Kill the Engine...or Maybe Not??

[rmoore]

Received this question from a vehicle rescue instructor in Virginia. What suggestions can you offer from your experiences?

Question-
How can I shut down a Mercedes that wont shut off? It was an '86. Been crashed. Key was off. I stuffed a rag in the intake and it still ran?????? Dry Chemical????


Reply-
Was it a gas or diesel?

I would have thought that the stuffed rag technique would work no matter what.

The dry chem is an 'oxygen starving' agent just like the rag so even though I think I would have tried that next, it might not have worked either.

Spark plugs or the distributor cap is a possibility on a gas engine.

Plugging up the tailpipe might stall out the engine.

Putting the vehicle is gear with the brakes set may stall it out if it is only running just above idle.

By the way, what did you do to get it to stop?

[SPFDRum]

Mercedes is a leader in auto-tech, so even then, that car may have had a distibutorless ignition?

Maybe a CO2 extinguisher discharge into the air intake?

[kevinw]

Mercedes Shutdown

http://cms.firehouse.com/forums2/sho...7&pagenumber=2

Here's a link to a discussion some time ago. On it's 2nd page there's a picture posted of the engine kill switch I found on an older Mercedes that would not stop running (until we pushed the switch). It was a diesel engine. Sounds similar to this guy's inquiry.

[JorgHeck]

CO2 in the air intake works well, also on big rigs!

Newer cars could have (mercedes benz) could habe a system called "keyless go" which works without a key. The driver only carries a key-card in his pocket and could start and stop the engine with a button on the gearshift-lever!

[NB87JW]

KILL Switch

Kevin,
Great memory on the January post. We had a smilar experience several years back with a bigger (truck) diesel engine the was actually running backwards (has any one else ever seen this?) when we arrived. We had no kill switch we could find. In the end (after a quick extrication) we clamped the fuel line and starved the engine (which was already running VERY rough).

By the was does anyone know EXACTLY what that Kill switch does to stop the engine? Maybe we can duplicate it on other future engines whilst <----(learned from lutan) performing our extrication evolutions. (Jorg?, 101? any ideas?)

The photo you submitted in March for the thread link was so good I hope you don't mind me borrowing it for here. Great Input Kevin.

See you soon?

Be safe all.

Fraternally, Jordan



(Kevin W's "kill switch" photo below in a Mercedes)

[rmoore]

I did receive a follow-up message from our Virginia instructor regarding the actual incident. Here's an excerpt;

"It was a diesel and a person was trapped in it. We did the dry chem, glove and after pulling a bunch of wires, the car cut off 5 minutes later."

[MikeF25]

If I remember correctly a vehicle running backwards is called dieseling. I believe it happens when an engine loses time. I could be wrong though.

Anyway, obviously the hood could be opened. So was there a fuse box under the hood? If there was there are a couple of fuses that when you pull them out the engine will stall, same as the fuse box in the interior of the vehicle, if they are accessible.

[HFRH28]

Generally, in older gassers, you can pull the wire going into the middle of the distributor, and it will die. Now in Distributorless ignition, you can just start pulling plug wires, and it'll eventually cut off, or if you know what you're doing there are other ways. I've seen a few cases where removal of the negative battery cable will cut it off, but some vehicles will run without a battery being hooked up. With turbocharged diesels, if there is any kind of seal leaking, and you cover up the air intake, it will run off of itself, but if the seals are good, that will not happen. An easy way to get a tractor to shut down is put it in the highest gear, and hold the brakes, and get off the clutch.

As to the engine running backwards, it had to have been a 2 stroke, because two strokes can run backwards.

But i would still like to hear some other ideas on how to shut down newer gassers and diesels.

[Rescue101]

Be very Careful

Be very careful messing around with newer distributorless ignitions.Old systems used to produce about 25k spark volts.The newer systems can produce upwards of 60k or better and will throw a spark over and inch and a half.They will bite you bad and if your shock intolerant you could have a real problem.As far as diesels running backwards the old Detroit Diesel two strokes can do it with ease,the problem is when they do exhaust becomes intake and visa/versa.At this point they begin burning their own LUBE oil for fuel.There is ALWAYS a redundant shut off on these engines.Most times both will be on the control panel,one will be labeled Emergency.The regular shut off kills the fuel at the govenor,the Emergency is a one shot resettable trap door at the air intake of the Roots blower.When you pull the Emergency the trap door closes at the air intake of the blower.Before the engine can be restarted the door must be manually reset.These old motors had occasional "runaways"hence the E-shut down.Most modern diesels shut down electrically thru a fuel cut solenoid.If it's not working generally the only other way to shut them down is by starving off the air supply.A trash bag around the air cleaner intake or inlet tube is usually reasonably quick and effective.A good blast of CO2 should also work well while causing no engine damage.Pulling wires would be my last resort as you can get hurt if you happen to pull the wrong one.Hope this helps.T.C.

[HFRH28]

Not to get completley off subject, but when an 2 cycle runs backwards, intake still remains intake, and exhaust still remains exhaust. When running backwards it is running off of its own lube oil, and there is zero oil pressure. When a 2 cycle diesel runs backwards, it puffs blue smoke from the exhaust stacks. A trash bag will not always stop a diesel, such as the 450 horse cat. Today i heard a story about a 450 horse cat, where a 1/2" phone book was put over the intake to choke it down, and it sucked in the phone book.

[nmfire]

So what your saying is, I should put a copy of the Manhatten white pages on the rescue truck?

[Rescue101]

Guess again

Hfr,Think your statement thru carefully!How does a two stroke breathe?Via the Roots blower.If it's running BACKWARDS, SO IS THE BLOWER!Intake becomes exhaust or at least that's where the smoke comes out.I own a 8V71 and I formerly worked as lead mechanic for a contracting company that ran numerous DD.And I'm not talking about a K-mart special trash bag,I'm talking about a FD type bag like you would use for Haz-mat clean up.Having shut down several large HP diesels using this method I know it works.NO you DON'T put it over the inlet TUBE (they'd suck down a horse)rather the AIR CLEANER.At IDLE this will stop 500 Cats,650 Cummins,8V92 Detroits,or the 466 Int. diesel.Working around heavy equipment every day you quickly find out what fails and fuel cut solenoids are right at the top of the list.Ever see a Detroit powered 1400CFM air compressor "run away"?I have and it isn't pretty.T.C.

[HFRH28]

The Detroit I saw ran backwards still smoked from the stacks.... Because of the way a 2 stroke is designed, it can run backwards, and still suck in through the intake, and still exhale through the exhaust, Such as a model airplane engine.... They love to start backwards. They breath in the intake, and out the exhaust.

[Rescue101]

Quite true to a point,however as you pointed out you will have 0 oil pressure and you WILL have some smoke out the intake/air cleaner which you will NOT have when they are turning the right direction.I've even seen 4 strokes run backwards although poorly and not for long.Funny thing is on the old diesel tugboats that's how they reverse them,they run the motors backwards.T.C.