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Runaway kill switch

SgtJay88

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Hey everyone. I've been a regular reading posts here but never one to post. I've been doing a lot of work on my deuce and it's in pretty good shape over all but I have a growing concern or fear of a runaway engine. No particular reason I suppose, other than maybe because it's my first diesel but does anyone here have or use a kill switch for the air supply? If so any recommendations on one I can get for it? Is this even something I should be concerned about?
 

NDT

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Old 2 cycle Detroit Diesels had that feature. Never heard of a 4 cycle Diesel engines having it. These multifuel runaways typically happen when the fuel control lever in the injection pump is gummed up from sitting for years. If you drive your truck periodically you should be fine.
 

Mrgior31513

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I've been looking into possibly doing this on mine.

I've been looking at two types: I started off looking at butterfly valves, as they are widely available and have many options for installation. I would use a 6" valve on my truck, as my air intake goes from 6" down to 4", and it shouldn't have any flow restriction given the large down step. While they do have electric ones, I would probably try to make a mechanically actuated one that I could operate from the cab, as the electric ones are a large price jump and I would prefer mechanical for ease of use. Levers tend to be more durable and reliable.

The other valves I've been looking at and will probably go with is a brass piston valve or brass gate valve, as I can easily make a mechanical link up for them as well, and I can get them in NPT or combination NPT/flush mount. Probably still go with the 6", although I could probably get away with using a 4" on my post intercooler side if I really wanted to. Mounting a 6" against the top front fender would give me a straight shot on push/pull for the piston valve, and an under dash linkage would be the simplest version I've been able to come up with. It would also be relatively easy to cover and make even more inconspicuous.


As for my concern: the main reason I've looking into it is because I've just got through building a diesel engine for mine. For the amount of work and money I've put into that build, it would be a decent insurance. Overall cost would be about $4-450. The other reason is that I can make it a bit inconspicuous, and then I would have another "kill switch" that would be quite effective. If I'm going to be away on vacation I could remove a few cotter pins and linkage and it would probably baffle most would-be-theives or joy riders for quite a while.
 

G744

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99 out of a hundred 4-cycle runaways are from turbo compressor seal failures, causing the engine to run wide open on lube oil irrespective of the status of Diesel shutoff.

With the amount in the pan being gallons of oil, it usually pitches a rod from overspeed before running out of "fuel" for it.

Here's an answer idea :

A multifuel deuce has an external air intake on the passenger side, usually a metal mushroom-shaped deal.

I'd make sure the clamp on it was just tight enuf to keep it from falling off, but easy to pull off in a hurry and use a pre-made disk of plywood with a piece of broomhandle screwed to it to block off the air intake.
 

Jinx

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I kept a piece of plywood under the passenger seat that was just big enough to block air intake behind the mushroom cap. If my engine ever would have run away, pretty sure I would have had that crazy "mama's baby trapped under a car" strength and ripped the mushroom cap off, then used the plywood to bock the air intake.

And yeah, the problem with runaways on the M35A2 series trucks were the turbo seals failing and the engine running off of it's own oil.
 

Floridianson

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Old 2 cycle Detroit Diesels had that feature. Never heard of a 4 cycle Diesel engines having it. These multifuel runaways typically happen when the fuel control lever in the injection pump is gummed up from sitting for years. If you drive your truck periodically you should be fine.
Yep! 👍👍
 

SgtJay88

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Thanks for the info and replys everyone, puts my mind a bit more at ease about it. It's my daily so I am doing what I can to get it in the best operating condition possible.
 

G744

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Overthinking anything with an MV is never a good idea.

They were designed to live on, in spite of a young soldiers best efforts to the contrary.

Modifications (if any) had better be done with the wisdom & forethought of the Tank & Automotive Command brains.
 

WillWagner

The Person You Were Warned About As A Child
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Old 2 cycle Detroit Diesels had that feature. Never heard of a 4 cycle Diesel engines having it. These multifuel runaways typically happen when the fuel control lever in the injection pump is gummed up from sitting for years. If you drive your truck periodically you should be fine.
Four strokes had and have them still. If the engines are operated in an environment that has the capability to produce flammable gasses, oil field, off shore oil rig, refineries, not so much anymore, and some land fills, they are equipped with an engine ECM controlled flapper in the intake. Older mechanical engines were operator activated.

The idea of an OX brake would work if one could get the valve to seal tight in the housing, those types of brakes increase exhaust backpressure to slow the engine down so there is a mess of leakage designed into them to prevent valve float when being used.

To be honest, I wouldn't worry about it. Even if there were an air block off installed, there is usually damage done to the engine that will require it to be torn apart to be inspected. Things like valve springs, valves, push rods, bearings, rods, fuel pump internal components like the governor weights and carrier, driven accessories, all take a hit in an overspeed. When the original cause of the overspeed is found and the engine re started, the unseen damage lets itself be known in a hot minute if it is a fuel pump related issue and usually shortly after being put back into service when a valve drops.
 
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