What's the worst auto fix fail you've had? I wanna know!?

I rebuilt a Volkswagen engine with the wrong parts. It was a 57 and the engine was a 63 and the parts was for a 57 lol. It ran - but not for very long.

I was working on a tractor for a friend, and I kicked over a bucket of kerosene. It spilled into my space heater and caught on fire. Before I could do anything it started the garage, then on fire the fire jumped to the house and caught it on fire.

When the fire dept got there they were putting it out and all the ammo in the back room started going off, and they backed off and let it all burn.

I had no insurance.

On top of that, the guy wanted me to pay for his tractor that was in the garage, at least it was a small one...

Top that.

I rebuilt a manual transmission on a chevy S-10 and installed it --- only to find out it was stuck in 4th gear and had no neutral. I had to take it back out and split the case again to re-align the gear synchros and linkages.

i definitely checked all 5 gear positions before putting it back in the truck the second time.....

I paid $400 for a set of "new" tires that were all worn out after 18,000 miles. Had to buy a whole new set from a reputable company, instead of the crooks who probably sold me a set of used tires.

Had to replace water pump twice due to a botched job.