Off topic about a Semi tractor turbo and blown motor

[Canada_CT230]

At my old job I used to be a safety officier and we had to have Run-Away cut-offs installed because our trucks worked oil field leases. A cab switch actuated a guillotine on the intake. That would cut-off all air to the engine in the event of a run-away.

 

[Ryan03]

Natural gas can cause the same type of runaway situation on diesel engines. It is not at all unheard of to have back hoe or excavator engines runaway when a gas line is hit and breached. The only way to stop the runaway before it destroys itself is with the intake baffle mentioned by Canada CT230, or some other means of cutting off the air supply.

 

[The Haymaker]

Natural gas can cause the same type of runaway situation on diesel engines. It is not at all unheard of to have back hoe or excavator engines runaway when a gas line is hit and breached. The only way to stop the runaway before it destroys itself is with the intake baffle mentioned by Canada CT230, or some other means of cutting off the air supply.

That's part of what destroyed Deepwater Horizon. The diesel generators sucked gas escaping from the well head. I remember reading that in the survivors accounts.

 

[Renze]

Had that a few times on a Ford Sierra 1.8 turbodiesel i drove for 2 months... when i got off the highway onto the next, it would be at temperature. when i accelerated on the on-ramp again, it would blow oil past the turbo seals, allowing it to smoke blue, knock hard. I put it in 5th gear and braked it to stop. after a minute i could continue the drive to work.
We wanted to jump it after that, but the engine died altogether shortly after... In hindsight it may have been because i never checked how much oil it guzzled those last 2 weeks...

 

[Reg]

Bad call on my part, as my dispatcher is on vacation and the lady trying to do his job wouldn't have a clue about it, and although I thought about it after the fact, had no clue that something like that could or would have happened. I really hate that my lack of knowledge about a truck related incident could have cost the company that much money. Being in trucking for as long as I have, would have (should have!) given me a clue as to shut that thing down when the turbo went and it started smoking! Unfortunately I have not been exposed to run away motors in the past, to even consider the causes and reasons. The old saying "too soon old, too late smart" sure applies to this one.
David from jax

Don't be so hard on yourself.
Run away motors are (to MOST people) little more than urban legend, to others a once in a lifetime experience.

SOME trucks are actually shut down (key off) by de-energizing a solenoid valve on the surplus fuel return line.
Yeah, sounds weird at first, but the motor is stalled by being "flooded" with fuel.
I don't know what happens with this system in a run away scenario, it might make it worse, it might work very well.
I could speculate, as can others.

Point is you are the driver, not the design engineer or the tech/mechanic.
You can equip yourself with a lot of knowledge, some of which you will never use.
You can't equip yourself with ALL the knowledge that you MIGHT be able to use.
You can't know every engine's fuel design or potential disaster scenarios.

"Stuff a coat in the air cleaner" is no longer the cure all for a run away motor - and quite frankly I doubt that it ever really was (-:

 

[Renze]

Yeah, sounds weird at first, but the motor is stalled by being "flooded" with fuel.

That applies to gas engines maybe. Gas engines require an air/fuel mixture of 1:23.5 to 1:24.5 to ignite. Diesels dont, you can put in as much fuel as you like, and it will run as long as it doesnt hydrolock...

"Stuff a coat in the air cleaner" is no longer the cure all for a run away motor - and quite frankly I doubt that it ever really was (-:

Last time i had my propane powered car for a DMV test it was: the inspector stalled the engine by putting his hand in front of the air cleaner suction tube. That stalled the engine within 3 seconds, he did this to check if the electric solenoid valve on the propane tank would cut off the gas flow immediately after the engine stopped, which is mandatory for safety.

I had a colleague who worked at a crane company, and they had a crane with a Mercedes V8 diesel that didnt shut off due to a broken shut-off solenoid. He tried to stall it by pulling all 4 hydraulic crane levers at once. The effect was that the engine kicked back and began running in reverse: The pumps also turned backwards, pumping the oil back into the tank and sucking air, so it wasnt possible to stall it again. Or at least, have it kick back into forward motion.
Anyways, before he could grab tools to open the hood and rip off a fuel line, the engine had already damaged its crankshaft bearings because the lube oil pump also ran in reverse, draining all the oil from the bearings.


Lesson to learn: Even experienced mechanics can create a lot of collateral damage by unforeseen events...

And with that automatic transmission, there is no way you could have stalled it, the transmission oil would have boiled out before the engine went and both would be toasted...

I hope your boss has additional insurance that covers this.

 

[JESSE1]

Blew an oil seal on a 350 Cummins in a '74 White Freightliner. Started off from a stop, turbo started making a bad squealing noise. Turned around to head to the shop and the truck caught on fire, evidently oil sprayed on exhaust manifold. Only two blocks from a fire station but by the time they got there the fire had gutted the cab. Also had full fuel tanks, 200 gallons of diesel but they didn't catch on fire. Company had the truck interior replaced and we drove the truck for several more years.

 

[56FordGuy]

And with that automatic transmission, there is no way you could have stalled it, the transmission oil would have boiled out before the engine went and both would be toasted...

I don't know exactly what type of transmission the original poster has. All the 'automatic' transmissions I've worked on in semi trucks are not the same thing you will find in a car or even a pickup truck. They're automatically shifted manual transmissions. They still have a clutch, and they shift gears on their own using an electric motor instead of a shift handle in the cab. Some of the early models still had a clutch pedal that the driver had to use when stopping, but the later ones didn't. They drove just like the automatic transmission most folks are used to.

I didn't like them. You could count on replacing a clutch around 200,000 miles. Our manual trucks were running twice that on a clutch.

 

[77bronco]

The two-stroke Detroits had a manually operated spring loaded flap as a emergency shutdown in case of a runaway, but our instructor at mechanic school at Camp Lejuene told us that it was for all practical purposes useless. He said that if the engine was running away, activating the flap would just cause the blower to suck oil past the seals and keep feeding it until it self destructed. Luckily I never had to test that theory.

Stuffing a coat into the intake to shutdown a runaway does work.Back around 1990 my 6.9 Ford lost the seal at the back of the injection pump and was leaking fuel into the oil pan. When the oil got hot enough to start vaporizing the fuel it would pull it into the intake. I was watching the mechanics at the dealer troubleshoot it, when it started to howl, and one of the older guys shoved his coat into the air cleaner intake. It pulled the air cleaner down about two inches, but it did shut it down. I don't know if this would work on a newer diesel, but it worked on my 6.9.

 

[Diamondpilot]

Last thing I would do is get anywhere near a run away diesel engine. No way in heeellll I am going toward it, I am running the other way. In about 2006ish is saw the results of a new 6.7L Cummins running away at a diesel shop here in town. They are one of the most respected Cummins shops in North America and when this motor was introduced there was a learning curve for the guys everywhere. Anyway it was not pretty when it went.

The motor can easily be replaced but trying to save it is just plain stupid. Its a bomb when it starts running away. Same can be true or a jet engine or turbo prop engine on so many of the airplanes that I operate for a living. I want to be far far away behind something solid if it decides to have a mind of its own.

Chris