Is yanking old car parts off a junked car worthwhile? Usually not.
You've seen the ads in the Pennysaver. The local "Pick and Pull" has some new cars in! Come on down boys, and pick them apart for some good used parts!
Like the drones on the Borg Cube, many folks fall into the trap of buying used parts - picking workable parts off of wrecked or junked cars and installing them on their personal vehicles. Are used parts a good bargain? In many cases, no. And here's why.
Like used tires, used car parts may be partially worn out. As a result, all you are doing by installing used parts on your car is replacing a worn-out part with one that is just nearly worn-out. Thus, you will end up revisiting the job later on, when the nearly worn-out part you installed fails again shortly.
Now, if the parts were super-cheap or free, this might not be a bad scenario, if your time and labor is essentially worthless. But my experience with "junkyards" is that they tend to charge a lot of money for parts of questionable value.
For example, the starter motor in my truck fails. A new starter might cost on the order of $100. A rebuilt one can be had for maybe $50. The junkyard wants $25 for one out of a wrecked truck. A real bargain, right?
Well, not exactly. You see, every time you use a starter motor on your car, it wears it out a little bit. The commutator brushes (made of soft carbon) wear a little bit. The bendix mechanism wears. The pinion gear wears on the flywheel ring gear. That's how your starter failed in the first place - with the culprit most likely being the commutator brushes.
Both the new and rebuilt starters have new commutator brushes and will provide many years of good service. And the cost is not that great. The "used" one, however, has an unknown service life. If it was pulled from a late-model wreck, it may be in good shape. If it was taken from a junked car, it may be only days away from failing.
And if you factor in your time and effort, in pulling the used part off the wreck (as is the norm these days at junkyards like pick-n-pull) you are spending more time than necessary. And since the used part is not likely to last as long, if you keep the vehicle, chances are, you'll do the job again - doubling your labor.
Even the rebuilt starter will have some sort of warranty, while a used part rarely does. For most cars, the stater motor might be replaced maybe once or twice in its lifetime of 150,000 miles. If you keep throwing used starters at it, well, you might be doing this job over and over again.
And as my article about the Weibull curve notes, as a car gets older, you will have your hands full with repairs as it is, so when you do fix something, you want to make sure you are doing it right and for good. If you are doing it yourself, and saving $75 an hour on labor, why go cheap on parts?
And unfortunately, poor people fall into this trap again and again, which is why they stay poor. Joe Paycheck buys a clapped-out car near the end of its design life, and spends countless hours with it jacked up on tree-stumps in his front yard, "fixing" it. He buys used parts to "save money", but ends up wasting tons of his time. And the car is never fixed for long, as the used parts rarely last long and as the car is so worn out, something else breaks almost immediately.
So how do these used car parts places stay in business? Well, the same way casinos do. People make idiotic economic choices - look around you. People convince themselves they are getting a "bargain" at bad bargain places, and such places stay in business. Most people make horrible economic choices in life. To succeed, you need only make slightly more rational ones.
Are there times when used car parts make sense? Yes, in limited circumstances. For example, you have a car that needs a new fender, because you've smashed yours into something and you don't have collision insurance. If priced properly, a used fender could be a good bargain. If it is in a matching paint color, particularly so. Similarly, trim and interior pieces, nearly impossible to get at a dealer (for a reasonable price) might be found at a junkyard. These are parts that don't "wear out" per se.
If you are selling a car, and it needs an expensive part, like a transmission, a used one could be a good deal as well. If you are keeping the car, a used transmission from a low-miles car could be a good deal, compared to rebuilt or new.
But again, check the Weibull curve before "investing" money like that. Usually, when things like engines and transmissions go south, the car is reaching the end of its design life. Even a used transmission, with labor, could end up costing more than a car is worth. You might be better off scrapping the car (sending it to the pick and pull) than throwing another $1000 at it in repairs.
Used car parts are rarely a bargain. Fishing this far downstream rarely yields any substantial bargains. It is a lot less hassle and a lot less money and work to simply buy something newer and spend less time with dirt under your fingernails.