Safe Ways to Shut down Run away Diesels - PeachParts Mercedes-Benz Forum

Aquaticedge · #1 10-28-2010, 02:42 AM

There's been a few Topics on here of Diesels that wont turn off the normal ways IE stop lever or Off with the key, So, What is the safe ways to Kill a diesel without Destroying the motor

Some ways Discussed

Blocking off the air to the engine

Post your ways you know of that is safe to do, to Shut down the engine if the need arises

turbobenz · #2 10-28-2010, 03:46 AM

obstruct the intake and if theres still enough air leaking through the air cleaner for it to run at a reduced speed calmly walk to your box and get a wrench for the fuel hard lines. You can even use your hand in a pinch to obstruct the air cleaner (but of course never the turbo)but the vacuum gets intense

turbobenz · #3 10-28-2010, 03:48 AM

ive also heard a co2 fire extinguisher works the best

Stretch · #4 10-28-2010, 03:54 AM

Quote:

Originally Posted by turbobenz

ive also heard a co2 fire extinguisher works the best

I'm sure that it works - however putting ice cold gas (a gas under pressure will cool under expansion) into a hot engine may induce metal fatigue - so I would argue that this could be borderline unsafe...

layback40 · #5 10-28-2010, 04:40 AM

On GM 2stroke supercharged diesels, like the one in the tank that that mad guy in Kelley's Heros had & lots old buses had, have a kill leaver that shuts a butterfly in the air inlet. Normally when you restrict the air, it brings the motor under control & it can be shut down, have done it a couple of times on a GM 8/71. It feels like it goes from 330hp to about 1000hp. I once had a turbo Isuzu run away while I was driving it. I braked as hard as I could & it came back under control. Scared the C##P out of me.

Aquaticedge · #6 10-28-2010, 04:49 AM

Quote:

Originally Posted by layback40

On GM 2stroke supercharged diesels, like the one in the tank that that mad guy in Kelley's Heros had & lots old buses had, have a kill leaver that shuts a butterfly in the air inlet. Normally when you restrict the air, it brings the motor under control & it can be shut down, have done it a couple of times on a GM 8/71. It feels like it goes from 330hp to about 1000hp. I once had a turbo Isuzu run away while I was driving it. I braked as hard as I could & it came back under control. Scared the C##P out of me.

Same thing sorta happened on my old Isuzu wrecker, the Tread seporated from the tire and took with it the rear throttle control (Hydraulic Pump was engine driven) so in essence the engine was floored, we braked hard and got to a safe area. lucky for us it was a simple Disconnect to the rear line and the engine shut off with the key past that

W124 E300D · #7 10-28-2010, 05:49 AM

Quote:

Originally Posted by layback40

On GM 2stroke supercharged diesels, like the one in the tank that that mad guy in Kelley's Heros had & lots old buses had, have a kill leaver that shuts a butterfly in the air inlet. Normally when you restrict the air, it brings the motor under control & it can be shut down, have done it a couple of times on a GM 8/71. It feels like it goes from 330hp to about 1000hp. I once had a turbo Isuzu run away while I was driving it. I braked as hard as I could & it came back under control. Scared the C##P out of me.

typically when you pulled that flap on the detroits it did shut the engine down (first time) but also sucked the oil seals out of the blower, so second shut down less likely to work, etc etc... too many pulled that lever when it wasn't really needed, too few did a proper rebuild afterwards.

W124 E300D · #8 10-28-2010, 07:00 AM

Quote:

Originally Posted by Aquaticedge

There's been a few Topics on here of Diesels that wont turn off the normal ways IE stop lever or Off with the key,

This is NOT a runaway diesel.

A runaway diesel is an engine that is running on fuel OTHER than that injected through the injector.

layback40 · #9 10-28-2010, 08:15 AM

Thats true w124,
If its just sitting there idling & wont stop, first thing would be to use the stop leaver on the IP. If that didnt work, start cracking the hard lines on the injectors. Its quicker than shutting the fuel off by disconnecting the fuel hose.
Probably putting your hand over the air inlet may work.
You may be able to suck on the vac line that goes to the shut off diaphragm.

soothappens · #10 10-28-2010, 09:00 AM

On the race trucks they use a spring loaded plate in front of the turbo.
Its called a guillotine.

Only for a runaway though.

What your describing as others have said is a bad stop diaphragm.
Mercedes made that one easy big red sign on the linkage that says STOP.

kerry · #11 10-28-2010, 09:30 AM

If it's running on its normal fuel, cut or remove the fuel line. The engine will stop once the lift pump has no incoming fuel to pressurize the line to the IP.

scottmcphee · #12 10-28-2010, 10:18 AM

It's a runaway runaway diesel thread.....a a aaaaHHH..

The ONLY way to surely stop a runaway is starve air intake. As in, slam it shut.

This is why in the open pit mines around here, at the gate there is a vehicle checkstop and if you are driving a diesel the guard will demand you demonstrate the shut off, in fact, he asks where the button is and hits it. The engine has to stop NOW. He opens the hood and looks for the slam gate and that it is closed .... then you can reset it and continue on with a day pass sticker on your windshield.

Here's how I'd do it on my 87 300D: turn the air meter box around so the flow is backwards, and pin the flap open for normal operation. Pull the pin, and slam! The spring shuts the gate and air intake vacuum will pull it shut stronger. Rig a cable pull line from the pin to a dash mounted knob that you pull.

The air meter box and its sampling sensor are not needed / no use if you've done like many people and disconnected the two vac pods on that side of the car. My box is currently sitting on the bench and I have a 3" straight pipe in this spot.

strelnik · #13 10-28-2010, 03:53 PM

Quote:

Originally Posted by turbobenz

You can even use your hand in a pinch to obstruct the air cleaner (but of course never the turbo)but the vacuum gets intense

NEVER USE YOUR HAND!!

NEVER DO THAT!
IT IS UNSAFE!
PULL OFF YOUR SHIRT IF YOU HAVE TO, BUT NEVER USE YOUR HAND!

W124 E300D · #14 10-28-2010, 03:58 PM

Quote:

Originally Posted by strelnik

NEVER USE YOUR HAND!!

NEVER DO THAT!
IT IS UNSAFE!
PULL OFF YOUR SHIRT IF YOU HAVE TO, BUT NEVER USE YOUR HAND!

Agreed.... a runaway is basically a vacuum pump, it will pull 15 psi of vacuum (near as dammit) almost instantly.

a 3" diameter intake has a surface area of 3.14 x 1.5 x 1.5 = 7 and a bit square inches.

7 x 15 = 105 pounds of suction force, applied BAM just like that.

Aquaticedge · #15 10-28-2010, 04:04 PM

add to that a turbo spinning at speed is basically a food processor.... eesh