DIY Mechanic Mistakes

[Sodo]

They sell a special tool to twist the piston to retract it.

FYI Harbor freight has this tool. It fits about six different pistons. $6.49
Four Wheel Disc Brake Piston Tool

 

[Ken]

The thing I hate the most is dropping a bolt/nut or whatever. It is always going to land where you can't just simply pick it back up. Gonna be right in the middle under the car.
The other one is taking off an oil filter; just once I'd like to get my truck filter off without oil raining down. (Dodge with a cummins)
I will admit changing the oil in my Kioti was a breeze.:thumbsup:

cat fever My 2005 Dodge 2500 diesel was this way until I cut a door in plastic
fender on side where can just reach in remove and lift out then same to replace fill with oil and reach in and spin it on. The door is kept shut by 2 metal screws. so far no problems.
ken

 

[MNBobcat]

Just double check you have the correct new filter first, maybe even triple check.

BTDT

Crack it loose, slide a plastic bag over it and then loosen the rest of the way by hand.

 

[MNBobcat]

Just double check you have the correct new filter first, maybe even triple check.

BTDT

Crack it loose, slide a plastic bag over it and then loosen the rest of the way by hand.

 

[Oaktree]

I then started the car, backed it up and parked it to the right side of the driveway. Just as I reached for the key to shut it off I remembered that I had not added the new oil before starting and moving the car. I then had a very bad feeling that I had just made a very expensive mistake.

Along the same line, this happened to me many years ago when I was first out "on my own". Living in an rooming house I didn't have any place to change oil, so I'd go to an old abandoned sand pit and do it there, just letting the oil drain onto the ground (this was before I knew better). Oil drained, plug back in, opened the trunk to get the new oil. Guess what I'd forgotten to bring? Several mile walk on a very hot day to get to a gas station where I could buy some, then the same walk back carrying 5 quart oil cans.

Never did that again. :ashamed:

 

[Oaktree]

Was it s rear disc caliper? Maybe it was the parking (emergency/cable/manual) brake mechanism.

I ran across that once on a Suburu back in the 80s. For some reason they had the emergency brake on the front wheels, not the rear. I didn't know this. Was trying to change front pads and couldn't get the ^%$# calipers off to save my life. Finally I noticed another cable that went to the caliper, followed it and discovered that it went to the ebrake. I have no idea why they did it that way, but Suburu does a lot of weird things.

It was on this same car I learned about the threaded piston too.

 

[GreenYellow]

Along the same line, this happened to me many years ago when I was first out "on my own". Living in an rooming house I didn't have any place to change oil, so I'd go to an old abandoned sand pit and do it there, just letting the oil drain onto the ground (this was before I knew better). Oil drained, plug back in, opened the trunk to get the new oil. Guess what I'd forgotten to bring? Several mile walk on a very hot day to get to a gas station where I could buy some, then the same walk back carrying 5 quart oil cans.

Never did that again. :ashamed:

Also along the same line, when I was 16, I was changing the oil in my BRAND NEW truck. (1st or 2nd oil change) All was going fine -- except I didn't realize the rubber gasket stuck/stayed on the block when I spun the oil filter off. I screwed the new one on over it. It felt fine -- never knew it was there. When I started the truck, I heard this weird spewing/hissing sound. After about 3 seconds I shut it off to investigate. Oil had sprayed EVERYWHERE. It was like putting your thumb over the end of the water hose. 20ish PSI of oil pressure sprays WAY more oil than I would have imagined. Everything from the firewall to the radiator was dripping with oil. That was 17 years ago. I inspect the filter and side of the block every time before I put the new filter on.

Won't happen to me again.

 

[GreenYellow]

I ran across that once on a Suburu back in the 80s. For some reason they had the emergency brake on the front wheels, not the rear. I didn't know this. Was trying to change front pads and couldn't get the ^%$# calipers off to save my life. Finally I noticed another cable that went to the caliper, followed it and discovered that it went to the ebrake. I have no idea why they did it that way, but Suburu does a lot of weird things.

It was on this same car I learned about the threaded piston too.

Been there, Oaktree! Not on the front, but on the rear. Was changing brakes on the back of my wife's car a couple years ago. She parked it by my shop as I asked her to. She NEVER sets the e brake, but did this time since she knew I'd be jacking it up. I worked myself to death (and called it a few names) trying to get everything undone. After 20-30 minutes, it finally dawned on me... Felt like a total dufas. Wife got a good laugh when broke the news...

 

[Sodo]

Not sure if I'd classify alot of them as mistakes in the sense of a rookie or diyer screwing up. A lot of things on the list are unavoidable from time to time.

Being a mechanic by trade, stripped and broken bolts are unavoidable. And I am sure EVERYTHING is engineered with a torque spec. But I can assure u I don't carry around a torque wrench on my cart at work. And we have all had our share of burning chemicals in a cut. And I am guilty of not always using a special tool when the mfg requires. I improvise and usually make something that will work.

Agreed. This list was created by a "mechanic" who hasn't "been around the block." As this person progresses in experience I believe every one of his "no-nos" will become a "maybe", and some of them will become "seldoms".

If anybody out there wants to really add to his/her mechanikking by info on the internet there must be better lists than this, made by true mechanics. Problem is, to get to experience, you have to start with ground rules then learn HOW the rules are broken.

 

[JohnMacca]

Along the same line, this happened to me many years ago when I was first out "on my own". Living in an rooming house I didn't have any place to change oil, so I'd go to an old abandoned sand pit and do it there, just letting the oil drain onto the ground (this was before I knew better). Oil drained, plug back in, opened the trunk to get the new oil. Guess what I'd forgotten to bring? Several mile walk on a very hot day to get to a gas station where I could buy some, then the same walk back carrying 5 quart oil cans.

Never did that again. :ashamed:

I heard a similar story about a bloke I know. His method of changing the oil in his car was to drive out of town to a quiet bush track and dump the oil on the ground. (Even 20 - 30 years ago every one told him he was d***head for dumping oil like that).

So, one time he is out with his wife on a day trip and decides to do the bush detour oil change on the way home. He pulls up, crawls under the car and removes the drain plug. He then leisurely gets the oil out of the back of the car and then reaches in and pulls on the hood release to remove the filler cap to help drain the last of the oil.

The cable breaks off at the latch. Big "Oh s**t" moment and he flies back underneath to try and put the plug back in ... too late.

He then spends a couple of hours trying to hit the latch in the right spot with a stick, and finally gets the hood up and the oil in.

The wife was sworn to secrecy, but she was so cheesed off that she tells the story now to everyone to name and shame him on the oil dumping. (Far as I know that was the last time).

 

[JohnMacca]

Along the same line, this happened to me many years ago when I was first out "on my own". Living in an rooming house I didn't have any place to change oil, so I'd go to an old abandoned sand pit and do it there, just letting the oil drain onto the ground (this was before I knew better). Oil drained, plug back in, opened the trunk to get the new oil. Guess what I'd forgotten to bring? Several mile walk on a very hot day to get to a gas station where I could buy some, then the same walk back carrying 5 quart oil cans.

Never did that again. :ashamed:

I heard a similar story about a bloke I know. His method of changing the oil in his car was to drive out of town to a quiet bush track and dump the oil on the ground. (Even 20 - 30 years ago every one told him he was d***head for dumping oil like that).

So, one time he is out with his wife on a day trip and decides to do the bush detour oil change on the way home. He pulls up, crawls under the car and removes the drain plug. He then leisurely gets the oil out of the back of the car and then reaches in and pulls on the hood release to remove the filler cap to help drain the last of the oil.

The cable breaks off at the latch. Big "Oh s**t" moment and he flies back underneath to try and put the plug back in ... too late.

He then spends a couple of hours trying to hit the latch in the right spot with a stick, and finally gets the hood up and the oil in.

The wife was sworn to secrecy, but she was so cheesed off that she tells the story now to everyone to name and shame him on the oil dumping. (Far as I know that was the last time).

 

[ecbaatz]

Any disc brake that has a cable parking brake must be turned to re-set the auto adjuster for the parking brake.

Did not on my 1999 F150 with rear disc brakes.

 

[Winmac]

That's because You have a disc/ drum combination, the parking brake is not on the disc.

Guess there's always an exception to any general rule

 

[mark02tj]

This was not MY mistake, but I was the one that found it....

Back when I was in high school and college I worked as a small engine mechanic (mowers, tillers, etc.). One day this very nice lady brought in her Toro push mower. She said that her husband had worked on it and it "almost would start" but he couldn't get it going. I pulled it through a couple of times to see what it would do. Weak spark and the plug was bone dry. I recommended a tune up (points, condenser, carb rebuild, lap valves, etc.). I told her it would be about $60. She called her husband who gave the go ahead but we were told to keep all the parts because he wanted to see them!!

Got around to doing the tune up a few days later. Popped the flywheel to do the points. Pulled the head and then pulled the carb off. THERE was the problem!! Her genius husband had also pulled the carb and torn up the intake gasket (very common!) in the process. Instead of stopping in and spending $0.27 (yup, that was the price on it back then) on a new gasket, he decided to make his own out of some sort of thin cardboard like from the back of a spiral binder. He did a great job tracing the outline and placing the bolt holes but Einstein forgot to cut the hole in the middle so the fuel could pass through it!! :laughing: Shop owner and I got a good chuckle out of it and I went ahead and finished up the tune-up and bagged all the old parts, including the home made gasket.

Called the lady and she came to get it. I went over each part with her and explained what it was for. I pulled the homemade gasket out of the bag and told her "here was a major problem!" and explained what he'd done. She replied that "he's going to be soooo embarrassed when I show him this." She's happy, pays the bill and I load the mower for her. An hour or so later her husband calls and he's not embarrassed - he's super mad!! Yelled at me for not calling him the moment that I found the gasket. I explained to him that he'd approved a tune-up, the mower needed the tune-up and that the carb was the last thing that I'd pulled from the engine anyway, so he'd have the same amount of labor anyway as well as most of the parts since the points were burnt and you can't reuse things like head gaskets. Still not happy. Oh well. That was 30 years ago and I still think about that ya-hoo anytime I pull a small engine apart! :laughing:

 

[KennyG]

A couple of crazy things that happened years ago with a Yamaha RD350. I bought it used and went into the dealer and bought a set of spark plugs. A bit later I pulled the heads to scrape the carbon off and found the piston heads starting to sag on the way to a hole. Turns out the parts guy sold me plugs several steps too hot. Trust but Verify? The dealer offered me free replacement plugs. I was not impressed.

I rebuilt the engine myself and couldn't get it to run smooth and it was fouling the correct plugs. After a lot of frustration, I found out the slides in a Mikuni carb can be rotated 180 degrees and still fit perfectly. Who would have thought?

 

[MossRoad]

Who would have thought?

Me! I did the same thing on my RD400! :laughing:

 

[farm boy00]

I pulled the old coil off my old Briggs once. Put the new one on and got little spark. I even posted a thread on here and someone pointed out it was upside. Flipped and it fired instantly!! Days and days of scratching my head and my dad the same

 

[Industrial Toys]

I seem to enjoy spraying brake cleaner in my eyes as I have done it a few times now! Can't be the good stuff of old, as it didn't hurt my contacts one bit and heck, I can still see.