Everybody makes mistakes, it's part of being human! Expect, when a mechanic makes a mistake, it has a tendency to be a little more costly.
Mechanics on Quora share the mistake they made that ruined someone's car. Content has been edited for clarity.
He’s Still A Client
“In about 1995, I was to do a carb overhaul on a 1985 Toyota pickup truck. A base, no-frills model with a four-speed stick trans, no a/c, plastic seats, and a 22R engine. A real plain Jane. I took the air cleaner housing off and manually set the auto choke to monitor the pull-off diaphragm when it was first started cold. Back then, there wasn’t a clutch safety switch and I didn’t realize the truck was in gear. I reached in the window after setting the choke and fast idle by hand and turned the key to start it. Well, being in gear, it took off across my shop in first gear and on fast idle. Uh oh! I grabbed the door handle and opened the door to jump in and stomp the brake pedal. And I did just that. Or so I thought. I was in a panic and with my heart pumping. There was the screeching cacophony of loud noises, and smoke all around me, and then I felt something knock me in the head. Hard. The major hit I took in the noggin was the Chrysler Lebaron convertible coming down onto the roof of the Toyota after it fell from the lift that was steadily ripping from the floor. When I came to my senses, I realized my foot was on the gas pedal rather than the brake pedal, hence the loud banging around noises. The smoke? That was the tires smoking up from doing a burnout
The truck? Well, it was totaled and about six inches shorter than stock. The Chrysler? Well, it was a convertible, so we took out the seats and several of us jumped on the floor to flatten the hump I custom made all by myself. The owner never knew anything happened because it was as good as new after our custom frame and bodywork.
The guy had his truck from day one and absolutely loved it, even though it had a gazillion miles on it. He was a big biker type ironworker that worked on nuclear plants and I’m freaked that I ruined his truck knowing how much he loved his truck and that I was half his size. He didn’t have a phone where he stayed, so I went to his house and told him the situation while groveling and apologizing profusely. I drove there with a 1987 Toyota with a/c, auto trans, new tires, and a lot fewer miles on it, I purchased from a local dealer I knew. I paid $2500 for it a half-hour after the incident and gave it to him. He was in shock and said it was all good. He was still mad though, I could sense.
A week later. I saw him coming up to my shop and my stomach knotted up fast. He wasn’t smiling. Well, when he came into my office with his wife, I thought he was going to stomp me. But, he then asked me if I remembered what I did to his truck. I of course said yes and apologized again. Profusely. He then asked me if I could do the same thing to his wife’s car since they were there to drop it off for an oil change and it was also trash. I knew then all was good between us and he’s still a client to this day. Thank God there’s no more carburetors and cars have clutch safety switches these days.”
He Wasn’t Joking
“So in 2005 I’d just got out of prison and was still looking for work. Unlike my past, this time I was determined to do the right thing and live the remainder of my life in the free world. A friend knowing my intentions let me do some work for her daughter Acura. Before going to prison, I was employed at a Honda dealership, so I know the Honda’s and Acura’s quite well. It had been almost five years since I picked up a wrench, and I was a bit rusty. Anyway, I replaced all the mounts. The rear one I had a difficult time with and had to jack the engine up a lot to install the rear mount. So after spending all day working on the car, it had just got dark and a friend who had helped me with the job and I went for a test drive.
After driving the car for about a mile, everything seemed fine, and the car ran great. So as I was driving the car back to the owner’s house, my buddy decided to turn on the stereo. You know, the ones the kids like these days with all the amps and the bass that rattles the license plate frames. So as he turned on the stereo, I noticed a small flash go off under the hood. I wasn’t sure what it was and continued driving. After about four more blocks, suddenly I start to see smoke billowing out from under the hood on the driver’s side.
So I freaked out and pulled over to the curb, thinking to myself this isn’t good. I then pulled on the hood release cable only to have the lever pretty much fall off in my hand. So now I couldn’t get the hood open. The reason is the fire that was now burning had melted the hood release cable. Now I’m in panic mode, ringing all the neighbor’s doorbells, asking if anyone had a fire extinguisher I could use. The problem was I was pretty much covered in grease and if I were in the neighbor’s shoes, I myself probably wouldn’t have opened the door either.
So at least one of the neighbors called the fire department. While all my friend and I could do was watch the car go pretty much up in flames. The fire department managed to arrive before the flames made it to the interior of the car, but at this point, it was totaled. And if it wasn’t after the fire department was done ripping the hood open and dousing the flames, it was a total loss. Needless to say, calling my friend was a phone call I hated having to make.
She answered and in her anticipation, she said, ‘Cool you’re done with the car, how long before you make it to my house so I can pay you?’
Oh, boy. After taking a deep breath, I told her I was almost there but could no longer make it. I told her, on the way there, her car caught on fire and burned to the ground.
Her response was, ‘Very funny, so when can you be here?’
Ugh, talking about wanting to crawl under a rock and hide for a year or so, Or put me back in for a year as punishment would have felt better… In any case, to make matters worse, I asked her to come to where the car was and I’d try to explain what I still really didn’t know how the fire started.
Yes, she was quite surprised to see the car. After the fire department made sure the car was a total loss, I felt like an idiot and it took my friend a while to get over it. I had no money, but I did get to pay her back by installing head gaskets on a V-8 Dodge truck she had and a few other things. The way I figured it is while lifting the engine I must have stretched one of the power cables going to the amp from the battery exposing the wire which was then laying on metal and once the stereo was turned on, poof!”
He Did Not End Up Saving Money
“Back about eight years ago, I was working for a large computer chip manufacturer as a temp, but I have always worked on cars as a hobby. About six months into my one-year assignment, I met a guy that had recently moved from his hometown, where his ex-wife and daughter lived, and all he had in his life was his VW GTI VR6. It was his pride and joy. I felt sorry for the guy because he had been unemployed for over a year. Lost everything. Had to move several states away to get a good job. When we were talking, he had mentioned he went to a repair shop, and they said he needed new brakes front and rear. I told him to come by my house on Saturday and we could do it in my garage, super easy, and it would save him like $400 over what he had quoted to do the job. I was living in an older house but had a big garage leading out to a heavily sloped driveway.
Saturday rolled around, and we put the car in the garage. I told him to put the car in first and set the parking brake so we could break loose the lug bolts. I jacked it up, removed the wheels, and disassembled everything, but when we got to the rear rotors, I realized the parking brake was still set which wouldn’t let us remove the rotors. He jumped in the car and released the parking brake. No big deal, the car was up on jack stands and had no wheels. We got everything replaced and put the wheels back on, removed the jack stands, and went inside to wash up with a job well done.
A minute later there, was a knock on the door and it was the kid from the house across the street.
‘Your car rolled out of your garage and through our garage,’ he told us. I look outside and sure enough, the VW was literally inside their garage, almost like someone had parked it there, except forgot to open the garage door first. So evidently what happened was when he had gotten in the car to release the brake, he also put the car in neutral because he thought it needed to be, even though there is no logical explanation, and we never re-set the parking brake. So after we went inside the car started rolling went down the steep driveway and across the street at the perfect angle to miss a fence and then exactly in the middle of the garage door. With the weight and momentum, it ripped the garage door off the tracks and folded it around the car, and the car came to a stop right in the middle of the garage.
The guy’s insurance covered everything, the new garage door, his new bumper and rear hatch, window, taillights, and of course repainting the back of the car. The attempt to save $400 ended up costing the guy over $1000.”
Don’t Worry, Everyone Saw That
“My dad owned a big auto body shop and when I turned 18, he sent me to the big insurance shop in Vancouver as an apprentice. Every Friday, all the cars were put in for the weekend and on Monday mornings the apprentices had to move them all out in advance of the workday. Well, one Monday morning, we went out into the shop to move the cars out for the day and I jumped into an old Ford Falcon that happened to be sitting right in front of one of the shop’s big overhead doors. So I hopped in the old girl, leaving the car door open, doing the old one-foot out and one in, on the gas and gave a couple of pumps on the accelerator then cranked it over, you know, to warm it up, before going round to open the big OH Door.
So of course the old Falcon, with the sloppy, pre-saftey-lock transmission, started up and dropped into reverse, and she did a one-wheel peel and wnt flying into – and through – the overhead door. With the car door open, it crashed against another vehicle, a freshly painted ride that was sitting beside it, bending the Falcons’ door back and ruining the entire side of that other car as well.
I managed to mash the brakes just in time to have the overhead door come crashing down, landing right on top of the car – in millions of pieces of splintered wood (it was 1980). And, as it was about ten to eight in the morning, everybody was in the coffee room right next to it. About 25 techs and managers all came streaming out to see me – with a dumb-struck and awfully surprised look on my face — as well as all the pieces of the overhead door on top of the Ford Falcon – the freshly painted ride beside it completely ruined. Needless to say, I stayed on well past midnight fixing the OH door, helping rebuild my mess, and repairing both customers’ cars before they were due for delivery.”
They’re Not Supposed To Do That
“I was a mechanic in my 20s. I worked on an awful lot of friends’ cars too. They bought parts, and drinks (or whatever), and we would work on them on the weekends, or after work.
As is with most 20-somethings, especially those already out ‘in the real world’ and not still in school, money was tight, and everyone was looking to save a buck here and there, or sometimes things happened that were just too far away from payday to be convenient.
Such was the case as happened with ‘Kim’ (not her real name). I had gone to school with Kim. However, back in High School, I was married. It was back in the 1970s.
Anyway, I hadn’t seen much of Kim since graduation. Once or twice, here and there, but hadn’t spent much time with her.
She had tracked me down through a mutual friend when her car (an old beat-up Ford Pinto), had become ‘hit and miss’ in starting. It was currently on the ‘miss’ side of the ‘hit and miss’ cycle and had refused to start that day. She hadn’t had a chance to call me yet, but she said this had given her a ‘real reason to call me,’ adding how appreciative she would be.
Ok then! I told her I would be over in a bit with cables. So I got to her place, pulled in next to her car, and got out with jumpers in hand. I told her to open the hood, as I hooked my truck’s battery up. She popped hers, I told her we’ll have to let them both sit for a bit, so her battery could charge up.
So we were standing there for a few moments and I was dazzling her with my brilliance when she looked behind me over to her engine compartment and asked, ‘Are they supposed to do that?’
I turned around, and the cables were smoking. Nope! I hooked one side up backward!
To this day, I don’t know how I did that.
Needless to say, after her main wiring harness melted clear from the Battery back, I didn’t see much of Kim anymore. The only time I saw her again was at her auto mechanic’s shop when I wrote the check to cover the 600 dollars (lots of money then) repair.”
She Still Has It To This Day
“A lady brings in her Subaru Forester for its second timing belt. She had just over 200k on it. While removing the drive belts, I notice the tensioner pulley for one of the drive belts sounded a little dry. Called her up and asked if she wanted me to replace it, no extra labor because it had to come off anyway due to doing the timing belt. Informed her it might take two to three days to get one. Being an older Subaru, the only choice was the dealership or online. Regardless, two to three days to get one. She at first says ok…
Calls me the next day and asks if it’s ok to put the car back together because now she needs it back for some kind of family thing. Don’t quite remember. I figured it had made it this long, what’s a couple more days. She picked the vehicle up and said she would return in a couple of days to get the tensioner replaced. I still promised no extra labor because she was a good customer.
So two days later, here comes the Forester on the back of a rollback. Now, as most mechanics will tell you, that’s one of the worst feelings. A vehicle you just worked on coming back ‘on the hook.’
She called me up and said it just stopped running on her. So I opened the hood and found that the tensioner had locked up, the belt slipped under the crank pulley and threw out the timing. Wow.
Removed the heads and found bent valves on one of the cylinders. So with over 200k miles, this motor is done. I felt bad, explained what happened, and she was ok with it.
Luckily, was able to work something out with the local junkyard, got her a motor with under 100k on it. Asked her if she didn’t mind paying for the motor, I would be more than happy to put it in for free. No mark-up on the motor either.
She agreed, and we still joke about it to this day. Plus, she still has that old Forester. Just won’t get rid of it.”
Always Prepare For Trips A Few Days In Advance
“I was a young apprentice, working at a repair garage. It was just before lunch, I always took off for lunch with a friend. I was hungry, as I didn’t eat breakfast.
A customer came in, just as I was getting ready to leave for lunch. He wanted an oil and filter change. Which meant grease all the fittings, check and fill oil levels in the transmission and differential. This was cutting into my lunch hour, but the boss wanted it done before I left for lunch.
I changed the oil and filter, then checked the transmission and differential oil. I took off for lunch about 45 minutes late, and the customer had immediately left on a trip hundreds of miles away. When I got back from lunch, I discovered I had left the differential fill plug out. I forgot to put it back in, after checking the oil level.
The shop tried getting hold of the vehicle owner. We wanted to have him come back, so we could replace the plug. Or get him to stop and get it replaced. Since this was long before cell phones, we tried calling his house. Spoke with his parents to let them know, hoping he would contact them.
We heard he had gotten to upper New York state before his rear end decided to blow up. I heard it happened around midnight.
The guy went out and hired an attorney when he got back from the trip. He then came to the shop. He showed the bill for repair to the owner of the shop. The shop owner, Jack, paid him on the spot for his repair. The shop admitted fault for my failure to put the oil plug back in. The shop had tried to contact him every way they knew how.
The moral of the story is, don’t wait until the last minute to take care of your car before a trip. Best to get it done a day or two before you leave. Give the shop owner the benefit of the doubt, before you decide to sue. You might just save yourself some money.
Years later, I ran into the same customer at the auto parts house. He was bad-mouthing the shop. I told him it was my fault, not the shop owner’s fault. The owner Jack paid the bill immediately, for the repair he incurred due to my mistake.”
A Valuable Lesson Was Learned
“Years ago, I used to work for the Walmart truck shop. I was doing a PM on one of their road tractors, an International cabover, with a Detroit 60 series engine. I did all the bottom end work, refilled it with about 44 quarts of oil, got in, started it up. After a few seconds, the oil pressure had not built up. I got out, looked down and about seven gallons of oil was under it.
As it turned out, in my haste to beat the clock, I had installed the oil filter with no gasket on it. It fell off at some point while installing the filter, I found it on the floor later. Very lucky for me, no damage occurred. I learned from this, now, I always look under any vehicle I change the oil in to check for leaks after an oil change, in the oil filter area.”
A Combination Of Distractions Lead To Mistakes
“I was doing an oil change on a truck with a Cummins engine, and usually when I do those, I don’t actually torque the oil plug down until the oil level is good. This particular engine wasn’t one I was familiar with, so I went online to look up its capacity. The problem was I found two different capacities, and couldn’t figure out how to tell what the difference between the two was.
I filled the engine to the lower capacity, checked the level, adjusted, checked, etc. The issue was, during this entire process, I kept being called away for various reasons. It also didn’t help I got distracted when filling it one time and went a bit over, so had to drain some oil, which normally isn’t a big deal.
But when combining the constant distraction with the atypical oil change procedure, I ended up only having the drain plug in hand tight. It came out about ten miles down the road and the engine dumped all of its oil. Luckily, Cummins engines are smart enough they actually can shut themselves down as critical conditions are detected, like no oil pressure.
On the bright side, while there didn’t actually appear to be any damage, the shop replaced all the lower end bearings, as well as had the truck towed, at no cost to the customer. They also put two people in it, so all total it only took three hours.
After that, I just took my torque wrench down into the pit with me, and any time the drain plug came out, it got torqued back in.
I’ve also seen a rebuild go bad when a piston punched its way out of the block.
We had two truck tickets get swapped, so the one that came in for engine work went to the transmission guy, and the one that needed transmission work went to the engine guy. The worst part is they both needed work from the wrong place they went, and some work somehow got approved. The shop ate almost $10,000 on that one.
Mistakes happen. Good mechanics try to make them as few and far between as possible, and good shops will do whatever they can to make it right, but it still happens. Luckily, most of them never leave the shop.”
At Least The Customer Was Happy
“The most memorable and expensive instance involved a wrench snapping and smacking the backside of the radiator. At first, I thought I had just bent a few of the fins and bloodied my knuckles. After applying the appropriate medical care, i.e., rinsing my hand off under the spigot, wrapping a bit of paper towel around my hand, and putting on fresh gloves, I returned to and completed the job.
After taking the truck around the block for a shakedown and parking it back at the shop, I got out and heard a slight hiss. As soon as I walked to the front of the truck, I could smell coolant. Smacking the radiator had caused a small fracture in one of the coolant channels.
Thankfully, it had been a short test drive, the coolant temperature was normal, and the coolant level was only slightly low. No overheat and no engine damage. I replaced the radiator at my expense and informed the customer their vehicle wouldn’t be ready until the end of the day, but they were getting a brand new all-aluminum radiator. I ended up losing about $400 on that job, but I kept the customer, and probably made my $400 back in word-of-mouth referrals.”