What is the worst mistake you made doing your own wrenching?

Worst mistake I've made so far is recent. I'm pretty new to this, but I have some experience working with tools so I'm dangerous as hell.

Wife drives an older Mitsubishi Outlander. Pulls out of the driveway and gets to the end of the road and finds she has no power steering. Turns around, pops the hood and has a broken belt. Calls and tells me and I say, no big deal I'll get a belt on my lunch break and replace it when I get home.

Get off work at 12am and get to work on the car. I'm finding it hard to wrench the pully and get the belt in place, so I figure I'll take the tensioner pully off, set the belt and put it back on. One bolt comes out fine, but the other is really tight. I think maybe its because of the tight space I'm working in and I'm tired from work. I grab a bigger ratchet, turn hard, and it breaks loose...really loose. Fuck. I have about 5 mm of the broken off bolt sticking out now.

I've tried everything I know of besides welding a nut to it so far, and I don't have a welder. PBlaster and heating it up have done nothing. Extractor bits have broken. I'm at a loss here. Replacing the part the bolt is stuck in is $150 from Japan and involves removing a LOT of shit I am not nearly qualified to do.

Fuck.

 

I chopped the wrong leaf!

 

5K mile 'checkup'. Asked to have the oil changed - and payed for it. 16 miles later and the engine seized in rush hour traffic. Already had a lemon recall on my 2016 Taco, Toy Corp told them to "buy it back". They took the oil out, but didn't replace it. Less than 5K miles on a new 4Runner TRD OR, dealer offered a 'warranty' - I laughed, called corp number I had saved, and within an hour, had a complete refund on #2. I have the worst-good luck ever.

 

Wrong thread. Go bitch somewhere else. Be sure to mention that you have a 'turd' generation when you misuse the word 'lemon'.

 

I took off the jug on my wee old KX80 dirtbike while hunting for a water leak.
When re-installing and putting the piston back in, there was some resistance - so being a dumb 14 year old, I used an impact to suck it down the rest of the way.


That was when I learned that the piston has locating pins in the ring grooves that the split in the ring is supposed to sit on.


Oops! Scratched the hell outta my jug and had to buy a new one for $300. Had to cut a lotta frickin grass to get the cash for that one.

 

when I had my Lexus is300(about 7 years ago) I was installing lowering springs(before I got my full Coilovers setup) and my friend told me not to but the hats on the rear springs. Bolted everything up after a long day under my car in Vegas and proceeded to drive. Hit a tiny bump in the road at 35 and my rear bounced so high I felt like I caught air. It was my first time doing suspension work and I listened to my friend that said he'd "done it before." had to turn back around at 3am and fix the problem. all said and done, that easy job took me around 12 hours.

 

I built a 1776cc dual port aircooled motor for my '67 Westfalia, all new, case, crank, heads, everything. Everything except the lifters, that is. Could reuse those from the old engine.

Trouble is those reused lifters had these "elephant foot" caps on them. I knew to take them off, but left one on, fired it up, hear this "whackawhackawhacka" sound then it quiets and runs smooth.

Stared at it for a while mentally sorting through what it could be, figured it was something valve-related. I count the elephant foots I took off, came up one short. Bent valve. Only slightly though, ran fine, just a slight whackawhacka on cold startups. Also installed the distributor 180 degrees off.

I still miss that little camper, had everything, aux heater, safari windows, factory roof rack, factory awning. Sold it for $1800 a year later after it had been stolen and recovered. Naturally, I warmed it up before test drives. Yeah, yeah, shitty of me, whatever. Pro tip - don't buy a vehicle if it's been warmed up beforehand, test drive cold.

 

Punctured a fuel line on a 35 year old Toro lawnmower, I didn't think it would be as soft and rotten as it was but it definitely makes sense given the age. In school I also snapped a bolt holding a caliper onto the hub clean in half because I wasn't familiar with a non-audible torque wrench.

 

Mine is mild. I was changing the oil on my 91Toyota PU. When I screwed the new, at the time, highest dollar filter on I felt it get tight and then all of a sudden it screwed down another couple of turns easily before it tighten back up. Dumped the 5 quarts of platinum oil, cranked the thing up and instantly started hearing a loud squealing noise. I immediately shut it off, walk around to the front right passenger side and there was oil thrown all over the fence beside my truck as well as all over the wheel well. I had just moved to that area from over 2 hours away and i knew no one to give me a ride to get more oil and filter. Needless to say I was stuck there without a vehicle for about 3 days.

ETA: the seal on the new filter slipped to the side and did not seal the filter.

 

When i was 17 I was replacing the clutch on my 92 Gti after i had just rebuilt the engine. I failed to add the final 90* turn to the bolts after torquing the flexplate to the crank. It was fine for a couple weeks then i began getting a terrible rattle noise. I was lucky and i was able to just go back in and fix my mistake with no damage done.

 

the stuff nightmares are made out of.

 

I put the transmission back in my 2wd Toyota pickup without checking to see if the shift lever worked. I had to take the transmission off, fix the problem, then put it back in. It was a long night.
Rebuilt the transmission for that truck once and reused some snap rings. One broke.
Check your work along the way, don't reuse snap rings.

 

Almost 20yrs ago I built a '90 240sx, I swapped in the sr20 turbo engine from a front clip I bought from Japan. Had all the fancy bolt ons, Greddy fm intercooler, hks blow off valve, koyo aluminum radiator, tien coilovers, Cusco upper lower control arms and tie rods, many more mods, at one point I had just about every bolt out of the thing.

Long story short and don't ask why but I had the engine fan wired to a switch. Well on a really hot day in the summer I stopped at my guys auto shop to chat with him, I wasn't planning on staying long so I left it running out front and forgot to turn the fan on. About 10 minutes later I come out and the thing is over heating like hell, steaming like crazy.

I couldn't believe I did that, couple days later I wired the fan into the harness like I should have in the first place. Thought for sure I melted the head gasket but amazingly it was fine, no issues after that lol

 

You didn't read the original post did you?

https://www.tacomaworld.com/threads...ur-own-wrenching.595310/page-24#post-20953062

And that my last post was in a reply to a question I was asked. Enjoy.

 

My three most expensive screwups:

1) 17 years old, had a '73 Super Beetle. I changed the spark plugs and cross threaded one of them. I was driving down the street and heard a loud BOOM followed by the sound of a cylinder pumping away. The spark plug blew out of the cylinder head. Cost about $500 to remove the head and tap the spark plug threads.

2) 16 years old, '85 Fiero. I never checked the oil. Ended up throwing a rod. My stepdad sold it for $500. I got the Beetle next (see #1)

3) about 22 years old, '85 Corvette. I was heavy into the Corvette forum, so I got the itch to rebuild the engine and rewire the ECU and put a chip in it for more power. The engine build went fine (I ordered a short block and assembled everything in my bedroom on an engine stand). The rewiring did not.

After i installed the engine I could not get it to crank. I had my wife (girlfriend at the time) spray starting fluid into the intake while I cranked it. It ended up blowing fire back at her fortunately it just singed her arm hairs, an eye brow, and the ends of some of her long hair.

Damn car still wouldn't start.

Got deployed, wife took it to a mechanic, and $2200 later (almost all labor charges), she ran great.

 

I asked @BVita for help. Worst mistake ever.

 

Rotor and pad replacement on a 2000 C230 Kompressor. I dropped the back pad through the caliper and onto the floor. Cleaned it and placed it back in. Drove it the next day and had a horrible metallic screeching sound. At 11:30 at night, I managed to place the dropped pad in backwards. Not sure how I did not notice this on the break in process. Ceramic pads and drilled/slotted rotors.

 

Not my a vehicle, but I made a table and measured for sitting height. Completed the table in a way the legs couldn't be taken off. Then I realized I made it to stool height instead of chair height....

 

Let's see...2 incidents come to mind although I'm sure with my skills I could come up with more...

1) High school job working at a little shop doing odds and ends mechanical work. First week boss sends me to get gas for the forklift, can't find the fuel cap, only thing resembling a cap I can find is just a brass thread on cap where it seems logical for a gas tank to be. Start filling it up, after a gallon or so goes in it starts to overflow. Upon closer inspection...yup, mixed gas with the coolant. Never seen a coolant cap like that before but lesson learned.

2) Changing cam phasers on the fantastic ford 5.4 v8. Popping off the roller followers on top of the valve springs, they are going easy about halfway through until one just 'pops' and I can no longer see the valve stem. It snapped off and fell down on top of the piston...

 

I haven't made any costly mistakes in terms of $$ (not yet... knock on wood). I made one though that took a lot of time and frustration to get fixed.

I installed real locker in my Wrangler and for some reason that I still don't understand today, I pulled the handbrake at some point, before putting everything together. When I was finished, the handbrake was useless.

The fix is simple, on the internet, but even with the right tool it took me a lot of time and swear words to fix my mistake. Installing the locker was fun, fixing the brake was insane. It's always the little things in life...