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It is currently the year 2059. 97 years ago, the Cuban Missile Crisis went hot, and nuclear war between the USA and USSR became a sudden reality. The people alive now are 3rd and 4th generation wastelanders, most of whom have never seen any vehicle move, aside from horse pulled carts.

In New Mexico, there are a group of paramilitary known as “The Snipers”. They task themselves with protecting the people they can in wasteland, using old world tech and some weapons they manufactured themselves. But, they also have a more ‘scholarly’ branch that tasks themselves with revamping and reusing old war technology that they can use for their cause.

Two scouts recently found an old world truck, submerged in some ancient mudslide, so intact the skeleton of the driver is still grasping the wheel. They told HQ about it, and they’ve sent their top men to try and get it moving again. They don’t have access to petroleum products, but they think they may be able to make it run on steam power.

My question is, could a modern day (or 1960s) truck be re-engineered to run on steam power?

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    $\begingroup$ When you say re-engineer, do you mean take a truck that currently has a diesel engine and turn that into a truck that operates on a steam engine? They would basically have to replace the entire engine. There have been trucks that have been designed to run on steam from the get go though, like the NAMI-012. $\endgroup$ – Pasqueflower Dec 31 '18 at 0:56
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    $\begingroup$ If the truck has a petrol (gasoline) engine, they may fit it with a wood gas generator, which can be used as fuel in petrol engines. A steam engine has nothing in common with a petrol or diesel engine; nothing fits, not the cylinders, not the pistons, not the transmission. $\endgroup$ – AlexP Dec 31 '18 at 3:21
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    $\begingroup$ Probably easier to use biodiesel or ethanol. $\endgroup$ – GrandmasterB Dec 31 '18 at 4:17
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    $\begingroup$ This appeared in the VTC queue with a vote for too story-based. It might not be about worldbuilding (after all, what rule of the world is the OP talking about?), but too story-based? There are very practical, non-story-dependent reasons both supporting and refuting the ability to do this, so I disagree with that vote. $\endgroup$ – JBH Dec 31 '18 at 8:52
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    $\begingroup$ It would be a lot easier to simply rejig a petrol engine to run on bio-diesel, alcohol, or methane, so not sure why they'd bother choosing steam, that aside the entire engine would have to be replaced from scratch, the only bits you'd be keeping would essentially be the chassis, the wheels & some gear shafts, "repair" in that context really wouldn't be the appropriate word :) $\endgroup$ – Pelinore Dec 31 '18 at 15:15
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So, first thing to get out of the way.

The engine in it's current format will not run. At all.

Every rubber part would have perished, the bores in the engine would have filled with mud and rusted. Every bearing, the timing gears, the lifters, everything would be rooted.

Even if you were to completely dismantle, sodium blast and repair all these components at great expense, you would still be missing the new parts required to make it run. Gaskets/seals, belts, hoses etc would be difficult if not impossible to come by.

If the vehicle had fallen into a tar pit or something, there may be some hope in it not rusting into oblivion. But 90 years under the mud will result in very little salvagable truck.

The main part of your question, however, is whether you can re-engineer a truck to run on steam. The answer is yes, a single-piston steam engine is a fairly simple device that could be constructed out of scavenged materials. Steam powered trucks, cars and tractors have been built around existing platforms over the years and is entirely possible.

See wikipedia for a broad run-down: https://en.wikipedia.org/wiki/Steam_wagon

Also read up about Edward Pritchard, who made a name for himself converting existing vehicles to steam power: https://en.wikipedia.org/wiki/Edward_Pritchard_(engineer)

It would be by no means easy to do in a limited resource world, but if someone happened to know how steam engines worked they could certainly build a home-brew steam vehicle.

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There were some cases when coal-fired trucks were done (albeit in factory conditions) during WW2:

http://www.robertsarmory.com/gas.htm

google for "ZIS-13 gasogenerator" as well

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    $\begingroup$ Gas generators do not generate steam, they generate producer gas or wood gas which is then used as fuel in regular petrol engines (albeit with abysmal efficiency, low power etc., but then it was war time and low power is infinitely better than no power). $\endgroup$ – AlexP Dec 31 '18 at 3:20
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    $\begingroup$ true, but still a feasible option for OP to consider. $\endgroup$ – aleck Dec 31 '18 at 3:57
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Short answer is yes. As long as they had a way of making a new camshaft. Dunn-right and others have offered kits for a long time which take a 4-stroke engine (a VW engine in this case) and add a different camshaft to turn two of the cylinders into an air compressor; the only difference between an air compressor and a simple steam engine (i.e. no valve cutoff control) is the compressor is turning the crankshaft to pump air out, while the steam engine is letting steam in to turn the crank (an air compressor can easily be turned into a steam engine, although the crankshaft turns in the opposite direction).

Also, you didn't specify if it had to be a typical diesel truck. They're not too common, but a number of trucks have been built with 2-stroke engines (both petrol and diesel) there are videos on youtube of them like this Kenworth fitted with a Detroit Diesel v12 2-stroke (the noise they make is wonderful).

There are also a lot of videos on youtube like This one of people converting small 2-strokes into steam or compressed air engines. So it would be entirely possible to convert a truck engine to run on steam using the same principals.

With regards to all the seals etc. being rotten. This may be an issue depending on where the vehicle has been, although when I worked in the aircraft restoration industry, we had a number of old WW2 parts pulled out of a lake and many of the rubber seals were still intact. Even still this isn't a huge issue: in the days before modern combustion engines were prevalent, a lot of hot air engines (like the Stirling) used leather head gaskets instead of rubber. If you ever go to an old machinery expo or a historical/vintage day at a local machinery museum, there's sure to be some of these old engines running, often hooked up to farm equipment like corn shuckers. The beauty of a steam engine over a diesel is that it doesn't need the same compression ratios; it would still run with a slight steam leak on a cylinder gasket, which might be more than enough for your survivalists.

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Short answer: no.

The problem is that steam engines are bulky and heavy. They need to carry around a lot of water in addition to fuel, their fuel isn't very energy-dense compared to hydrocarbons, and they don't use it very efficiently. A steam-powered automobile would be sluggish, have a minuscule range, and not be able to carry very much weight. Not to mention you'd have to totally replace the engine and all of its related systems - it'd be not much better than starting from scratch.

You'd be better off keeping the combustion engine and retooling it to run off of a different fuel source, such as hydrogen, ethanol, methanol, propane, or natural gas (methane). All of them provide less energy density than gasoline, and hence less range, but you may find them easier to come by in the post-apocalypse. They also have the advantage of operating on the same internal combustion principles as the engine you're starting with, which should simplify the conversion.

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    $\begingroup$ Once these post-apocalyptic guys discover the moonshine still in the back of that truck, the story goes downhill in a big way. $\endgroup$ – Willk Dec 31 '18 at 1:15
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    $\begingroup$ @Willik What kind of self-respecting post-apocalyptic guys don't have their own moonshine still? $\endgroup$ – Cadence Dec 31 '18 at 1:17
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    $\begingroup$ Actually, steam cars are not terribly sluggish, have good range and are fairly efficient and can carry typical road vehicle weight. Look up the Stanley Steamer, for example. They'd be a great post-pockyclyptic alternative! $\endgroup$ – elemtilas Dec 31 '18 at 2:16
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Yes... and no.

Could you replace the combustion engine with a steam engine? Sure. The world has seen steam engine aircraft and steam engine automobiles. There's even a modern push to reinvent the steam engine for high-efficiency automobiles. So, yes, with some ingenuity and elbow grease, you can remove an old combustion engine and replace it with a shiny new steam engine using a closed-loop water system such that it needn't be added more than periodically, as you might oil in a car today.

Your problem is fuel. You have exactly the same problem that you claim in your question: no access to petroleum. Cars aren't like trains where it's practical (if it actually was in the 1800s) to open a little door in the cab of your car and have a passenger ('cause you, the driver, need to keep both hands on the wheel) shovel coal into a firebox. From a believability standpoint, you can quite literally use any kind of engine ever considered by Humanity (e.g., diesel) — so long as you figure out how to fuel it.

So, yes, you can believably pull that truck from the mud and drop a steam engine into the vehicle. But no, it still won't work without having a tank filled with something to fuel the engine. All engines require a consummable commodity — even if it's solar power and batteries (consummable: electricity). You'll likely find that the fuel you decide on will dictate the engine you use, not the other way around.

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Theoretically, yes; practically, not much help.

If intact/not-rusted-to-junk, the pistons, cylinders and some bearings might be usable for a steam engine. See "bash valve"s for one approach: https://en.wikipedia.org/wiki/Bash_valve

However: Most of early steam engines (by mass or volume) were firebox/fire-tubes and boiler. None of the salvaged parts from your engine are much use for those critical components. Making an efficient boiler that doesn't kill its operators is far easier said than done. Similarly, having multiple pistons in precise alignment+close proximity (as in internal combustion engine blocks) isn't needed (to nearly the same degree) as a basic two-cylinder locomotive. Most of the cylinders you'd get would be too small to yield much power at pressures your boiler can deliver; consider the size of the cylinders to the rest of the locomotive here: https://www.american-rails.com/images/steam_engine_train.jpg

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While the scenario you provide isn't plausible, if a two stroke diesel engine can be found that is in good shape (i.e not degraded by corrosion or destroyed seals), then it is plausible to convert it into a "uniflow" steam engine.

The linked article covers this in more detail, but the essential understanding is the flow of the steam through the engine is reversed from the gas flow through the diesel engine. Steam is admitted through the poppet valves in the cylinder heads and exhausted through the ports in the cylinder sides.

A variety of small, uniflow steam engines are in use today, mainly converted diesel engines in rural Australia. The engines were made either by Lister or Detroit Diesel, as internal combustion 2-stroke diesels. When converted to uniflow steam operation, steam enters the cylinder via the inlet valves (formerly exhaust valves) of the Detroit Diesel 3-71 engine, while one of the cylinders is near top dead centre (TDC). The steam continues to expand after cut-off (closure of inlet valves) until the piston opens the ports at the bottom of the power stroke. Much of the spent steam goes out via the ports (exhaust ports which were formerly inlet ports). During the upstroke that follows, the remaining low pressure steam is compressed and heated, maintaining heat on top of the piston. The inlet valves open as the piston reached TDC, letting in a new charge of steam and cushioning the piston. In Australian service, efficiencies going as high as 21% have been reported for this type of single-acting uniflow steam engine. That the cranks are spaced 120-degrees apart assists in starting as well as enabling smooth power flow.

Otherwise, as many other posters pointed out, building simple steam engines from scratch ins't all that difficult. The real issue is creating a boiler which is strong and secure enough to raise high pressure steam without endangering the driver or passengers. A "flash" boiler such as those used on some 1920 era steam cars might do the trick.

In any event, all that could really be salvaged from a diesel truck would be the frame and suspension, if the engine had to be replaced. Even a truck using an adapted two cycle diesel engine would be heavily modified, the transmission, for example, would not be needed (and actually ill adapted for the torque curve of a steam engine), and room needs to be made for the boiler, water tank, condenser (if fitted) and so on.

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