I've got many, here's the top two...

Back in the day, I bought a 70VW Kombi (a van with a back seat by the engine as well as center bench seat). My girlfriend, her sister and I were planning to drive to see their folks for Christmas, about a 750 mile trip from SoCal to Oregon. I'd owned bugs, never a van, but felt confident working on it. Tune-up, brakes, even adjusted the torsion tube rear suspension since it was sagging. Put a 009 distributor in it for better performance. Finished up everything just in time to leave on that long trip. Got about 450 miles when my girlfriend, who was driving, said that the engine was losing power! We pulled over, called AAA. There was a 20 car pileup somewhere and no tow trucks would be available for hours. Some very nice people took pity on us and got us off the highway. My future mother-in-law drove down 300 miles, picked us up and drove us up to OR. I came back on a Greyhound bus and met my brother, the master mechanic, with a trailer and an old Land Cruiser to tow it over the mountains to his home in Reno where we rebuilt the engine. I had burned a hole in the pistons from not having the distributor adjusted properly. That engine lasted a good long time with the stock distributor after that. Side note: The parking brake release on VW Van is a handle under the dash to the left of the steering wheel.

Page 2.

My wife (same lovely patient lady as earlier) and I bought a brand new Dodge 2500 4wd with a Cummins Diesel, and guess where we drove it a week after we brought it home... If you said Oregon give yourself a star. We needed such a beast to haul her horse trailer and we planned to have a gooseneck hitch installed once we got there. My father-in-law owns about 20 acres with gently sloping terrain. His house sits near the top of the property with a fairly long driveway running next to a fenced-in field. When we arrived and unloaded, the truck was parked in a spot near the house at the top of the driveway. The dogs were still inside the cab and my wife was using the privy giving her full view of the field. I wanted to check the fluids after such a long trip so I popped the hood. I thought. I had actually and unwittingly released the parking brake. (The hood latch on the truck is where the brake release is on the VW van. I instinctively reached for the lever that was not the brake release on the van.) I had done this standing outside the truck and already closed the door when I noticed that the front of the truck was moving towards me faster than I was walking towards it. I realized my mistake, but it was too late to catch the truck and I watched as it rolled backwards, through a barbed wire fence, missing two trees and a telephone pole before center punching a young pine tree with the rear hitch. And I do mean center punch. I couldn't have steered it and hit it so square had I tried. The bumper and hitch were trashed, and the side was scratched by barbed wire, but the frame, bed and even tailgate were untouched. The hitch took the brunt of the force and if it had hit a couple inches left or right I know the bed and/or frame would have been damaged. My wife witnessed all this from her perch on the privy and immediately (almost) came screaming out to the field. The dogs took it all in stride, but it took a long while for the sting to go away.

mine
 

Last winter I plugged in my 190d block heater draping the cord over the hood the better to see it to remind myself to unplug before driving off. Came out at night forgot the cord , drove off which snapped off my hood star. This same hood star that I had just obtained with great difficulty the week before. Bad language ensued. Now I drape the extension cord over the drivers mirror so I can't get into the car without unplugging it. Many other oopses but not too many MB related. Cheers Dan

I have many oopses over the years. Perhaps the stupidist was when I filled my Dodge with cummins up with regular......for the third time!:eek:

I couldn't figure out why, when I fired up my freshly rebuilt 240D engine, the oil pressure wouldn't come up...I had neglected to install the main oil gallery end plug:confused::eek: DOH

OH, and this one. I was redoing the interior of our 64 VW bug, Had the new carpeting for the storage area below the rear windshield spread out on my workbench. I had applied the contact cement and since I had to wait a little while, decided to light up a smoke:eek:, In a split second after striking the kitchen match under the workbench, the flames shot up to the shop rafters. If there hadn't been a fire extinguisher handy I would have been replacing more than the carpet.

First that comes to mind for me occurred while installing a new wheel bearing on a VW Caddy. I had the truck jacked up with two jackstands under the frame; when I finished, I reinstalled the wheel, jacked it back up, pulled one stand out, and pushed the other off the frame. I got up to move a few things around, and down-jacked without realizing one stand was still under the truck. That stand ruptured my fuel tank and put about 8 gallons of diesel down my driveway. I knew immediately what I had done when the truck hit the ground. All i could do as I listened to the fuel run out was walk away, straight into the house. If I'd stayed out there I would have lost my mind!

To this day, the driveway is still soft in that area. That was a good running, rust-free truck too. Wish I still had it!

Well they say 3 times is a charm - perhaps this charm would help?

http://www.dieselguard.com/

(there are loads of other products about too - this was the first hit on giggle)

Rental car places in Europe need to install these on any diesels that are going to US customers. I can't tell you how many guys I know who have mistakenly filled diesels with gasoline while renting cars in Europe. Seems like every trip we make (military visits, I mean), someone is paying to drop & drain a fuel tank. :grin:

Well it is even worse if you don't realise your mistake with a modern (euro) diesel engine and run until it splutters and dies - I've heard stories of huge repair bills like thousands and thousands 'cos the pumps are so fussy these days (I think).

This one I cant claim ,or want to .Kinda of car related .My bosses brother came down for a visit last year ,the following week when he was leaving he asked what was the fastesT way to get home to Alabama.He directed him to drive towards Houston then head east on I-10 .Well 8 hrs later they get a call that hes at a toll booth on the border of Mexico. ???

When I bought my '97 E 300 D it had only one key, the IR remote. The wife uses that so I decided to get a cheap $30 flat key for my key ring. The darned Mercedes flat key is a misshapen thing with the hole for the ring on it's side. This made the Mercedes key stick sideways when all the normal keys hung normally. I tired of being jabbed in the leg by it with the keys in my pocket, sooo... I drilled a hole for the ring through the plastic head on the key. Now the key behaved like a normal key. A few days later I decided to go fuel up the car for the wife. The darned car wouldn't start. I checked everything I could think of on the engine and could not find the problem. Then I remembered the drilled key. I got the wife's key and it started right up. That is how I figured out that there is a chip in the key.

oops
 

I sent the top rear bow lock to TOP Hydraulics to repair/replace the seal. I mounted the lock back on the cover and somehow managed to get the top lacthed and now it won't open. I am trying to force the lock open through a very small opening . OOPOOOOPPS.

I wanted to check the changeover valve for soot buildup so when I wiggle the boost line to the ALDA, the damn plastic nozzle brittle with age snapped off as I tried to remove it! :( $40 nuisance. I bypassed it for a couple of weeks but decided for calamity safety to spend the $40.

I had few in my years of wrenching...one that comes to my mind: I changed the fuel filter on my 2006 Jetta TDI. When I disassembled the fuel filter cartridge (you kinda have to tug the lid a bit to break the seal) I saw that the rubber gasket was just sitting on the top of the filter inside of the cartridge. Figured "hey, I guess thats how it supposed to be", buttoned everything back up.
Next morning about 10 minutes into my commute I see woman from the car next to me is waving and pointing somewhere toward the headlight. Got out...diesel spewing out everywhere...Shut the engine, pushed the car across 6 lanes of morning traffic (yah, NOT fun). Walked back home that 3 miles to get some tools...I could follow the trail of diesel allllll the way back to the home :rolleyes:

Reinstalled the gasket, never leaked a drop next 30,000 miles

Most recent was in February this year: did a routine oil and filter change on my transmission- put the filter and pan back on, armed with my fresh expensive synthetic fluid started putting the WHOLE 6.5 litres back in ( CAR STILL ON RAMPS UP FRONT WITH ENGINE OFF) after about 4.5 litres I heard the sound of splashing fluids hitting the garage floor. Fluid was pouring out of the transmission vents due to not following the procedure that I had done over and over before. Fill the first 4.5 litres with engine off -> start car and back off ramps-> top up the final 2 litres.

Other shocker was back in the days of carby's, and my teen years, we would find someone on a cell phone (late 1980's when only the 'yuppies' owned them) switch engine off, pump the accelerator several times, switch engine back on and BANG the excess fuel would explode and cell phone owner stunned like they were hit by lightning. One time I pumped the accelerator one too many times and blew the muffler clean off! Expensive, fun but stupid all at the same time.

old ooooops
 

A few years back, a friend bought a Dodge 1 ton for his business. It had been converted by the PO to a big block, from a sb engine.
The 383 sat crooked in the frame rails, I looked at it and noticed the motor mounts were VERY rotted, and maybe new ones would solve the problem.
The frame side mount perches have two holes drilled in each, for the different engines. Upon disassembly, I noticed the mounts were in the wrong holes, sort of a Eureka momont. Cleaned all the old grease abnd dirt off, area is assembly line spotless, installed the new mounts and took the truck for a test run, checked it, motor is crooked again.

Do I have to tell you I reinstalled the new mounts in the same wrong holes the other guy did?
(That is 5 hours I'll never get back.)