Welding gas to snuff engine? - PeachParts Mercedes-Benz Forum

patbob · #1 03-01-2012, 04:55 PM

Before I try to get my car started again (last time it wouldn't shut off), I wanted to pick up something I can use to snuff the engine as a last resort. After pricing CO2 fire extinguishers (very spendy), I realized I could use welding gas -- the argon/CO2 mix is the cheapest and will easily do the job.

So what I'm wondering, is if I have to crack the cylinder and empty the whole thing to stop the engine, or if I can pick up a cheap regulator and air gun so I have some control over the process?

Has anybody tried either way?

mach4 · #2 03-01-2012, 05:19 PM

That would probably work, but I'd sure like to test it in a controlled environment before trying it for real.

Personally, I'd just take the air cleaner off and have a block of wood handy to clamp over the turbo intake to cut off the flow of air.

Cheaper, easier, more positive and already tested. No hoses, regulators, high pressure containers or expense.

Paul

layback40 · #3 03-01-2012, 05:48 PM

Quote:

Originally Posted by mach4

That would probably work, but I'd sure like to test it in a controlled environment before trying it for real.

Personally, I'd just take the air cleaner off and have a block of wood handy to clamp over the turbo intake to cut off the flow of air.

Cheaper, easier, more positive and already tested. No hoses, regulators, high pressure containers or expense.

Paul

X2
Are you worried about a runaway?
A block of wood over the inlet to the air cleaner will slow it down & probably stop it.
If you are in a shop with mig gas as you describe, just have the bottle handy, regulator screwed right down for max flow or if you have a hose that can go straight on the bottle all the better.
If you have a flexible hose from the filter to the IP, clamping that will stop the motor also.

patbob · #4 03-01-2012, 06:31 PM

Quote:

Originally Posted by mach4

Personally, I'd just take the air cleaner off and have a block of wood handy to clamp over the turbo intake to cut off the flow of air.

Cheaper, easier, more positive and already tested. No hoses, regulators, high pressure containers or expense.

D'Oh. It wasn't an option when it wouldn't shut off the first time because I won't work that close to the spinning fan. I guess I kind of forgot it is an option now that I have time to work on it before I restart it. Thanks.

Quote:

Originally Posted by layback40

Are you worried about a runaway?
A block of wood over the inlet to the air cleaner will slow it down & probably stop it.

Not an infinite accelleration runaway, but yes. Last time it was running, it wouldn't shut off. That time, a block of wood over the air cleaner intake wasn't sufficient -- it sucked enough air through other cracks that it just kept idling. Its a very determined little engine

Thanks both of you. I'm still going to pick up a MIG welding gas cylinder to have on hand as a last resort. Since mach4 reminded me that I can block off air at the turbo inlet, That'll be plan A and the welding gas is plan B. If I have to resort to plan B, I probably won't need it a second time.

kerry · #5 03-01-2012, 08:25 PM

Pair of vice grips on the fuel line should be adequate to solve your problem.

vstech · #6 03-02-2012, 10:44 AM

a co2 extinguisher dumps liquid/spray/gas into the engine... relatively low pressure, and effectively shuts down the motor.

mig gas, like Nitrogen or argon would be a HIGH pressure gas, nearly impossible to hold onto a hose attached directly to the tank, and dangerous as well. regulated, it would be insufficient to shut off a runaway motor...

if you can't afford a CO2 extinguisher, lowes sells a co2 tank for about 30 bucks that's for running a nail gun, you could use it upside down for the task...

pawoSD · #7 03-02-2012, 05:27 PM

Quote:

Originally Posted by patbob

D'Oh. It wasn't an option when it wouldn't shut off the first time because I won't work that close to the spinning fan. I guess I kind of forgot it is an option now that I have time to work on it before I restart it. Thanks.

Not an infinite accelleration runaway, but yes. Last time it was running, it wouldn't shut off. That time, a block of wood over the air cleaner intake wasn't sufficient -- it sucked enough air through other cracks that it just kept idling. Its a very determined little engine

Thanks both of you. I'm still going to pick up a MIG welding gas cylinder to have on hand as a last resort. Since mach4 reminded me that I can block off air at the turbo inlet, That'll be plan A and the welding gas is plan B. If I have to resort to plan B, I probably won't need it a second time.

So if it gets down to idling....crack a few injector lines or pull off the fuel hose.....

Orv · #8 03-02-2012, 05:32 PM

When I tested my shutdown plan, I found I couldn't get a good enough seal on the turbo inlet with a block of wood, but a DVD case provided a nearly instant shutdown. The plastic sheeting on the case deforms under suction and automatically tightens the seal.

pawoSD · #9 03-02-2012, 05:45 PM

Quote:

Originally Posted by Orv

When I tested my shutdown plan, I found I couldn't get a good enough seal on the turbo inlet with a block of wood, but a DVD case provided a nearly instant shutdown. The plastic sheeting on the case deforms under suction and automatically tightens the seal.

if the engine is redlining it could suck that case right into the air cleaner.....thats not very sturdy plastic....

wildest · #10 03-02-2012, 08:00 PM

Is this a vacuum shutoff switch problem, or was it trying to runaway when it wouldn't shutdown before?

patbob · #11 03-03-2012, 12:59 PM

Quote:

Originally Posted by wildest

Is this a vacuum shutoff switch problem, or was it trying to runaway when it wouldn't shutdown before?

This is sort of off topic for this thread, but the stop lever wouldn't kill the engine. Could be a bad adjustment, could be its finding another fuel source. Which is why I am asking about welding gas -- if its truely finding another fuel source, then I'll need a way to kill the engine once I get it restarted, and was wondering if I could use inexpensive welding gas instead of buying a very spendy CO2 fire extinguisher and very spendy recharges.

The vacuum shutoff clearly wasn't doing the job either, but I don't know whether I can call it failed yet or not -- something may have failed in the vacuum system such that it wasn't able to get enough vacuum to shut the engine off.

kerry · #12 03-03-2012, 02:03 PM

Vice grips or cutting the fuel line is a real simple solution.

oldsinner111 · #13 03-03-2012, 02:10 PM

Quote:

Originally Posted by kerry

Vice grips or cutting the fuel line is a real simple solution.

In runaway condition it with burn the motor oil as fuel.That why diesels went computerized. to stop runawys.

kerry · #14 03-03-2012, 02:11 PM

Only if there's a way for motor oil to get into the intake manifold. There's no indication that's the case in this instance.

junqueyardjim · #15 03-03-2012, 02:31 PM

Quote:

Originally Posted by oldsinner111

In runaway condition it with burn the motor oil as fuel.That why diesels went computerized. to stop runawys.

Well that is not correct and I don't think it will stop runaway. However most runaways are in the two cycle engine. Patbob, the engine can't get fuel from any other source except through the injectors. I has to be your shut off valve, either a bad adjustment or it needs replacement.