When have you blamed your lack of mechanical skills only to find out the parts/car were defective?

So I l just finished installing the boost gauge on my 06 mustang.  I had the wires and tubing for the gauges for like three years.  It was either too nice to be inside or not autocross, or too cold to work in the garage.  I decided I would at least tackle the  boost gauge and not finish my day without it installed.

I won't go into all the issues I had installing it, (can't see up close anymore, didn't like the ground, made my own but couldn't find drivers, bolts, etc)  it didn't go smoothly.

The big snag came when the gauge wouldn't fit in the pod.  Stopped halfway through.  I assumed it was the line kinking, or I had too much leftover wiring in the pod.  I also thought I had waited so long that the boost line had become too brittle to bend.

Off to the speed shop for new line.  Re installed everything only to find that the gauge wouldn't fit in the pod.

On closer inspection, one of the grommets holding the pod in wasn't sunk enough, so it was catching the gauge housing. Dremel too to the rescue!

This made me realize that I'm not always the worst mechanic I know.  Although I am far from good.

I have been sold the wrong bake pads, calipers that were machined wrong, fittings that were welded that should not have been.  For a while I felt like my local NAPA had it in for me.

But today, 2.5 hours at least were added to my project, by a defect and not my defective skills.  

Who else has had this happen? 

Dude, I've been a professional mechanic, or technician, or whatever the hell since 1980.  They haven't invented a number big enough to count the times.

However, you can limit your exposure by never using aftermarket electronics, always buying your Asian cars brake parts at the dealers, and understanding that the word "Universal" actually means, "This fits nothing in the universe without modification, and you might well break it trying to fit it in the hole we drilled."

And don't ever fix British cars with reproduction parts.

Spent the better part of two years trying to fix my Tiburon. Intermittent dying, then died completely. Knew right away it was the fuel pump. Quick fix. Except it didn’t. I was at a loss. Tried timing (maybe belt skipped?), read about chafed wiring harness, nope. Full tune up, nope. Gave up. Started again. Gave up again.

Finally gave in and let my mechanic take a shot at it. BAD FUEL PUMP right out of the box. I was too naive to realize a new part could be bad while still in the box. I won’t be making that mistake again.  

"NEW means Never Ever Worked".

This is why I am very strict about proper diagnosis instead of throwing parts at it.  Because the old part might not have been bad, but the new part is, and now you have two problems.  (See also:  My GTI, which had something like five problems keeping it from running, four of which were defective or poorly installed new parts)

Twice I've bought defective car batteries that caused a litany of difficult to explain problems.  Now I always (try to remember to) have the store test before purchasing.

Happened a lot more than I'd like as a professional mechanic.

Doing stuff at home it's always a freaking master cylinder. I'm not sure why they're so hard to produce or reman but the Vibe is on its 3rd in 1.5 years and the current one is partially bypassing.

Racecar wasn't charging. Had the alternator tested and sure enough it was bad. Replaced the alternator. Still wasn't charging. The hell... 

One of my teammates now has replacement alternators tested upon purchase.

More times than I can count. The worst one was an alternator too. Except this was in an '00 Audi A6 Avant. One of the most difficult alternator R&R's I've ever experienced and I had not one but two bad alternators from my local pro-parts house. I ended up getting my core back and taking it to a local rebuilder. I don't get remanufactured alternators if I can avoid it and if I can't I get 'em tested before I leave the store.

Streetwiseguy said:

 

And don't ever fix British cars with reproduction parts.

Some of the restoration parts for my bugeye have been laughably terrible.

Brake masters are surprisingly easy to mess up aparrently, Ford's had a bunch recalled.

302 Ford. I had done a couple of engine swaps and changed out the head gaskets a couple of times. This time, I just couldn't get it to fire.

Obviously, it was Ford's fault for having the distributor turn the opposite direction than what I remembered.

I ended up paying for a tow and an hour of shop time to have someone switch the wires around.

Not really in the spirit of this discussion, couldn't blame anyone but myself. On that day, it was all my lack of skill.

5 years chasing driveline vibration, only to discover the culprit was my custom-made driveshaft.

Defective subaru water pump, replaced the radiator and head gaskets before pulling the new pump and finding a non attached impeller. Wil NEVER trust advanced auto parts again.

At least 2 brake master cyls that were dead in the the box on arrival, many slave cyls, a starter motor, a new supposedly not remanned brake caliper that started bleeding fluid before we even started applying brake pedal, and my favorite, an adapter plate that required us to sawzall the startermotor section off and reweld it to move the starter inward close enough to actually engage the flywheel ring gear. 

And many, many others that I'm sure I've forgotten out of sanity preservation. 

In reply to Apexcarver :

One of my semi-recent favorites was the replacement head studs from Vicky B. Nothing like a stud that's supposed to be torqued to 55# snapping @ 40#. Customer service was good but I got new studs elsewhere.

The last starter I purchased was new OEM Ford unit because of 50 years experience with defective rebuilt/remanufactured starters and alternators. Back in the day, we used to rebuild these units with greater success. 

Parts quality has gone downhill in the last 20 to 30 years.

Does this count, even though the new part was good? 

97 Expedition had starting issues. First time it wouldn't start, I hit it with jumper cables and it started right up. Hmm, time for a new battery (it was seven years old, anyhow). Started fine... for a while. Jumper cables didn't start it, this time. Hmm, time for a new starter. Started fine... for a while. Dafuq? Had starter, battery and alternator tested; all good. 

Poked around under the truck for a couple hours, and found that the main starter cable was crumbling inside the insulation, about 3" from the starter lug, and I didn't notice it. After replacing the cable, it never had a problem starting again. Doh! 

Regarding Asian break parts. There's a Scion taking up space in my garage because both of the parts house brand wheel cylinders I got were defective. One had the mounting bolt hole drilled wrong, the 2nd had the bleed screw threads stripped. (We did both sides but got lucky on the other side) 

Also the 3rd gen f-body aftermarket speed parts rabbit hole of nothing bolting on ever. 

Nearly all the times I have installed something from rockauto other thank brakes.

In reply to Daylan C :

Oh no, it's not just F-body.  Aftermarket speed parts so very rarely work without having to modify or adapt or something that it is notable when something just bolts in without extra work (Magnusson superchargers being at the top of this unfortunately very short list)

I could name a Major Bellhousing Manufacturer who, to date, has yet to ship me a bellhousing that didn't need to be machined parallel.  My favorite was the Ford bellhousing with the starter pocket in the wrong place, dowel locations in the wrong place (had to put offset dowels in just to bolt it to the block so I could find how far off the center was!), and my favorite part was the SFI sticker had a date of manufacture that was over a year away from when the part had shipped to us from a third party vendor.  (Although maybe they invented time travel so they could make parts after they had been ordered?  That'd be one hell of a good way to manage production)

Knurled. said:

In reply to Daylan C :

Oh no, it's not just F-body.  Aftermarket speed parts so very rarely work without having to modify or adapt or something that it is notable when something just bolts in without extra work (Magnusson superchargers being at the top of this unfortunately very short list)

 

 

Interesting.  I haven't had this issue with aftermarket parts from more respectable brands.  Megan racing?  Sure, I expect something not to fit.

The thing that shocks me is when a part is made by the hundreds of thousands (millions?) and distributed by a nationwide auto parts chain and it doesn't fit.  Is it not even worth the effort to check a part before producting that many of them?

In reply to Knurled. :

I'm thinking of a set of S&W subframe connectors and trans crossmember. None of the wholes were even remotely right. We had to slot all the holes and add washers. It actually would have been preferable if they hadn't bothered drilling holes.

Daylan C said:

In reply to Knurled. :

I'm thinking of a set of S&W subframe connectors and trans crossmember. None of the wholes were even remotely right. We had to slot all the holes and add washers. It actually would have been preferable if they hadn't bothered drilling holes.

That is completely normal and, to be honest, not entirely their fault.  There's a good amount of production line tolerance, and there is a very strong chance that the car that they used to develop the product is wildly different from your car.  That is even before factoring in chassis sag/flex/bending/warpage/etc.

Not a GM, but IIRC the production tolerances on a Fox-body could stack one way or the other to add up to a whole inch difference in length!

edit - I also recall that by the end of the production run, the body stamping dies were so worn that GM opted to use structural adhesive in addition to spot welding on '92s, maybe '91s as well.  Now imagine you have one of these late cars, and you're using parts developed on a brand new '82...

In reply to Knurled. :

I honestly kind of expected it. It was still a fair bit if an inconvenience at the time. I'm sure if I tried to put the same part number on my '87 Trans Am they would fit differently than they did on my friend's '92 Camaro. And I don't trust the chassis to be accurate to factory dimensions on either of our cars. His has evidence of being jacked up at way wrong points and probably other abuse. Mine was covered in aftermarket parts but had no SFCs on it. So it was probably driven fairly hard and things have tweaked over the years. (Cracked paint on the roof being evidence of chassis flex).

I do know our other friend with the Fox body seems to suggest he doesn't have as much headache with his car. I don't believe him.

EDIT responding to your edit: actually the car I was thinking of is a '92 so yeah that's definitely a solid point.

EDIT2: also ignoring when you're mixing parts from different manufacturers. Like Hedman probably didn't mockup their Y pipe on a car with those same S&W SFCs. So of course they want to be in the same place when both installed at the same time. And so the y pipe needs to he shortened. And then the SLP muffler you decided to mount where the cats used to live still doesn't have enough room so it hits the connector when you're on the throttle. 

I had an 89 crown vic, horrible piece of trash.  I shot a screw into the gas tank because who puts a gas tank right up against the front wall of the trunk where someone would screw an amp?   So i put some silicone on the screw and put it back in and never installed the amp. 

Anyway it died.  Battery charged and tested good so i pulled the alternator.  Took it in and they tested it and said it was good, put back on and it died again the next day.  Couldn’t figure it out and this was pre zomg everything is online days, so parked it.  6 months later i finally found someone that told me the voltage regulator is bypassed in the parts store machine test of that particular alternator, and so the regulator can be dead but they still show charge.  One $28ish regulator later the car was fixed and i sold it to some other poor soul.

Back in 2007ish I was driving my 97 Explorer to the golf course when the serpentine belt tensioner seized and sheared without warning.  Taking out the belt and losing all accessory drive.  Immediately pulled off somewhere out of traffic and called for someone to bring me tools.  Vatozone had an idler pulley and a new belt (yay) in stock (double yay).  So back to the truck and I bolted in the pulley and spent the next hour or more wrestling the belt in 95 degree heat.  Finally gave up and caught another ride back to the 'zone where I waited in line to explain to the parts monkey that they had sold me the wrong part.

He looked it up and sure enough the belt box was the correct one for my Exploader......but the belt was indeed wrong.  And 6" too short.  CORRECT belt in hand the installation took 2 minutes.

I never made it to the golf course.