Episode:  Exploding Port-a-Potty

Original Air Date: March 2, 2005

Myths: Drive Shaft Pole Vault, Exploding Port-a-Potty

The Myths..."The Mythbusters lose total control in the quest to pole vault a car with it's own drive shaft and the shocking truth of Buster's bathroom blaze in the mystery of the exploding port-a-potty. Plus Adam's childhood secret finally revealed."

DRIVE SHAFT

The myth is that a car can lose its front u-joint and the falling drive shaft can hit a hole or crack in the road, pole vaulting it end over end. Jamie Adam and Scottie set out to find a car to use, and while talking to people about the myth they find someone who pole vaulted a 1967 Plymouth Fury. Not wanting to repeat their past mistake of using the wrong type of car (American Graffiti rear axle) they set out and find an old Fury.

Now that they have the car they have to figure out a way to get the drive shaft to separate from the front u-joint. They go to the "Big Daddy of Drive Shafts," Rick Brown. He sells them the extra drive shaft for their car and suggests weakening the u-joints by cutting notches in the ears with a grinder. A teaser is shown of Jamie crashing the remote control Fury thru a chain link fence...but now itís time for the Exploding Port-a-potty.

EXPLODING  P-A-P

   Not an exploding toilet, which we all know they already did, but an exploding port-a-potty. The story goes that a man in West Virginia lit up a cigarette while inside a port-a-potty and the lighter ignited a buildup of methane produced from decomposing human waste, giving him third degree burns on part of his body. They know it exploded, but they donít believe it happened from the build up of gas from human waste. Just how will they test how much methane comes from decomposing human waste??

LITTLE MR. WHIPPLE?

At this point a little TV background about Adam and toilets goes back a little further than you might expect. They flash back to a vintage Charmin commercial, and who is that teenager with the mop of red hair? Adam, "Mr. Whipple, the roof is leaking all over the new Charmin" he excitedly exclaims.

EXPLODING P-A-P

  Back to the port-a-potty myth. For this myth they need two key elements. The first is a port-a-potty. To get one they go to port-a-potty salesman John French, who has never heard of this myth in his almost 30 years in the "business." Back at the shop Adam is bringing in key element "number 2", literally. It is his latest and grossest bodily fluid contribution. They will test the four different samples in water, urine, the blue goo (found in port-a-potties) and alone to determine the methane output. Fortunately for the viewers they use darkened flasks for the experiment. The initial tests show there are only trace amounts of methane coming from the samples, later they will see how much is present after a little decomposing.

DRIVE SHAFT

Back to the pole vaulting Fury. Now that they have the weakened drive shaft they need to control the car. For this they built their most precise remote control system to date. It controls steering, braking, acceleration and an important part, the shifter. With this built they head out to the abandoned airstrip.

As Jamie takes the Fury for a little back seat remote control spin, Tory tries to brighten the pot hole diggers day with some tricks on the bicycle they brought along. Tory's attempt to jump Adam's little red wagon ends up in embarrassing face plant on the runway as Scottie asks, "Why do I always laugh when you get hurt?" The pothole is then dug and is ready for the car, but before that we go back to the exploding port-a-potty.

EXPLODING P-A-P

The port-a-potty is prepared, holes are made in the side to feed the methane in and to exhaust the gas. When Tory reaches thru the vent hole and grabs Kari's arm we just about have more samples for the test! Tory uses the igniter from the original toilet myth and is given a wise suggestion to protect it from the blast. Kari tests the samples, but since there is no measurable amount of "natural gas" bottled methane is decided to be used. The goal is to have between 10% to 15% gas buildup in the port-a-potty to be at the explosive limits of the gas. They move out to an open area, Buster is positioned and the gas is fed in. No boom and the gas quickly dissipates. They block all the vents, pump in the gas, fire but no explosion, just a charred posterior for Buster, and Adamís ignored suggestion for protecting the igniter leaves no ignition source.

DRIVE SHAFT

As we go back to the flippin Fury, the car is rigged, the hole is dug and a safety speech is given by Jamie. His words "heavy duty killing machine" attracts Adam and he asks for a ride... Sitting in the back with no control we see Jamie lose control and send Adam over a pretty good hump and crash him thru a chain link fence. "Whoops" is right Jamie.

Time to test the myth. After more shaky test runs Jamie decides to have Adam help control the car. The weakened drive shaft is installed, the car rolls down the runway, but when it is thrown in reverse the u-joint doesnít fail. It is weakened further, but no drop. It weakened again, but no separation. After weakening it again it separates upon take off. Re-welding and then re-weakening with no separation only leads to Adamís fury. It is decided to call it a night.

EXPLODING P-A-P

Modifications are made to the port-a-potty and the igniter, still no explosion. Scottie, "Maybe it's a myth that methane is flammable." Adam, "It's not a myth, we're just idiots." A flare from the fire department is now used as an ignition source and at .9% BOOM. The door flies open. Adam states that since that earlier meter readings were 15% and the meter was low the overall concentration was too rich for explosion. A final test with a candle and no meter produces another door opening BOOM.

DRIVE SHAFT

After repeated failures to get the drive shaft to fail Jamie has an early morning brain blast and creates a threaded drive shaft that will spin itself loose when the car is put in reverse. On the first attempt after the modification the drive shaft drops on cue, but it misses the hole. Adam's "This is the one, we're gonna do it this time" is almost believable, but attempt two fails to hit the hole. Attempt 3...another miss. It is decided they are going too fast and Jamie is convinced it will work at a slower speed. Attempt number four produces a direct hit and the car's rear end jumps a few feet off the ground, but no end over end pole vault. Opening the trunk shows that they won't get a second chance since the drive shaft is sticking thru the bottom of the trunk and brake lines are severed.

RESULTS OF THE MYTHS TESTED

Exploding port-a-potty...

It is agreed that there is no way the port-a-potty could blow up from the minute gasses produced from decomposition of human waste. It is then revealed that the port-a-potty in the original myth was sitting over a leaking natural gas line and the natural gas buildup was the cause of the explosion.

MYTH BUSTED

Pole vaulting car...

Although the car did jump some when the drive shaft hit the hole it couldn't flip the car. Going faster and hitting the hole would only shove the drive shaft farther into the trunk.

MYTH BUSTED