Lead photo courtesy Alexander Kirch/Shutterstock

No matter how good of a mechanic you are, or think you are, we’ve all got a DIY fail story under our belt, so get ready for a few good laughs.

There you are in the garage getting ready to do some of the most basic maintenance to your BMW early on a Saturday morning. Starting early means you’ll be done early, and you have the rest of your day to relax or do work on the seemingly never-ending honey-do list your wife has for you. You’ve got the tools, chemicals, drain pans to make an oil change a simple 20-minute job, or so you thought.

It doesn’t take much for a simple task to turn into a headache that leaves you scratching your head wondering “How did I forget that?” I recently fell victim to this myself when changing out an air conditioning condenser that also housed the transmission cooler to my vehicle. I had to move the vehicle and upon firing it up, the fountain of transmission fluid coming from the front of the car reminded me that I forgot to reattach the cooler lines. While not funny at the time, I can now look at that stain in my driveway and remember it like it was yesterday. And so can my wife.

Knowing that I couldn’t be the only one to have moments like this, I reached out to the Bimmerfest family to see if anyone would be willing to share some of their DIY mishaps, and surprisingly enough got quite a good response. Sit back, relax, and enjoy some of our favorite contributions so hopefully you don’t make the same mistakes.

Gear Ratio Oversight
Forum member @thepontif shared an experience of a DIY upgrade gone wrong when he tried to gear up his ’99 540iT with a rear differential from a sport package model.

“I wanted to upgrade the diff to a 3.15:1 since the car didn't have a sport package. Went through the hassle lying on my driveway to get the old one out. Before I installed the replacement diff, I curiously turned the pinion yoke on the one I removed, expecting to see a little under 3 turns of the pinion for one turn of the axle shafts, as it was a 2.93:1. To my dismay, it turned a little OVER 3 turns. When I wiped away the grease and dirt from the label on the diff, it said "3.15:1." My wife was THRILLED I'd spent the day on literally nothing.
It's part of why I don't mod my cars anymore. I just got the one I really wanted, that performs the way I want, and called it done. I learned there's a limit to how much I care about cars.”

Windshield Woes
One headache led to another for forum member @rlorjr when he took on the task of replacing a leaking evaporator and expansion valve in his BMW and ended up with a cracked windshield.
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Photo courtesy of AbhishekRaj/Shutterstock

“Ha! I pulled out the front interior - center console, upper and lower dash, everything to get the whole HVAC guts out so I could replace a leaky evaporator and expansion valve. That all went great. Then I went to replace the dash pad. It just didn't seem to sit right because the glovebox wouldn't match up right. Thought maybe it needed some "persuasion". Yeah. Then there was a CRACK! That was the windshield. Pulled the dash pad out to look and wouldn't you know it slipped right down where it should have been. Anyway saved 2 Grand doing it myself but now have to pay for a new windshield! DOH! Only 4 extra screws and now I know every wire and connector under there on my e39 540 Wagon. Ready to rewire a new head unit from scratch!”

Double Whammy
When you have one DIY fail, your ego can get a little bruised. But when you have fails with two different cars, that sting is probably a little deeper. Here forum member @donato_r shares two mishaps he’s endured when working on his own vehicles.

“On my e39 540, I had a belt squeak, so I wanted to replace the belt. I got the old one off and was in the process of tightening the tensioner. The belt tensioner on the m62 has the hydraulic tensioner that’s adjustable so you must tighten a bolt to adjust it. I couldn’t get it to stay in place so i kept tightening and tightening it. Eventually I stripped the threads in the timing cover. Luckily my mechanic pulled some wizardry and fixed the issue.
My latest noteworthy one was with my e60. I wanted to change both diff fluids. To make my life easier, I wanted to put the car on truck ramps that my friend gave me. Now these ramps don’t have stops at the end (you can guess where this is going). So, I drive up and I thought I wasn’t all the way up, so I gave it some more gas. Next thing I know, i feel the car drop and then I hear a crunch. I drove off the ramps.... luckily damage was minimal. The plastic under paneling was slightly messed up, and the rocker panels popped out. I just whacked them back in and that was it. I got very lucky”

Lost and Gone Forever
DIY fails don’t always have a heavy price tag, but nonetheless can be a headache as forum member @monkeyman_69 explains about a quick trip to the local hardware store for a few missing screws.

“This story isn't at the same $ level. Recently took the driver's side knee panel to Home Depot to find some fasteners that fit. It was around 7 pm. Set the part down and walked out w/ the fasteners. 10 pm realized what I forgot. Went back at 6:30 am only to discover they compacted it w/ the other trash the night before.”

Honorable Non-BMW Mentions

Ferrari Follies

It’s always better when you can get a chuckle from someone else’s DIY fail. Forum member @Autoputzer shares a short story about a friend and his Ferrari fail.
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Photo courtesy of CyrilLutz/Shutterstock

“Not mine: A friend of mine changed the timing belt on his V12 Ferrari and got it wrong, bending all 48 valves. Determined to get back on the horse that bit him, he repaired the engine himself.”

DIY Engine Flush
As stated in my opening statement, an oil change can and should be one of the easiest maintenance things you can do at home. Forum member @Arctic Jon shares a memory from a service he did to his first car when he was in high school.

“1974. My first car in high school was a 1967 Buick Special with a V6 and three on the tree. Time to change oil. Drained the oil with my brother, and refilled. Forgot to install the drain plug. So, it dumped the oil on dad’s driveway. We cringed, and to this day, call it our 5-quart flush.”

Thank you to everyone that submitted their memorable DIY fail stories. These gave me a good laugh, and hopefully you as well; not at you, but with you. If you want to see some more memorable fail stories, all you’ve got to do is click here. If you have one that you’d like to share, please feel free to drop it in the comments.