The classic 1973 GMC Motorhome had a gross, little-known option that let it spray sewage out the exhaust as you drove.

cross-posted from: https://piefed.ca/c/cars/p/506854/gmc-made-a-motorhome-that-pumped-sewage-through-its-exhaust-on-purpose

The 1973 GMC Motorhome was—and still is—a sight on the road today. This groundbreaking RV was just as interesting as its sleek body, with a V8 powering the front wheels and a spectacularly 1970s interior. And because it was the early ’70s, we had a different notion of what was okay to spray into the atmosphere as you drive. Like sewage, which an obscure option allowed this GMC to do.

One of the options available for the GMC Motorhome was a system called Thermasan, which promised to improve on one of the worst parts of RV ownership: Black water. That’s a euphemism for the raw sewage, which accumulates in an onboard tank and has to be disposed of at dumping stations. It’s as gross as it sounds, and it’s why someone at RV accessory manufacturer Thetford Corporation thought there had to be a better way. And so, the Thermasan was born.

The premise of the Thermasan “waste destruction system” was simple: Dump black water through the hot exhaust to sanitize and dispose of it. According to a maintenance manual for the 1973 model, this was done using a wiper motor-powered pump connecting the black water tank to the exhaust, where it was plumbed in just upstream of the muffler. A screen prevented solid waste from entering and clogging the system, which would’ve been hellacious to fix. Amusingly, Thetford called the exit an “ejection orifice.” The jokes write themselves.

  • Evil_Shrubbery@thelemmy.clubEnglish
    2·
    19 hours ago

    Yeah, a mixer like on boats to make everything homogeneous - and then still use the wiper pump to clean your windows, and those of everyone driving behind you.

    • DeuxChevaux@lemmy.worldEnglish
      3·
      15 hours ago

      Not sure, what the American thing was doing, but the European system would dispose of the poop very slowly, likely a litre per 100 km or so, droplet by droplet, and well burnt as long as the engine/exhaust is hot enough. I don’t think that that would do much to the environment, compared to the trains where the crapper was basically a hole in the floor. In those days, we didn’t have dump stations everywhere. Now, it would surely be unnecessary.

      • Evil_Shrubbery@thelemmy.clubEnglish
        2·
        14 hours ago

        I was just making a joke to link the septic tank to windshield washer pump directly to really mark your presence on the road and on other vehicles.