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Comment by jacquesm | Hacker News Reader

The main reason why MB lasts so long is due to a single component in the engine, they still use a chain rather than a timing belt. This one little change has so much impact on the rest of the engine design that they tend to last very long compared to cars that have timing belts. Suddenly a whole pile of stuff is happening inside the engine enclosure instead of outside of it reducing the number of seals and in general reducing complexity outside of the engine core. It also reduces the need for complex service.

It's a bit old fashioned, timing belts result in an engine that runs a little bit more quiet and they make for a lighter package. So it's easy to see why many manufacturers would choose that option. But MB got that bit right (they also got plenty wrong, their software for instance absolutely sucks).

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You are right that chains are superior to belts, but MB is hardly the only manufacturer using timing chains. Chains are actually becoming more popular, not less popular, especially as interference engines have also become more common.

My 2021 Mazda uses a timing chain. My 2004 BMW uses a timing chain. My old 1990 BMW had a chain. My folks' 2019 Lexus and 2016 Toyota both use chains.

Honda was a notorious holdout that still mostly used belts for a long time, but even they are coming around and some new models use chains now.

Interesting! So there is a kind of resurgence in this. Nice to see that other manufacturers take the longevity and service of their engines serious for personal transportation. There was a point in time where MB seemed to be the lone holdout and the only other manufacturers that used chains were mostly making trucks (and Porsche). To me it's a no brainer, especially with an engine where the pistons don't clear the valves when they are active. The kind of engine damage that a broken timing belt results in is usually enough to completely scrap the engine. I wonder if those other manufacturers chains are also rated for the life of the engine or rather not.

> I wonder if those other manufacturers chains are also rated for the life of the engine or rather not.

Mostly yes they are, which is wonderful compared to timing belts. It rubs my engineer brain intensely wrong to have such a critical engine component be designed as a wear item, especially when its failure can cause engine rebuild levels of damage.

However not all manufacturers' quality lives up to the intended design. VW/Audi have a spotty record with various well-known timing chain problems ranging from bad chain tensioners that fail and cause the chain to jump timing to plastic chain guides that break and wreak general havoc.

But for most cars a timing chain will last the life of the engine.

My '08 Civic Si had a timing chain, one of the few models that did at the time. Used to startle the service techs who weren't expecting it.

Yep, the N54 out of my 335i had timing chains. Replacing that during the engine build wasn't fun, but it was still solid at 130k.

  The main reason why MB lasts so long is due to a single component in the engine,
  they still use a chain rather than a timing belt. This one little change has so
  much impact on the rest of the engine design that they tend to last very long
  compared to cars that have timing belts.

No.

Timing chain vs gear vs belt has little-to-no bearing on the longevity of an engine. You can, for instance, build an engine with a timing chain that's prone prone to catastrophic failure of the timing components. Mercedes has done it twice so far with the M116 and the M272/M273.

  Suddenly a whole pile of stuff is happening inside the engine enclosure
  instead of outside of it reducing the number of seals and in general reducing
  complexity outside of the engine core. It also reduces the need for complex
  service.

Tell that to anyone who's had a Ford with the Duratec or EcoBoost and an internal water pump.

So 'yes' except for some exceptions that prove the rule.

So, no. GM's put out a fair number of stinkers including the Ecotec and the High Feature V6. Chrysler actually recalled their late 00s Hemi engines over timing chain problems. The previous owner of my E39 had to tear the whole engine apart because the timing chain guides failed (as they pretty much all do). BMW's later N20, N47, and N57(N) engines are also well known for timing chain problems. VW/Audi had plenty of timing chain issues with both the 1.8T and 2.0T. Let's not forget Audi's famous rear mounted V8 monstrosity. Jaguar's AJ8 was legendary for timing chain problems in its first few years. Nissan's had trouble over the years with the chains on both the V6 and 4 bangers…

Meanwhile people put hundreds of thousands of miles on Volvo's old four cylinder with a… timing belt which takes all of thirty minutes to replace.

Chains vs gears vs belts has no bearing on longevity. The big difference is that chains are smaller and when you need to work on a chain it's generally far, far more complex than a belt drive. Don't forget that engines like the Ecotec, EcoBoost, M272, N20, and 2.0T are basically the bread and butter of those companies. They are high volume mass market engines.

Mercedes tend to last a long time because they're expensive, people pay to repair and maintain them, and nearly any Mercedes part for any Mercedes car can still be purchased new.

You're welcome to your opinion, of course. Volvo has an excellent reputation. BMW not so much regardless of how they are constructed, Chrysler (at least the ones that I've had when I was in Canada) never impressed me from a technological point of view and it was in the shop quite frequently. And MB fields cars year-after-year that clock up 300K+ to the point that it isn't even something exceptional and as a rule with the original engine.

As for repair and maintenance: that's a nice bit of circular reasoning, the reason those parts can still be bought new is because there is still demand for them: the cars are still running.

When you start looking for cars that are 15 years and older (which is my bracket in NL) there really are only two brands that stand out: Volvo and MB. The rest are lucky accidents and this is reflected in the state of the rest of the cars as well. But as a rule car engines will fail well before the body does and with MB (and Volvo) it tends to be the other way around.

As an amusing aside, my 1995 Saturn station wagon had a timing chain. Thanks to a combination of design flaws, at around 70k miles, the chain skipped a tooth and the engine disintegrated.

But it wasn't just a matter of the chain. All Saturns burned oil from the git-go, and as a bonus, a low oil level would cause the timing chain to lose lubrication, thus causing it to wear out. People who religiously topped off their oil, every time they re-fueled, kept their Saturns for a long time. I was not one of those people.

My next car was a Toyota, which I still drive. The Toyota engine is designed to make it easy to service the timing belt at the prescribed interval, and the car consumes no oil.

Keeping the oil topped up isn't really a luxury! That must have been quite the thing when it happened. Were you in traffic?

I was at a stoplight. It just started making a grinding noise (probably the cylinders slapping the valves). I was not far from my regular repair shop, and drove it there. Later on, I returned to gather my belongings from the car, and the shop made it go away.

I'm definitely more careful with my newer cars.

My first car didn't burn oil, but dripped. I'd just top off the oil whenever I started hearing the tappets clicking. It was quite a forgiving engine, a 1975 Dodge.

The Mini I had was very much like your Dodge. There is a joke in Mini owner circles: "How do you know your Mini is out of oil?" -> "There is no puddle under it when you drive off".

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