🔧 Salvage, Rebuild & Fuel

1. The Salvage Mindset & Priorities

Salvage is not looting — in a genuine long-term collapse it is recycling with a purpose, and in anything short of that it is theft. The legal and ethical line matters: salvage from what is truly abandoned, your own property, or with permission. That said, the skill of seeing machines as organs — motors, bearings, wire, switches, tanks — is worth building now.

Priorities change with time. In the first weeks, consumables matter most; after a year, it's rotating machinery and copper.

Rules that keep salvage useful: take the whole assembly when you can (a motor with its mount, capacitor and wiring beats a bare motor); label everything at the point of removal (masking tape + pencil); photograph or sketch before disconnecting; and store like with like — a box of mixed fasteners is a box of nothing.

2. Where to Find What — A Salvage Map

3. Safe Stripping — What Can Kill You

Slower killers to respect: asbestos (pre-1990 buildings — lagging, ceiling tiles, brake pads: wet it, don't grind it, mask up), lead (paint dust, battery paste — wash hands, no food nearby), CRT televisions (implosion hazard + charged anode), and mains feed-back — treat every wire in a building as live until you have personally proven it dead at the point of work (see the electrical safety rules in Energy §10).

4. The Salvage Toolkit

A dedicated grab-bag makes the difference between stripping a site in an hour and giving up. Build it now, keep it packed:

• Drivers & sockets: multi-bit driver (incl. Torx & security bits — appliances love them), 8–19 mm sockets + ratchet, adjustable wrench, mole grips/vice-grips.
• Cutting: hacksaw + spare blades, side cutters, cable shears, utility knife, small pry bar, cold chisel, bolt croppers if you can carry them.
• Electrical: multimeter (the single most valuable salvage tool), insulated screwdriver, electrical tape, a 10kΩ bleed resistor on leads, wire strippers.
• Handling: heavy gloves + thin mechanic's gloves, safety glasses, headtorch, masking tape + pencil (labelling), zip-lock bags for fasteners, a magnet on a string (finds steel, sorts metals).
• Fluids: penetrating oil, siphon hose, drain pan, sealable jugs — the oils and fuels you drain are salvage too.

5. What Every Machine Yields

Learn to read a dead machine as a parts list. The highest-value components, in rough order of universal usefulness:

6. Generator Maintenance

A portable generator dies from neglect far more often than from wear. The engine is a lawnmower engine; the electrical end is nearly maintenance-free. Keep the engine alive and the set lives for decades. (Deep reference: TM 5-685, bundled.)

The maintenance schedule that matters

Storage that doesn't wreck it

7. Generator Troubleshooting & Rebuild

Split every problem in two: engine side (won't start / runs badly) and electrical side (runs fine, no power out). Engine diagnosis is the spark–fuel–air–compression drill covered in Vehicles §3 — it applies unchanged.

Engine runs, no output — in order of likelihood

Diesel generator specifics

• Air in the fuel = no start. After any filter change or run-dry: crack the injector line nuts, crank until fuel weeps out clean, retighten. Most small diesels have a hand-primer pump on the filter housing — pump until firm.
• Glow plugs: hard cold-starting → test each plug for continuity; they fail one at a time.
• Water and "diesel bug": drain the water separator regularly; microbial growth in stored diesel clogs filters — treat stored fuel with biocide and keep tanks full to limit condensation (§15).
• Injectors: white smoke + knock on one cylinder → crack each injector line in turn while running; the line that makes no difference feeds the dead injector. Clean tips in solvent; replacement beats rebuilding without a pop tester.
• Diesels last. A cared-for small diesel outlives its owner: clean fuel, clean air, clean oil is 90% of it.

8. Building a Generator from a Car Alternator

Every dead car donates a 12–14 V, 40–120 A generator. Spin it fast enough and excite its field, and you have a battery charger for any 12 V bank — which through an inverter is household power.

Realistic expectations: 400–700 W continuous from a mower-engine rig — enough to charge a battery bank a few hours a day, run lights, radios and charging (see the load table in Energy). For 230/120 V AC, add an inverter sized to your loads.

9. Salvaging & Rebuilding Batteries

Batteries are the scarcest link in any post-grid power system — and the most salvageable. Two families matter: lead-acid (cars, trucks, UPS, solar banks) and lithium (laptops, power tools, e-bikes).

Lead-acid: triage first

Recovery routine: top up any low cells with distilled/rain water only (never acid — the acid never left), then charge long and slow (C/20 — e.g. 2–3 A for a car battery) for 24–48 h. If a hydrometer reads all cells within 0.030 specific gravity of each other (healthy full ≈ 1.265), it lives. A deliberate equalisation charge — controlled overcharge at ~15.5 V for 2–4 h on flooded batteries only, caps off, well ventilated — stirs stratified acid and knocks light sulfation off plates. Pulse desulfators genuinely help mildly sulfated batteries over weeks; the epsom-salt and EDTA folk remedies mostly move the problem around — try them only on batteries already destined for scrap.

Lithium: harvesting 18650s

Dead laptop packs, tool packs and e-bike batteries are mostly not dead cells — usually one bad cell group or a tripped BMS kills the pack. Inside are 18650 (or 21700) cells, the best energy storage you can salvage.

NiMH/NiCd (older tools, emergency lights): tolerant, simple to charge (C/10 for 14 h), often revivable from 0 V — worth salvaging for low-power radios and lights where lithium risk isn't wanted.

10. Making Fuel — The Honest Overview

Start with the truth: you cannot make petrol or diesel. They come from distilling crude oil (or industrial synthesis plants). What you can do is make substitutes for specific engines, and stretch what remains:

Stretching what's left: petrol keeps 6–12 months stabilised (§15); diesel keeps years if kept dry and treated. In a pinch, kerosene/heating oil/jet fuel run in most diesels with 2-stroke oil added (~1:200) for pump lubrication. Waste motor oil is not a diesel fuel for anything you care about — heavily filtered and blended it has been run in old, simple, indirect-injection engines, but it kills modern injection systems; treat it as a heating fuel instead.

11. Biodiesel from Waste Vegetable Oil

Transesterification turns used cooking oil into a genuine diesel substitute: methanol + lye split the glycerine off the oil molecules, leaving thin methyl-ester fuel. The bundled NREL Biodiesel Handling & Use Guide covers properties and engine use in depth.

Using it: Any diesel runs B100 in warm weather. Biodiesel gels sooner than diesel in cold — blend (B50 → B20) or park warm in winter, and expect it to clean old fuel systems into an early filter change. It also softens old natural-rubber fuel lines (pre-~1994 vehicles) — replace with modern hose.

12. Running Diesels on Straight Vegetable Oil

Skip the chemistry: older diesels with mechanical indirect injection (classic Mercedes 240D/300D, older tractors, listers) will burn plain vegetable oil if it's hot and thin. Cold veg oil is too thick — it coke's injectors and rings.

• Two-tank conversion (the right way): Start and shut down on diesel/biodiesel from the main tank; a second, heated tank (coolant loop through it) supplies veg oil once the engine is warm; purge back to diesel 5 minutes before shutdown so cold starts are on diesel.
• Oil prep: settle, filter to 10 µm or better, bone dry — same as biodiesel step 1.
• Which engines: mechanical inline/rotary-pump IDI engines tolerate it; common-rail and modern direct-injection engines do not — don't try.
• Blending shortcut in hot climates: 10–30% clean veg oil into diesel is usually tolerated by old IDI engines even single-tank — watch smoke and power.

13. Alcohol Fuel (Ethanol)

Ethanol is a petrol-engine fuel you can genuinely farm. The bundled DOE guide Fuel from Farms is a complete plant-scale walkthrough: feedstocks, mash, fermentation, distillation, engine use.

• The chain: starch/sugar feedstock (spoiled grain, potatoes, fruit, sugar beet) → cook & convert starches (malt or enzymes) → ferment with yeast to a ~10% "beer" → distil to 90%+ (the practical still limit is the 95.6% azeotrope) → dry further with 3A molecular sieve or parched corn if you need near-anhydrous for blending.
• Engines: Petrol engines run E10–E20 with no changes. High-percentage ethanol needs richer jetting (~30–40% larger main jet area), ethanol-proof fuel lines/seals, and a cold-start aid below ~15°C (petrol priming). Ethanol's ~30% lower energy density means more fuel per hour, but octane is excellent.
• Small-still reality: a 50 L wash at 10% yields roughly 4–5 L of usable high-proof fuel per run — meaningful for chainsaws, mowers, and generators, not for daily driving. Scale is the whole game (see the book).
• Safety: stills concentrate flammable vapour — outdoors, flame-free heat source (or well-managed), and never run one unattended. Methanol is not a by-product of clean ethanol fermentation in dangerous amounts, but the first ~50 mL "foreshots" per run taste and burn wrong — burn them as camp fuel, don't drink any of this.

14. Wood Gas for Engines

Gasifiers turn wood into engine fuel — over a million vehicles ran on wood during WWII. The full build is covered in Energy §5, and the bundled FEMA Simplified Wood Gas Generator plans give complete drawings for a unit built from a garbage can, a drum and plumbing fittings.

• Petrol engines run on 100% wood gas with a simple mixing valve at the intake — expect ~30–40% power loss and re-tuned timing.
• Diesels can't ignite wood gas alone — they dual-fuel: ~70% wood gas + ~30% diesel pilot injection, no carburettor changes.
• The catch is gas cleaning: tar and ash must be filtered (cyclone + cooler + filter) or they wreck valves — the FEMA design's filter train is the part to build carefully. And wood gas is rich in carbon monoxide: outdoor plumbing, no leaks near people.

15. Fuel Storage, Stabilising & Rotation

Core storage safety (containers, siting, quantities) is in Energy §11. The keeping-it-usable rules:

Reviving old petrol: smell (varnish = bad), look (dark/cloudy = bad). Slightly stale petrol runs blended 1:4 with fresh in tolerant engines (mowers first, never your only generator). Gummed carburettors from stale fuel are cleaned with solvent and patience — another reason to drain carbs before storage (§6).