Reason for marine diesel engines runaway

Hi,

I do not know as it doesn't remove the oxygen but works by breaking the reaction between the fires components, it might do something to slow it down.

You are very lucky that you have access to Halon in the US as it is banned most everywhere else.

Halon was great as it didn't gas folks in flooded spaces like CO2 that we have had to return to it having previously been superseded by the wonderful Halon.

Hope I never have to find out if that Halon will work! I like my 820's purring at a nice 1850 rpm

I hope it never happens to me, but I would I figure the engines would need major work or be gone in either case - and I know I ain't going into that engine room to do anything about it! In fact you might see me walking down the dock denying its my boat.

Hi,

Here is a bit of info that explains why the Halon can damage the engine.

233-13.14 DISCHARGE OF HALON IN DIESEL ENGINE SPACE for chap233-rev4

They say every day is a school day, I can't argue with that today.

What about the current stuff? FM200.

Is anybody on a vessel that has the new HI-FOG ultra fine water mist systems?

how about a CO2 fire extingusher in intake to stop a runaway?

What they didn't say is the the flourocarbons in Halon and other refrigerants break down into hydroflouric acid and the exhaust contains phosgene gas ... the stuff that was used to kill troops in WW1.

Any major refrigeration leak will produce the same effects.

Thanks Marmot

If it happens, I'm not pulling my Halon handle!

If ya got access to the air intake, throw a rag in there, or a towel over the air filter on a big engine.

Me, I got a Perkins 4-108 with 1000s of hours and 33 years on the clock and the runaway problem sticks in my mind coming close to a dock..Not

That being said: It sure is a good idea to disconnect the engine and try fore and aft about 200 yards from the dock.
The problem is real, but rare.
Big towel over the air intake should solve it every time and a quick kill if the mate or engineer is briefed.

Well, you have to make a judgement call on that one.

If you have an engine room fire, it will rapidly do more damage in a few minutes than a runaway engine will ever do. If you have a runaway, do you let the engine "grenade" and possibly start a fire then pull the handle?

Or do you hope that the Halon kills the engine which it probably won't since there is still enough O2 to keep it running long enough to pull the gas out of the space?

From what I have seen, very few yachts have the capability of completely sealing an engine room tightly enough to prevent air from reaching an operating engine, and certainly not enough to prevent dilution of Halon with the engine running. That is why there is an engine and ventilation stop feature in a gas flooding system.

The last thing I would worry about is acidifying the oil or gassing downwinders. A quick lube oil change will take care of the oil and the exhaust stinks badly enough that hopefully no one is going to hang around in the cloud long enough to get gassed.

Just for the sake of discussion, I would attempt to block the engine air intake and if that proved impossible, get out of the way until the engine stopped on its own. If it started a fire in the process then that is probably the best time to pull the Halon handle.

There have been a number of references to stopping a runaway engine with a rag. I have no direct experience (thank goodness) with a runaway but based on what I have been told by experienced mechanics a rag probably isn't going to do it. You need something heavier like a board. A rag can get sucked right through. A fire extinguisher isn't likely to do it either as others here have testified. Even if it stops combustion the momentum of the engine will suck enough of it out of the engine room to allow combustion to restart. If you have emergency shutdown air flaps make sure you check them periodically.

Not directly related but in addition to checking for transmission control before leaving or entering a slip I also check that my shutdown (fuel) solenoids are working before I start the engines.

What might be nastier than throwing a rod through the crankcase or watching it detonate in a ball of fire?

There isn't any way to "pull oil up from the sump" and testing the emergency shutdown is just good practice, it's not going to hurt anything since it unloads the blower and immediately slows the engine. The bang it makes as it closes might seem a bit intimidating the first few times but you get used to it.

I remember when it was scary just starting a big diesel, I kind of miss that.

Hi,

I think what you have read is the fact that closing the air supply when one is really going for it can pull the Oil Seals inside out in the Blower Bearing Oil Supply.

This is something the tradesmen used to always go on about when I did my time, as I said previously I have never seen one go mental but have always been very wary of their reputation for doing so when starting one up after working on it.

I think that is another one for the myth file.

Since those are lip seals with the lip outward toward the oil pressure, any increase in differential created by a vacuum on the rotor side will only seal them tighter against the shaft. Not that there could be much of a vacuum at that area anyway since one side of the blower is open to the airbox and cylinders. In addition, there are bearings, a shaft and the center of the lobes between the oil and anyplace a vacuum might conceivably exist.

Hi,

That may be the case but it certainly drove the point home to a few 15 yr old know it alls to pay careful attention to what you were doing with those engines.

Who knows - maybe somebody back in 1938 didn't assemble the seals correctly and had a runaway. After the shutdown they looked at it and said - oh look the shutdown sucked the seals in. "Hey Joe - You put those seals in correctly? Right?"

At any rate you can test the operation of the shutdown dampers with the engines off. On the other hand if you do have a runaway detroit screaming at 4000 rpm the last thing you need to worry about is sucking the blower seals in

so whats the likelyhood of my Mans going run away I'm just a recreational boater. If you read this clip, it seems like we all be should on our toes worrying about this like a clogged racor?

I ran boats every day for 15 years and I have never seen it happen or heard of it happening. I have seen one after an old co2 bottle exploded. It tore that boat up.