Miles from home and suddenly without power steering and heat, this man had to come up with a MacGuyver-like roadside repair if he wanted to get home without a tow.

Earlier today scrolling through Reddit, I came across an ingenious roadside fix you will enjoy. This ingenious driver used a rough and ready temporary fix that got him home safe and sound without having to call AAA.

For the past six months Redditor NotThatGuyYouBanned noticed a squealing noise from his engine bay. Instead of addressing the issue or, at the very least, spraying on some belt dressing to lessen the noise, like so many car owners, he ignored it.

Deferring maintenance to another time got the best of him when the cause of his loud squealing noise, a failing idler pulley, reared its ugly head at him and gave up miles from home. The seized idler pulley also took out his serpentine belt.

Without a serpentine belt, no power is going to your water pump. Without coolant flowing through your engine, your engine cooks itself and fails in a matter of minutes.

Forgoing a tow, that’s when he employed this useful trick by first taking off his gym shorts.

I’ll let you read the rest of how he got home in his Reddit post below.

Just limped home with the cord from a pair of gym shorts running my water pump. What’s the sketchiest repair you’ve made? from r/cars

That’s right, this man took off his gym shorts and used the string that cinches up your waist as a makeshift serpentine belt.

He then re-routed his DIY serpentine belt in a way that avoids the seized idler pulley and provides power straight to the water pump.

Genius. Here’s what his fix looked like.

Share your best bush mechanic stories. Here's how I got myself home after my idler pulley failed.

When asked what kind of napkin math he used to figure out what RPM to keep his revs under, he replied with this brilliant piece of math in action.

“Well, the acceleration on the rope will be v2 /r, and I figured the pulleys were 10 and 15 cm. Given it’s a belt drive, v(linear speed, 2pi*rpm/60) will be constant for any pulley in the system, and just determined by the drive pulley. So with a 15 cm (ish) pulley, that’s 7.5cm for r, so we can plug all that in. (2pi2000/60)2 *.075= 3289.8 m/s/s of centripetal acceleration. That’s 335 g right there.

This is why belts use those pain in the a** tensioners and they’re not stretchy at all. The force on the belt can then be calculated by a simple derivation from F=ma, but to be honest I didn’t bother. As soon as I saw nearly 340 g, I figured I’d better keep it as low as I could. I figured it would be self regulating – too many revs, and the belt would lift and stall, but that could burn it out, or allow it to jump off the outer ring.

Reading that, I’m just nodding my head in agreement like, “Mhmm, those sound like plausible mathematical equations to arrive at 2,000 RPM.”

Broken serpentine belts are a common occurrence for drivers everywhere. Replacing serpentine belts can be a real chore, so we avoid it altogether until a failure, like this Redditor experienced, happens.

If you ever find yourself in a position where your serpentine belt breaks, you can’t get a tow, and need to limp home, you can use some tried-and-true emergency materials to make yourself a DIY emergency serpentine belt including but not limited to

  • Making one out of duct tape
  • Stringing together zip ties
  • Using an old belt
  • Using string from your shoe (or gym shorts)
  • Some strong panty hose

Don’t believe me? Here’s someone who used zipties to get their car’s water pump turning for a 400-mile drive home.

The best way to avoid this is to change your serpentine belt as per your car manual’s recommendation.

And what do you do with your old, but still functional serpentine belt? Well, you throw it in the back of your trunk on the off chance your belt self destructs, you can put on the old one instead of jerry rigging something out of duct tape.

Have any other ingenious methods to fix a broken serpentine belt without help? Let me know in the comments below.


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