a runaway diesel destroys a beneteau 50. .

[MitchM]

check out captain rick's interview with unlucky owner. . .

curiously, the owner had received advice (after the accidental destruction by fire of his boat) that 'stuffing a sock into the air intake ' is how to stop diesel runaway.

 

[Ralph Johnstone]

Frustrating as hell to listen to. Someone else who just doesn't know the first thing about his engine and has no intention of learning. Has all his maintenance done "professionally" somewhere in the Caribbean. You'll know what this means if you've ever worked in the Caribbean as I have.

I saw a similar video interview to this a few months ago with the same mentality. With this fellow, he had no idea of how the fire started but once again, it was related to the engine. In both cases, the solution was to install large sea water pumps to fight the fire which of course, was always inevitable.

I remember taking a diesel course shortly after getting my boat and within a half hour of the first lecture starting, he instructor launched into the deadly consequences of a runaway engine. Rarely happens, but if it does, the most deadly thing that can happen on an inboard boat if you don't know how to shut the engine down. Something is getting into the crankcase and filling it until the piston(s) are pulling oil into the cylinders.

STOP THE AIR.

 

[justsomeguy]

Sinks in "minutes", yet the video is over a half-hour long!

 

[capta]

I've seen runaway diesels suck in a metal plate specifically designed to stop a runaway, so I doubt a sock or rag would do much good. Never mind sticking my hand anywhere near the intake. Perhaps one of those square cockpit cushions would do better?

 

[Michael Davis]

I've seen runaway diesels suck in a metal plate specifically designed to stop a runaway, so I doubt a sock or rag would do much good. Never mind sticking my hand anywhere near the intake. Perhaps one of those square cockpit cushions would do better?

When my 4-108 did that I knocked off the air cleaner and held a cheese cutting board over the air intake. Worked like a charm!

 

[Ralph Johnstone]

​

I've seen runaway diesels suck in a metal plate specifically designed to stop a runaway

Time to do some arithmetic and see where the problem lies.

We don't know the size of the engine but let's say that the air intake is 3.0" in dia. If the engine air intake were able to pull a perfect vacuum, the internal pressure would be expressed
as 0 PSIA (where A means pressure above a perfect vacuum.) Now atmospheric pressure is 14.7 PSIA (14.7 PSI above a perfect vacuum.) The force across the 3.0" dia. plate would then be :

(π x 1.5 x 1.5) x 14.7 = 104 pounds force

Either the metal plate was made of tin foil or the size of the suction was much larger in diameter to cause the disk to collapse. If you wanted to design a dedicated plate for an air shut off, this is where you would start to avoid collapsing the disk as @capta witnessed. Most likely easier to use a damp towel. The whole towel is just not going to fit inside the filter housing.

 

[Captain Larry-DH]

The whole towel is just not going to fit inside the filter housing.

A brilliant response but I have concerns with this last part. I’d grab something rigid that can’t be chewed up - a cutting board or even the bottom of a bowl or cup.

 

[Davidasailor26]

My Yanmar air intake is about 1.5” and round. Wonder if a conical wood thru-hull bung would work in a pinch?

 

[Michael Davis]

My Yanmar air intake is about 1.5” and round. Wonder if a conical wood thru-hull bung would work in a pinch?

I’m sure! The cutting board I used was about 3/8” nylon/ starboard material. Anything to stop the air except your hand.

 

[garymalmgren]

Cup!
They will be one aboard.
It has a handle to keep fingers out of the way.
It has a flat bottom that should fit the intake end and seal of most of the air.
Great idea.

gary

 

[Ralph Johnstone]

I’d grab something rigid that can’t be chewed up

Yes, yes, yes ................. I was under great pressure in my little back room office as the mighty flames were licking my when that idea came to me. Truth is, just about anything that you can stuff in the air inlet horn is going strangle the engine into stopping. Unlikely anything is going to be ground up as the air filter should stop any fabric coming down the horn.

Wonder if a conical wood thru-hull bung would work in a pinch?

Hardly a pinch. More like the bung was custom made for the job. I don't know what minimum % of air is required to quench the fires in the heart of the beast but the tapered bung would quickly form a near perfect seal.

 

[jssailem]

The importance of this exercise is to acquaint all with the subject.
Trigger ideas that will resolve the problem.
At least having identified the problem and developed some solutions should this happen we are ahead of the poor souls who are clueless.
Thanks @MitchM for the post and the ideas from all on ways to solve this challenge.