OldCarBum

Back when I was 17 (many years ago), I built my first Sanger flat bottom V-drive drag boat. I bought the hull bare, installed all the hardware, running gear, steering and had a 427 built for it. I dropped the motor onto the rails, stood back and thought what the hell? That's when I found out that the motors in flat bottom V-drive drag boats are installed with the flywheel forward. Ooops!!!

Crimson Thunder

The worst story I've ever heard was one of the 5.0 guys at work was finishing up his big $$$ 347 build and got the water pump bolts mixed up. He put one of the long bolts where a short bolt goes, bottomed it out, took a breaker bar and put the bolt thru the #1 (or #5 on a Ford) cylinder.

Auggievf

My biggest stupid mistake working on my '74...

I was cleaning the radiator, filling with water and cleaner, driving for a bit, and then working a bit on the engine while the radiator fluid cooled down so I could drain and repeat. After the third fill and drain I was looking at something under the hood while the engine cooled and suddenly I hear a hissing sound and my radiator cap exploded off the radiator. Scalding hot radiator fluid/cleaner shot at me but I managed to get my hand up to protect my face. My torso wasn't so lucky.... Ran inside, hurt like hell but didn't look too bad so I jumped in the cold shower to rinse off the radiator cleaner. Didn't help abate the pain which increased steadily until my wife drove me to the emergency room....

I can only assume I didn't close the cap all the way after my last fill....

mrvette

Decades ago, on a ASSfault drive I had a '70 Lemans Conv. jacked up in front as I was updating the front suspension/steering/brakes to discs.....so up high in the air on stands....summer, but not all that hot.....and so when I had the tie rod ends loose and hanging vertically, of course the car went sideways when I pushed/heaved on something, the damn ASSfault went out under both stands......bent the living EFFFFFF outta a bunch of ****, but at least it was the old ****, so I got it back up, under a new pair of heavier stands....and 3/4 plywood under the stands, flop NOW bitch......the following months saw a 5" concrete slab for a driveway there.....the ex got it in the divorce.....car ran like a charm...Great entertainment for the kids and me and g/f.......

theandies

Not on a car but my biggest dumbass mechanic story comes for general aviation. I was doing an oil change on a Cessna 152 around lunch time. In order to change small aircraft engine oil in a timely manner you run the engine up to temp to make the oil thin then drain it. I mentioned it was around lunch time so I warmed the engine up, put her back in the hangar and drained the oil while at lunch. You can probably see where this is going. I got back from lunch and already having the new oil sitting next to the plane I started pouring it in. After 4 quarts I realized I didn't put the drain plug back in and now I had 4 quarts of new oil all over the shop floor and the worst part is I had to pay for it.

BLUE1972

I agree more things than a dictionary has words.

Long funny story short - 67 Firebird - heavily worked. Ran for 2 years needed to change the carb gasket. As usual time became an issue as the Mustang we had as her car at the time decided it didn't want to start. We were supposed leave to go to a family thing at noon.
I had an after market gas peddle and cable linkage to the carb. It had a 3 holes on the carb end, first hole was return spring, second was carb stud -was held on by a C Clip -("E" - Jesus Clip) . She walks into the garage as I'm putting the bar on the carb. Rag still over the carb.
I try to jump her car - no go, starter dead - play with it - no go. Ok we will take my car.
Put the spring on, Air cleaner - starts feels better.
We drove 3 hours upstate and the car starts to slow down quickly, (on the highway). push on the gas - no response - feels the same. Sitting on the side of the highway car is idling perfect.
Pop the hood check almost everything - nothing wrong, then pull the air cleaner - linkage is laying on the manifold - never put the "C" clip back on... Replaced it and kept going. It was still laying on the manifold where I placed it .

Mod75

About 1967 i helped paint a 65 Mustang enamel baby blue after an accident, 1st time we did enamel.
One should really read the instructions and understand how to mix the contents

The paint looked great, only it took a full week to dry to the touch, at least a 100 fly's and bugs on it

derekderek

65 GTO. Ignition switch in the top left-hand corner right by the window. wanted to check if I had spark so I took out the back left plug. Hooked it to the plug wire. In the Pontiac you can look right down the spark plug hole. hold the plug on to the firewall with left hand reach my right hand in and crank the starter. just before it sparkeds I get this whole bunch of fuel air mix blows right out of the spark plug hole right past the spark plug and completely surrounds my face. Then I found out that I did have spark.

Eliredandblack

thatcorvetteguy

In auto shop there was a guy that rebuilt his 429 using gas to clean the inside of the engine. From the looks of his new after market chrome valve covers, fuel vapors and rebuilt engines are not conducive with each other. Somehow the vapors ignited blowing off the shiny new covers.

Jim71Vette

Didn't seem stupid at the time. Living in Michigan and driving to Ohio for new job until wife sold the house. One Sunday night in January '78 on I75 I hit a chunk of ice. I had cracked the peacock and a small leak developed. I got off I75 at the next exit and stopped at the first gas station I saw. The owner was just closing and said he couldn't fix anyway, but he did have a empty bay and I had some epoxy in my tool box.
Yes sir... my first Buba fix, we heated the peacock, wire brushed it and I put a gob of epoxy on it. That Buba fix never failed. I now have the radiator out but I'll have a shop check it and replace the pedcock.

Jim