavy truck repair garage once......they just finsihed rebuilding a 4-71 detroit and started it up. Something about the fuel rack was in "backward" or whatever.

That engine took off......and headed for the sky.
Young mechanic was standing near, and froze in place.

Older guy across the shop, took off on a dead run, grabbed a cookie sheet type parts tray on his journey, shook off the parts that were on it, and promptly stuck it on the open intake of the blower.
Saved it from grenading.

Never heard such a sound before or since, and the smoke that filled the shop was impressive as well!

dk

The old Detroits are known for starting backwards.
I drove an old GMC Semi and had it start backwards a number of times while backing under a heavy loaded trailer. Engine would stall and turn backwards as I was shot back out from under the trailer.
They can also start backwards if on compression stroke and kick back.
The bad thing is it will set air cleaner on fire and the oil pump is not working!
The GMC had Engine Stop (fuel) and Emergency Stop (Air intake shut off).
If you remember the reports from the BP Rig in the gulf, they said the first thing to happen was the generators ran away from injesting gas (NG, LP ??) from the well.

 

[sealark37]

On the rare occasion when an earthmover cuts a natural gas line, the diesel sniffs the NG, it is time to abandon ship. I have seen the results of two instances. Both tractors reduced to scrap. Regards, Clark

 

[Milacron]

Seein's as how you wasn't gonna be wearing 'em anymore, you coulda stuffed your underpants down the intake.

That is funny...but FWIW, I wouldn't recomend stuffing any sort of fabric down an air intake on a runaway engine. The suction is unbelievably strong during a runaway diesel incident and it may suck the fabric right into the cylinders. Even with a screen in the air cleaner it can suck so hard it can tear the fabric to bits and suck beyond the screen.

Plus the underwear may have saved his pants

 

[KB3AHE]

they actually made engines for natural gas line pumping stations that ran on that principle. They were very large diesels that had terribly undersized fuel injection systems. They started up like a diesel, given just enough fuel to idle and ran on the NG. The diesel combustion was used just to fire off the NG and act like an ignition system.


Old 2-cycle Detroits were notoriously easy starting. They would fire off if you just shook the crankshaft, much less spin it over. (A real blessing on a cold winter day!) Many people have been injured just simply "barring" them over by hand to adjust the valves or the fuel injection "rack" clearances. They are also more likely to "run away" as they get older and more worn. Crankcase oil will pass by worn rings and acumulate in the air box. Once you accumulate enough in there, LOOK OUT!! Sometimes on a worn engine, the air shut off will make it worse as closing it off will cause it to suck even more crankcase oil into the air box.

but....... Say what you will, I will always have a warm spot for 71 series Detroit Diesels, especially 6-71s! !
And....Furthermore, if you have ever heard a 12V-71 run right up against the governor with open stacks, It's a sound you wont forget for a while!

Frank