Question of the Week: What’s the dumbest mistake you’ve made working on your car?

Back around 1974, not being able to afford the needed automatic transmission rebuild in my 1967 Ford 289 station wagon, but having the strong back and average brain of an 18 year old, I made a $100 deal + my transmission with a local wrecker for a known good tranny, as long as I pulled it myself. Along with a friend, pair of jacks, and two big tree trunk sections for jackstands, it only took the entire afternoon to get it out with no damage to ourselves or the trans. Setting it carefully next to the one we’d pulled from mine the day before, there was a really long silence. Guess a little research would have shown that due to a changeover, the '67 model year used both aluminum AND cast iron cases, and driveshafts, and other things. Oh well, I got my $100 back, and the yard got a tranny lovingly pulled for free :frowning:

I was 16, just got my license & since it was Feb in Buffalo Ny it was freezing!

I ran out of windshield washer fluid so I figured I’d throw some water mixed with antifreeze until I could get to the store & buy more.

Well the 1st time I hit “Spray” it squirted a mixture of a slimy substance all over the windshield that only got worse as the wipers smeared it all over & totally blocked any view out the windshield.
It took forever for me to drain & clear the pump & lines from the antifreeze but at least my reservoir never froze up!

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I put a new serpentine belt on a 64 Corvair engine and must have gotten the adjustment too tight. About a month later the engine started knocking bad, like I was throwing a rod. I was. The tension on the belt must have caused the outer pulley of the crankshaft vibration damper to separate from the inner, and the outer walked back into the oil filter and wore a hole through it, all the oil came out and that was the end of that Corvair for me. It was a $300 car in 1971, and I was 200 miles from home. Hitchhiking home was a lesson in humility.

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Fortunately I never paid the price for my stupidity, but as a teenager I used to get under my Mustang when it had nothing holding it up but the scissor jack that came with it. Really dumb.

Hope that the car is garaged, otherwise moisture will build up around the foam!

Been there, done that. ONCE
Always check for the old seal on the filter when I take it off.

Another incident, accidentally stepped on the edge of the drain pan after draining the oil. Pan flipped over on to my leg and foot. You can imagine the mess it made.

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Not having a cam timing belt tensioning tool when rebuilding a Lotus 2 liter engine. I had a Jensen-Healey that needed a head gasket. It took 72 nuts and bolts to get the head, intake manifold, cam housings, cam covers, etc off to the change the head gasket. I figured to leave the cam belt engaged but very slightly loose when I got it back together, and would tighten it while running to get it tight enough to not make any noise. Upon startup, it immediately skipped several teeth, and two of the 4 valves in one cylinder kissed a piston, flattening the valves and stopping the engine. I was so pissed I threw the 10mm wrench over the house.

Too many to list. Among a few of them:

  • Thought I was getting a “deal” on 20W-50 oil in the dead of winter, and using it.
  • Trying to trim the front air dam of my car with a RotoZip, instead cutting the live power cord and nearly electrocuting myself.
  • Not tightening the drain spout on the waste oil pan enough, and consequently getting a mini Exxon Valdez all over the driveway.
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I must have a million of these, too, but here’s a not so embarassing, since I was kid, one. When I was 17, in 1984, I bought my friend’s uncle’s 1967 Chevelle SS 396 4 speed for $2700. It was a nice car, but it smoked at idle bad. I found another 396 for sale in the paper, bought it, and spent a weekend pulling the original motor out and dropping in the new one, which ran great. I then sold the original motor to a Corvette guy, who needed it for his '65 Vette. He called me a few weeks later and told me whoever worked on the heads forgot to install the valve seals, and he just replaced those and the engine runs like new. I drove the Chevelle a few years and sold it to some moron who offered me a ridiculous $3950 for the car. Can’t believe my Dad let me sell it.

At age 17 my Dad and I did a full tune up on a 1972 Charger. Forgetting to install the condenser in the distributor spent next 3 days in 110 degrees trying to figure out why it wouldn’t start !!

Put the rear wheels of my low mileage/orig. ‘55 T-Bird (20 yrs. ago) up on ramps, but forgot to set the parking brake. It rolled off onto the rocker panels ($500 claim).

Several decades past I was working on the transmission linkage of my 1970 Cutlass SX. I had the Oldsmobile up on car ramps as a lift was out of the question for a newly minted 2nd class Gunners Mate. As I was young, stubborn and full of spit and vinegar, I did not chock the wheels ( mistake #1). Nor did I set the parking brake (mistake #2).
The Oldsmobile was equipped with an automatic transmission. My intended task was to tighten up the nut on the selector shaft which I had observed to be loose while performing an oil change. I gathered my tools, a 1/2” box wrench and a combination 9/16 and 1/2” open end wrench and climbed under the vehicle. I held the the shifter cable bracket with one hand and begin to tighten the nut with the wrench. All went well until the nut was tighten down.
Now he rest of this event happened much quicker than I can tell it.
As I applied the final torque to the nut the shifter bracket moved just a bit but enough that my Olds was no longer in park. There was a second of realization that I was about to be severely injured or dead. I immediately understood that if I tried to scramble out from under the car I would probably have my head crushed and be history.
I have been in dangerous occupations my entire life and have always been able to stay calm and think when in danger. So I realized that I had to stop the car from rolling before it cleared the pocket on the ramp. The only thing available to chock the wheel with was me. I quickly rolled my shoulder against the wheel nearest me. It hurt but the car stopped.
Fortunately my wife was home. I raised a shout that my neighbors heard over their TV’s. My wife came running out barely dressed. And I calmly instructed her to gently sit in the car and put it in park and tightly hold the service brake. I then removed myself from my dangerous position and talked my wife thru getting the Cutlass down of the ramps.
This is the dumbest thing I ever did. Nearly ended my young life and resulted in pain and an invaluable education. I have never used car ramps again. I always chock my wheels when using jack stands and, a few years later, saved my money and purchased a mobile four post lift that has paid for it’s self many times over. This experience made me realize that I am not immortal and that safety is always job 1. Just glad that I am here to tell this tale.

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Well this is a 2 part answer but it’s a doozy so I apologize for what’s going to be a long post.
Here goes.
I was a young buck, working as a tech at a Chevrolet dealership back in 1991 and when it was slow, we were allowed to work on whatever we wanted because we were flat rate & not getting paid when no customer cars were in the shop.

I agreed to work on a friends Corvette. He is one of those guys who notices the smallest smudge or nick and only let’s me work on his cars. And he’s a cop…
So, a simple job, he wants his differential fluid changed and drops the car off around 8 pm. (I work noon to 9) so before doing his car I had to change the u joints on my K5 Blazer.
I told my buddy “Ron” I’d do it tomorrow as he already left. So for some reason I had my advisor write a work order.
Mainly because I was leaving his car there overnight.
So before I leave I put his pristine Vette up on the lift & drain the fluid. I lock the lift & go home for the nite. Well I get in the following day at noon & replace the diff plug & remember Ron brought his own fluid. So I unlock the safetys on both lift arms ( electric Rotery lift) & proceed to lower the car to get his fluid that was in a box in the car.

So…I pull the release lever and the car starts dropping but I hear a snap & all of a sudden the car is lowering quickly on the left side & rising on the right! I’m thinking no! This can’t be happening, not to Ron’s car!!

I tried everything in the short time I had, pressing the up button, pulling the down lever, I got my arms under the car, trying to stop the inevitable.
Friends told me there was an inch of daylight between the rear liftarm & the bottom of his car just before a buddy grabbed me by my collar away from the car.

Well it lowered itself, almost gently onto it’s driver side, making a crunch as the front lift arm broke through the battery cover. Is this real llife? Yeah, it was & its Ron’s car. First thing the service Manager asks me is where’s the work order on this car? Thank God I had one, otherwise the repair would have been on me or at least Ron’s insurance co.
2 tow trucks came in and hooked lines to the wheels & in an almost ballet like maneuver, elevated the car & set it on its wheels between the 2 posts.

The damage wasn’t bad, the D/S mirror, the battery cover & battery, & 2 rims. Seeing that the rim had some minor curb rash anyhow, he was happy about those! The mirror had some scratches too so again, a win! I ended up replacing all his fluids since the car sat sideways between the lift posts for around 3 hours.
So, a bad day right? Well about 35 minutes after the car fell I hear the shop phone ring…then silence…then “Ken, phone call online 1”. I knew it was Ron & I got to tell him about his baby.
At first he didn’t believe me. Then he drove to the shop & saw for himself.
Oh, the reason for this grief? A broken stabilizer cable.
And Ron was great about it & we’re still great friends & enjoy telling this story to people all the time.
The 2nd part is shorter. I was working on a S10 on this same, but fully inspected lift a couple weeks later. I was under it adjusting the transmission shift linkage, so I was lowering it to check the alignment & raise it back up to readjust it. Those of you who have worked on these old Rotery electric lifts know that the mechanical lifts don’t reset unless you set the lift all the way to the floor, which I didn’t do because the vehicle wasn’t in park & would have rolled out of place & I’d have to reset all the lift arms. So I lift it up & I’m adjusting the linkage when I hear a SSSSSS & wonder wtf? Just as I look down to see red oil spraying over my feet, and before it computes what’s happening I get smacked in the head by the quickly lowering Blazer!
I go to run but I fall to my knees thanks to several quarts of oil on the floor, so I start crawling as quickly as I can, but not quick enough.
The truck comes down on me, but luckily it had enough ground clearance not to do any damage other than a bloody head & soiled pants. (Oil or poop, you decide.) So, after that day I sincerely had PTSD when lifting vehicles. I’d hear a creak or snap & run from under the car. Really messed with my head for a while.

Back in the 70’s I cut the molded in speaker grille out of my dash on a 1967 Olds Cutlass to install a Radio Shack wiper delay. Went further and another hole for a digital clock. Had to mount under dash speakers to replace the cut one. Those dashes are hard to find in one piece nowadays. Luckily the 67 442 that I just bought is unmolested and will stay that way.

Remembered 3 stories…

I have an affinity to over tighten things, so…

First - working on a buddy’s car I over tightened the valve cover bolt…SNAP!

Second - a couple years later, I was 20 years old, working @ a local shop which had a twin post hydraulic lift. You control said lift with your feet. Depending on the car the front bumper can be literally in your face while trying to control the lift.

Well, that info about the lift was a sidebar but I digress…

I was doing an LOF.

Drain oil, change filter, tighten drain plug, STRIP drain plug.

The boss was apoplectic.

Third - again @ the local shop, car up in the air, I’m in the middle of an LOF…it’s quitting time. Clean up and leave for the day. Come in the next morning and the front bumper of the car is ON THE GROUND, back end still 6 feet in the air!

You see, this lift had a leaking cylinder on the front post. The shop should not have had anybody using it in that condition but it was a known issue the whole 4 months I worked there. I was dumb to leave it in the air knowing what I knew…

The boss was apoplectic again.

Replacing the rear pads and rotors on my Aston-Martin DB7 V12, I didn’t notice that the torque requirements were in metric newton-meters. Set the wrench in lb-ft. Cranking the caliper bolts down, wondering just when that wrench was going to click. Hauling on it like crazy, then of course all of a sudden, wrench just spins. Wasn’t even lucky enough to shear the bolt, stripped the threads on the caliper. Replacement is absurdly expensive. Helicoil to the rescue.

@abaucom21 If there was a way to give a million thumbs up here, I would.

Especially with the rates they charge.

Almost like they are preying on people who love classics but don’t have a lot of free time or decent shop resources or both.