Like for an oil pan? Or oil filter housing? That will last under the hood for 20-30 years? I guess plastic material science is pretty complex, especially with fibre additives, but probably there is a bunch of common grades that are known to last in a car and lots that don't.
What new car is built well, with metal parts?
- Thread starter ProbeGT
- Start date
The original poster is stuck on an unsophisticated understanding of the ways in which cars fail. Here are some of the issues:
1. The materials world is far more diverse than “plastics” and “metals,” which in themselves encompass many kinds of materials that have diverse properties. In many cases, the plastics are demonstrably superior.
2. The notion that cars now have worse longevity than they did in the past, and the idea that this is because of replacement of materials with plastics is doubly wrong.
3. The list of components is not really a list of common failure points.
4. While occasionally a manufacturing defect causes a plastic part to fail, the notion that parts are doomed because of cracks of failure to endure heat or heat cycles, shows lack of knowledge. Think about how much more reliable todays plastic/metal hybrid radiators are compared to the all metal rads of yore.
1. The materials world is far more diverse than “plastics” and “metals,” which in themselves encompass many kinds of materials that have diverse properties. In many cases, the plastics are demonstrably superior.
2. The notion that cars now have worse longevity than they did in the past, and the idea that this is because of replacement of materials with plastics is doubly wrong.
3. The list of components is not really a list of common failure points.
4. While occasionally a manufacturing defect causes a plastic part to fail, the notion that parts are doomed because of cracks of failure to endure heat or heat cycles, shows lack of knowledge. Think about how much more reliable todays plastic/metal hybrid radiators are compared to the all metal rads of yore.
The comment was in regards to keeping a "show car" running 80 years from now. But in short - sure you can print almost anything. There are definitely different qualities of printers. I wouldn't print a permanent part here. I might do a prototype and once confirmed its correct send the file out to a VAT printer, that can print catalyzed plastic.
Depends on the part. Oil pan is likely possible. Intake manifold, don't know. The shape would be hard.
I know in the Nissan world there is a plastic bushing on the shift cable that wears out eventually. Nissan insists on selling the whole cable for like $300. A guy on the Nissan boards figured out how to print just the little bushing. He sells them on ebay for $20. How long does it last, don't know. Probably long enough.
Meanwhile the non-plastic frame is swiss cheese after 15 years
Plastic valve covers with rubber o-ring style "gaskets" seems to be a winning combination. Definitely better than metal with a cork gasket.
Plastic intake manifolds seem to work real well. There's a few cases (ford mod engines) where they have issues. Oil filter housings .. I miss when they just screwedinto the block and that was it. Not a fan of oil coolers or sharing passages between oil/coolant for an oil filter housing.
In parts directly attached to the engine (which sees many heat cycles), metal is almost always better than plastic. This is based on years of experience wrenching. Comparing mass production cars with fighter jets is nuts. You're not getting the same exotic, lightweight materials used in a military jet on your Corolla.
My 3 current cars (in signature) were made in 2003, 2003 and 2004, respectively. All listed components on all 3 cars are 100% metal.
I have plenty of experience with 3D printing. I have designed and printed many interior trim pieces and even some functional components like plastic gears for HVAC actuators - another super common failure point where metal gears would be more appropriate. That said, 3D printing has limits and the idea that you can 3D print an intake manifold is laughable. The complexity, amount of work and prototyping required would be insane and it still wouldn't last. My entire point is, when these critical components are made from metal to begin with, you never have to worry about replacing/printing them.
With the exception of #1, what you posted is demonstrably false. To your last point, I had to replace the "hybrid" metal/plastic radiator on all 3 of my cars. What a stupid design! They always start leaking in the crimps. Complete junk. The aftermarket is flush with "all aluminum" radiator offerings which solve this problem.
I wouldn't be prototyping I would be copying, and at least you could try unlike a steel or aluminum one. I have seen more warped metal intake manifolds in my day than I have seen broken "plastic" ones. In fact, their not "plastic", there Polypropylene.
Anyway, I'll stay off your lawn.
I just had a brass radiator re-cored 2 years ago. On that same vehicle, I had to repair the intake manifold sealing surface with epoxy because it was too pitted to seal on the head.
Lat week, I replaced an aluminum thermostat housing that was too corroded to seal both on the intake manifold and the radiator hose.
Earlier this year, I replaced a stamped steel oil pan that rusted through and leaked.
Can any conclusions be drawn from those examples?
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Underpowered? What? Completely off-base there. The 2ZZ-GE engine has one of the highest specific outputs among NA mass production engines ever made. 180hp from 1.8L, that's 100 hp per liter. Except for the Honda VTEC engines, nothing comes close, bar high-end sports cars. My (sold) BMW 325i made the same 180hp from 2.5L of displacement and it felt sluggish compared to the much smaller Toyota engine.
Perhaps.
- With enough negligence and abuse, people can destroy anything.
- If you live at the bottom of the ocean or in Wisconsin, plastic may be better. For everyone else, there is metal.
Somehow I doubt these people intentionally removed and destroyed their engine parts, reassembled, then took them in for repair. But, I've been wrong before.
Never saw a plastic thermostat housing do this
Vehicles need to survive many environments. Not just yours. Nothing is perfect, but maybe the new stuff is a bit better of a compromise than the old stuff.
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I've seen countless oil pans. The rusty ones typically show signs of scraping which removes the paint and gets the corrosion process started. That's either negligence, abuse or both.
The rust belt is tough on cars for sure. I lived in NY state for 20 years and drove my 2004 Vibe GT up there for 8 years, yet, the body has virtually no rust and there is zero corrosion on any aluminum parts. Underbody washes and occasional garaging helped, I guess. Not washing salt off the car falls into the negligence category. Not changing coolant on time and allowing it to become acidic, also negligence.
Well, since most people neglect their cars just like any other appliance, it's not unreasonable that manufacturers design them with that neglect in mind, is it?
I miss the days before we had to bother with these tin-can fuel filters of today and I got to shovel coal with a big-boy steel shovel. That shovel never wore out and I never had to worry about changing a **** filter that's as weak as an empty beer can. That shovel will outlive any playskool aluminum Toyota ride that'll someday get melted down and make some other sissy modern device. **** kids.
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I have had to replace a lot of corroded parts on an engine, including the thermostat housing, on several cars.
I have not had to replace a single composite part.
Cheap plastic - like wire loom, and some electrical connectors, doesn’t hold up. I agree on that.
But properly engineered composite components are superior in many ways to their metal counterparts.
So, yeah, comparing the center barrel section of an F-18, with the oil filter housing on a Volvo is absolutely legitimate because they are both properly engineered.
And in both cases, superior to “metal.”
I have not had to replace a single composite part.
Cheap plastic - like wire loom, and some electrical connectors, doesn’t hold up. I agree on that.
But properly engineered composite components are superior in many ways to their metal counterparts.
So, yeah, comparing the center barrel section of an F-18, with the oil filter housing on a Volvo is absolutely legitimate because they are both properly engineered.
And in both cases, superior to “metal.”
I doubt volvo chose a plastic oil filter housing do to "superior" quality. It was probably cheaper to make and with good plastic, and its certainly been proven good enough. Cast aluminum still needs some machining to fit well enough, but if you asked an engineer to make a car to run for 50 years with minimal part replacement, I would think there might be more metal under the hood. An aluminum housing with a common o-ring size is more future proof, provided you don't let it corrode...
I look at my 2011 tractor and there's not much plastic, the rad ends, rad fan, light housings, dash and steering wheel and some switches, knobs on handles. Its not because of superior engineering, its just a cheap way to make a durable enough tractor. A few manufacturers have tried plastic fenders and hoods to save some money, and they get brittle and break at 10+ years which hurts sales for their new tractors. So sheet metal is the choice over a more expensive durable composite.
I think you could make a 50+ year car out of mostly composites and aluminum, but it would probably be more expensive than the sheet metal car, but to keep plastic "new" enough to act as crash structures is probably very expensive?
Cars have been on an upward reliability trajectory over the time they have been on the market. Your experience, even with three cars in a row, and your claims based on wrenching for many years are both logical fallacies. Howl at the moon as you wish, plastic, composite, ceramic and alloy components are not going anywhere and are not exacting a reliability deficit.
My recently destroyed 2009 F150 had plastic parts everywhere. They held up perfectly over 15 years.
Interestingly, my 2003 Jag X-Type has a metal intake manifold. It is leaking badly at the gasket surfaces.
