Fridge Compressor to 2-Stroke Engine: JB Weld for the Win

We like this one because it has a real Junkyard Wars feel to it: turning a cast-off fridge compressor into a two-stroke internal combustion engine. [Makerj101] is doing this with tooling no more complicated than a hacksaw and a hand drill. And JB Weld — lots and lots of JB Weld.

[Makerj101]’s video series takes us through his entire conversion process. Despite the outward similarity between compressors and engines, there are enough crucial differences to make the conversion challenging. A scheme for controlling intake and exhaust had to be implemented, the crankcase needed to be sealed, and a cylinder head with a spark plug needed to be fabricated. All of these steps would have been trivial in a machine shop with mill and lathe, but [Makerj101] chose the hard way. An old CPU heat sink serves as a cylinder head, copper wire forms a head gasket and spacer to decrease the compression ratio, and the old motor rotor serves as a flywheel. JB Weld is slathered everywhere, and to good effect as the test run in the video below shows.

Think you recognize [Makerj101]? You probably do, since we featured his previous machine shop-less engine build. This guy sure gets his money’s worth out of a tube of JB Weld.

Thanks to [Gregg Eshelman] for the tip.

25 thoughts on “Fridge Compressor to 2-Stroke Engine: JB Weld for the Win

    1. It is also known as JB weld in the UK and usually only found in some of those backstreet pound-stretch shops,
      The most common type being it contains metal particles (notably iron).

      The decent (long cure time stuff) can handle (and in thin enough layers:transfer) High temperatures, it makes good potting compound in a pinch, though make sure you pre-coat circuits in another epoxy as the iron has a capacitive impedance on high frequency devices.

      Only recently… and via Hack-A-Day, have I found out just how strong this stuff is: Engine repair/construction with this stuff, now I’ve seen it all ;-) (in good jest)

      1. For us non-UK-types, what is a “backstreet pound-stretch shop”?
        I keep saying that if we’d lost The War back in 1776, we’d all be speaking English today.
        […sounds like a seedy place for torturing overweight miscreants…]

    2. Look up Araldite. That’s a line of epoxies with some similar to JB Weld. There’s also Loctite Epoxy Weld.

      I repaired a pinhole in a car air conditioning condenser with the slow set version of JB Weld. I put it on, let it set until it started to gel, then pulled a partial vacuum in the system and let it sit overnight. Next day I put the vacuum pump on it for a couple of hours, charged it up and the AC worked fine the rest of the time I owned the car.

  1. JB Weld just continues to amaze and exceed every reasonable expectation.

    People need to start thinking about JB Weld like the people making Micarta do. You get epoxy and mix it with cloth, paper or whatever and get Micarta. So take epoxy and mix it with metal powder, steel wool, metal screen, who knows. There may be a world of new possibilities here.

    1. Disclaimer: I know very little about the subject–
      What I think I know is that a diesel engine of any sex–2 cycle or 4 cycle–requires poppet valves. I think. Perhaps.

      “It ain’t what you don’t know that gets you in trouble; it’s what you do know that ain’t so.”–Will Rogers. The Artful Dodger. et al.

    1. It depends on the plastic. If you’re trying to stick food safe plastics together, they’re a tough nut. That’s because those are usually highly non-polar so they don’t interact much with anything.

      In recent years adhesives have been made that will stick to the formerly unstickable polyetheylene and polypropylene based plastics. That took some serious chemistry wizardry to figure out ways to stick things together that didn’t involve chemical dissolving or electron valence bonding, neither of which works very well, if at all, on non-polar plastics.

      Polar plastics have molecules with “free” spaces for electrons in their most accessible atoms. Glues with the right complimentary electron arrangement will adhere very strongly to those plastics, without using solvents to partially melt the surface. Slop that on a polywhatever surface and it’ll slide off.

      PETG as used in most carbonated beverage bottles is difficult to get stuff to stick to, but I accidentally found that Smooth-On’s Smooth-Cast 320Q can. 320Q is water thin and has a 30 second pot life. It ‘kicks’ hard and goes solid FAST, with plenty of heat. I spilled some mixed 320Q on a polypropylene table and it ran around a PETG bottle I use to mix one of my colored resins. Before I could think about cleanup, the bottle was stuck to the table. A strong tug popped it loose, leaving a clean patch on the table. But there’s still pieces of 320Q stuck fast to the bottom of the bottle after a few years.

  2. He should re-attach the stator coils of the motor and try to use them as an asynchronous generator with an excitation capacitor. perhaps it is even possible to use the start winding or a combination of capacitors on both windings for a more stable voltage.

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