Are the crappy plastic cooling systems an example of planned obsolescence?

[OnTheFence]

Was it just some idiotic design oversight?

Or was a "feature" that backfired? eg: Plastic is lighter, which means higher performance, but then you need to replace it every 80k.

Or, an intentional scam to get overly cautious yuppies to trade in the car for a new one?

[mryakan]

How is it planned obsolescence if you can replace the part and parts are aplenty?
Everything wears, there is no magic. Metal rusts, plastic cracks, life goes on.

[that318]

when the e36 was made, it wasnt expected to last as long as they did. thats why our auto tranies are sealed, and the cooling system is plastic. either way as a general maint. you should be checking and replacing things as they need to be not once they are trashed. my cousins car was still good and we just replaced everything to be safe at 125k.

[kornkid8600]

Plastics are in every car. They are just cheaper to manufacturer and they run long enough to the point where it's about expected maintenance.

[BoldUlysses]

Every engine has its weak points. Personally, I'll take a cooling system I have to keep an eye on and replace components of a little more frequently over a timing belt and clutch (Porsche 944), flaky head gasket (Toyota Supra mk3) or crankwalk (DSM) any day. Relatively speaking, BMWs are very stoutly-built cars.

[Matt Cramer]

I suspect many German engineers would consider the idea of planned obsolescence to be a professional insult. With the pace of car development these days, unplanned obsolescence is a bit enough threat as it is; you don't want to design in more of it.

When it comes to the plastic cooling system, I think BMW's engineers simply blew it (metaphorically and often literally). Modeling metal fatigue is difficult enough. Modeling how plastic deforms and changes its strength over repeated thermal cycles is as much guesswork as it is science. I believe they just plain guessed wrong. The biggest evidence that this wasn't intentional? They went back to the drawing board on just about everything but the radiator - the plastic thermostat housing and plastic water pump impeller got switched over to metal parts in mid production.

[maxell0405]

It's both planned obsolescence and under designed, but it's not a bad trade off.

Many people will fall for the "it's old and I need a new one" effect of needing a new water pump, but for the rest of us the repairs are easy and cheap. New cooling components for an e46 (non M) are less than $400 and an afternoon once every 5+ years. Big deal. If BMW had used the Stewart water pump and Zionsville aluminum radiator and expansion tank the cost would be over 3x more, up front.

For 96.7% of BMW customers that would not be worth the cost, as they are clueless about such things and look primarily at the sticker.

22.6% of those people would have bought an Audi, and 100% of those people would have been oblivious to the fact that the A4 would need a timing belt at the same age, at 3x the cost of an e46 cooling repair. Audi would have overtaken BMW in sales, management would have been ousted, the stock would have tumbled and GM would have bought BMW. OMFG, the cheap expansion tank just saved the company! Brilliant!

[OnTheFence]

Any new thoughts on this concept?

[Luftwaffe1O1]

Any new thoughts on this concept?

There are such things as cost restraints. It doesn't have to be a grand conspiracy to sell you parts, but I am sure they could put together a car that all the components last a very very long time, but there is no point, the testing and research would be aatronomical, and in the end what's the point? The length of time people keep cars these days is not as long as before. I'm sure they test and verify that the cars will hopefully at least survive without big failures in the first 100k miles.

But that's mainly because that is their timeframe of concern. No automaker has a great incentive to make sure all the little parts make it for 200k+ miles. As long as the big ticket items are ok, the little things here and there aren't worth the effort to R&D for such extensive longevity.

[MarcoZandrini]

It all comes down to cost and weight. It's much easier and cheaper to mold a piece of plastic than to bend and weld/glue/rivet metal. It saves weight, also.

[Matt Cramer]

Even if new car buyers don't hold onto cars as long, it seems people are keeping cars on the road considerably longer than before - the average age of a car registered in the US has crept up past 11 years now. So there are more age-related failures out there to report. And so far, no smoking gun memos have surfaced from BMW indicating they'd intentionally designed the plastic part to fail at a certain time.

One other thing that may be worth adding: My 1966 Dodge Dart water pump used a plastic impeller, one of the things often seems to fail on BMWs. I had to replace its water pump in 1997... because the shaft seal had started leaking. The impeller still looked perfectly fine, and I'm pretty sure it was the original water pump.

So:

1. Based on the service lifespan of plastic components in other cooling systems, it is reasonable that BMW engineers would have good reason to think that designing plastic cooling system components to last for decades is possible.

2. It is quite possible for new plastic formulations to develop problems in the field that preliminary lab testing didn't uncover.

3. Once BMW discovered these parts could prematurely fail, they redesigned the problematic parts.

So - I'm sticking with the theory that this was simply a mistake and not an intentional goal. Yes, they may have cut some corners on testing, and certainly wanted to keep low cost and light weight as a goal. But intentionally designing a plastic part to break at a specific time - rather than making something that falls into the category of, "Well, we're pretty sure it will last some time past the warranty period" - is a very risky strategy. A tiny mistake could cut your mean time to failure in half and result in a ton of warranty claims.

[Luftwaffe1O1]

Even if new car buyers don't hold onto cars as long, it seems people are keeping cars on the road considerably longer than before - the average age of a car registered in the US has crept up past 11 years now. So there are more age-related failures out there to report. And so far, no smoking gun memos have surfaced from BMW indicating they'd intentionally designed the plastic part to fail at a certain time.

One other thing that may be worth adding: My 1966 Dodge Dart water pump used a plastic impeller, one of the things often seems to fail on BMWs. I had to replace its water pump in 1997... because the shaft seal had started leaking. The impeller still looked perfectly fine, and I'm pretty sure it was the original water pump.

So:

1. Based on the service lifespan of plastic components in other cooling systems, it is reasonable that BMW engineers would have good reason to think that designing plastic cooling system components to last for decades is possible.

2. It is quite possible for new plastic formulations to develop problems in the field that preliminary lab testing didn't uncover.

3. Once BMW discovered these parts could prematurely fail, they redesigned the problematic parts.

So - I'm sticking with the theory that this was simply a mistake and not an intentional goal. Yes, they may have cut some corners on testing, and certainly wanted to keep low cost and light weight as a goal. But intentionally designing a plastic part to break at a specific time - rather than making something that falls into the category of, "Well, we're pretty sure it will last some time past the warranty period" - is a very risky strategy. A tiny mistake could cut your mean time to failure in half and result in a ton of warranty claims.

Keep in mind modern plastics are meant to degrade quicker to be safer for the environment etc, part of the reason your old dodge might have survived so long.

[MarcoZandrini]

Solution: buy a Dodge Dart with the original water pump.

[Migou]

Plastic shouldn't hold the heat as long as metal? Cheaper, less heat. I'm guessing about that. It would be lighter also.

[MassiveWalrus]

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