Wrenching fails are the worst.
Wrenching fails are extremely annoying. You start doing something, and end up having to spend more time and money to fix it again because you broke something while working. Maybe you filled gas instead of diesel, or maybe you had to wait a week for that new oring that you broke during disassembly when you actually need your car in the morning.
Covered in this article are the top 5 wrenching fails that I have made during my mechanical career that cost me time, money, or both. When it comes to DIY Mechanics, you sometimes have to fail in order to learn. Learn from my wrenching fails.
5 – Destroyed a wishbone/front control arm in the freezing cold
I remember this like it was yesterday as it was my latest wrenching fail, but it was in reality 8 months ago. I believe it was the 28. of December 2015, and I had recently bought a beater E36 318Is. It was rusted, and came pre-dented. However, having a sound engine with 140bhp, RWD and being manual made up for all of this. The perfect car for the snowy and slippery roads of Norway.
I had recently acquired a set of steering angle increase brackets, and was eager to test them out. They work by giving 25% more steering angle when mounted. However, to mount them you are required to remove the front control arm, and the tie rod from the king pin. The tie rod came undone easily, the front control arm didn’t.
What I didn’t know, was that Norwegian salty roads make these parts rust, and melt together as if they were welded. I of course destroyed ball joint on the bearing arm in the process. I didn’t have a new ball joint at hand, but luckily I had an old bearing arm from a E36 325. The 325 bearing arm had old worn bushings, while the 318Is ones had powerflex.
Seeing what problems this caused, I simply put it all together again without mounting the steering angle bracket. All of this in the freezing cold of -10 C. Needless to say I didn’t even attempt the other side, and essentially spent the entire day ruining a good part, to mount an old worn part. It felt like the biggest waste of time ever, and the car was worse to drive afterwards.
4 – How not do to a burnout – 700$ repair
It was just a perfect time for a car entusiast. Recently turned 18, just got my license, and I had acquired the car of my dreams at the time. A manual BMW E36 325, with nearly 200bhp. I was happy.
I had seen other people doing burnouts, and I wanted to try it for myself. Cant be that hard I thought! It sure wasn’t easy, and especially not for my clutch that was swapped two weeks ago by the previous owner.
I made a few attemps at a burnout by holding the clutch in, and instantly releasing it at around 3-4000 rpm. However, I would let go partly of the throttle making the car stall every time.
It was then I got the genious idea of using all three pedals at the same time. My right foot at the throttle and brake, and left foot slowly letting the clutch out at full throttle. It sounded like it worked, but no smoke was coming from the tires and the smell of the typical burning clutch hit me. Shit. Clutch had to be changed within 50km after this, and was completely toast. I knew next to nothing about cars at the time, so a shop fixed it for me.
3 – Ruined my pressure plate – 1 week, 500$, and 4 litres of brake fluid
At the time I turned 20, I had acquired a BMW E36 M3 with the S50B32 engine. I loved it, but I also abused the hell out of it. This essentially made it so that I had to swap the clutch atleast once a year, as I also used this car for trackdays. The car had around 330 bhp, and I clutch kicked it alot in the corners. After my first drift event, a weird noise was heard from the gearbox area.
I wanted to check this noise out, so I removed the gearbox and clutch assembly. The noise came from the dual mass flywheel or clutch, and wasn’t that big of a problem so I just put it all back together. I had some troubles getting the gearbox in, but eventually got it together. However, I never got the clutch fully working after this, and it seemed to only disengage about 95%.
I spent 2-3 days trying to bleed the clutch without any luck. Then I replaced the clutch master cylinder to no effect. The clutch slave cylinder was next in line, and I even tried with a longer arm. Finally I removed the gearbox and clutch assembly, only to see that I had slightly bent one of the fingers on the pressure plate by 3-4 mm with the gearbox. Replaced the pressure plate, and it worked as intended.
I spent atleast a week doing all of this, and 500$ replacing perfectly fine parts. The worst part was the brake fluid. That shit burns, and makes your skin scratchy. Went through around 4 litres in total, as the system was bleed atleast 10 times.
2 – That time I halfed the horsepower in my BMW E36M3 S50B32 engine by tightening a bolt. 500$
Of all my wrenching fails, this is the most annoying one. Imagine the feeling you get when you ruin all of your middle torque between 1000-4500 RPM with two seconds of stupidity.
An oil spill had occurred on my engine, near a bolt that was partly unwinded. “I’ll fix that easily” I thought to myself, and tightened the bolt all the way in. Little did I know that the bolt was used to adjust the pressure within BMWs variable cam control system callos VANOS. Unwinding the bolt didn’t restore the engine power, as the part got completely broke by tightening it.
After this the engine would use more fuel, and have around half the horsepower below 4500 RPM. Fixing this cost me around 500$ in parts, and a year of research before I identified the problem. It bugged me everytime I was driving the car, knowing that performance was missing.
1 – Destroying a 2000$ E36 M3 S50B32 engine by being lazy
This is without a doubt the stupidest of all my wrenching fails. The car taxes punishes high performance car, and therefore importing a high performance version to do an engine swap is a cheaper option. I did a E36 325 -> M3 swap, and saved 21 000$ by doing so, as it would remain for tax purposes as a 325.
The only thing I didn’t do, was wiring up the oil temperature gauge that comes stock on the M3 speedometer.
Two years later, I was attending the first track meet of the year on a warm summer day in May. In preparation for this, I stayed awake for nearly 30 hours getting the car ready. New coilovers, oil change, and some bearing changes had been done to make sure everything worked perfectly. And it did, until 40 minutes had passed on the track.
The car wouldn’t drift like before, and it clearly lacked power. I slowed down some, and then I heard the noise. I immediately feared the worst, and got off track and went home. Disassembling the engine confirmed it, and the bearing had spun on two rods and damaged the crankshaft in the process. Just the parts cost me 2000$. I keep the destroyed conrod bearings as a memory, and reminder.
5 – Broke a wishbone in the dissassembly process, and replaced it with a worn one without actually mounting the intended steering increase brackets.
4 – Ruined my clutch while attempting a burnout. 700$ to repair it.
3 – Damaged the pressure plate on my gearbox, and spent an entire week fixing it while replacing parts for around 500$.
2 – Killed the performance in my engine by tightening a bolt.
1 – Literally destroyed my engine at a track day, because I was to lazy to mount an oil temperature gauge.
Of all your wrenching fails, what is your best/worst one?