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Naive question: aren't belts lower maintenance than chains, and don't let last longer? Why doesn't a engine with a chain drive require equal or more replacement

Naive question: aren't belts lower maintenance than chains, and don't let last longer? Why doesn't a engine with a chain drive require equal or more replacements?

jgilias 2y ago
Umm.. No and no. Belts need to be changed at some service interval, usually 100k SI units. If you don’t do it, a ripped belt wreaks havoc on the engine. Chains are typically installed for the life of the engine, and need to be changed only if it’s a problem. A caveat though. I used to have a Škoda Fabia with a chain drive, and I did end up changing it, as it started making the tell-tale sound when stop-go. In the context of hybrids though, I fully expect that chain to last the lifetime of the engine. The engine is under significantly less load than in a traditional ICE, so less stress on the chain. Also, for 100k mileage, the motor-hours that the engine has worked are less than in an ICE due to the engine regularly being off.
analog31 2y ago
Amusingly, my 1995 Saturn had a timing chain, and the chain skipped a tooth on its last day, at roughly 60k miles. Now, there wasn't necessarily anything wrong with the chain per se but it was the end of a sequence of failures involving the engine design. On all of our other cars (Toyota), the belts needed to be serviced at X miles, but it was actually a cheap and quick procedure.
frosted-flakes 2y ago
Unlike most bicycle chains, timung chains are permanently lubricated with filtered oil. Belts are not.
- bityard 2y ago
  Ford and a few other makers have been using oil-immersed timing belts lately. They quite reliably fail after the car's warranty is up but well before the rest of the car is junk.
  - datavirtue 2y ago
    I agree, they are a disaster. However, I have heard people argue that Honda and other manufacturers have been using oil emersed belts for decades. After 2017 Ford started using belts to drive the oil pump in F-150 engines (and possibly other Ecoboost engines). I have seen 100k teardowns of failed engines and the belt is not looking good at that point. If the belt breaks the engine is toast by the time the operator realizes what is going on.
hollywood_court 2y ago
No. Chains are better. My Land Cruiser has a timing belt. I replace it every 90k miles per Toyota's specifications. My Tundra has the same engine, except that it has a timing chain. I've never bothered to replace the timing chain. A timing chain is preferable as long as it isn't something like a Jaguar/Land Rover. The chain in those doesn't matter because they use plastic tensioners that eventually become brittle at crack/fail.
- datavirtue 2y ago
  Chains can stretch, weigh more and make noise. This is why belts are used, in addition to being a space saver. The ultimate in reliability are gear drives. Those truly never wear out or need replaced (found in nearly any diesel engine). Chains were very common in American cars and trucks for decades and they did need replaced after 150k-200k miles. I replaced the one in my 1993 Ford 5.0 at about 150k hard miles and it made a dramatic difference in performance (solved knocking/preignition on hills).
  - ek750 2y ago
    These days, there are some engines with (oil immersed) belts, but that's for fuel efficiency, not longevity. Chains last longer, typically, although I used to have a 97 Honda VFR that had neither. They started with chains in earlier models but had reliability issues so switched to straight cut gears. Man I miss the way those things sounded -- like a supercharger whine. Amazing

Naive question: aren't belts lower maintenance than chains, and don't let last longer? Why doesn't a engine with a chain drive require equal or more replacements?

jgilias 2y ago

Umm.. No and no. Belts need to be changed at some service interval, usually 100k SI units. If you don’t do it, a ripped belt wreaks havoc on the engine. Chains are typically installed for the life of the engine, and need to be changed only if it’s a problem. A caveat though. I used to have a Škoda Fabia with a chain drive, and I did end up changing it, as it started making the tell-tale sound when stop-go. In the context of hybrids though, I fully expect that chain to last the lifetime of the engine. The engine is under significantly less load than in a traditional ICE, so less stress on the chain. Also, for 100k mileage, the motor-hours that the engine has worked are less than in an ICE due to the engine regularly being off.

analog31 2y ago

Amusingly, my 1995 Saturn had a timing chain, and the chain skipped a tooth on its last day, at roughly 60k miles. Now, there wasn't necessarily anything wrong with the chain per se but it was the end of a sequence of failures involving the engine design. On all of our other cars (Toyota), the belts needed to be serviced at X miles, but it was actually a cheap and quick procedure.

frosted-flakes 2y ago

Unlike most bicycle chains, timung chains are permanently lubricated with filtered oil. Belts are not.

bityard 2y ago
Ford and a few other makers have been using oil-immersed timing belts lately. They quite reliably fail after the car's warranty is up but well before the rest of the car is junk.
- datavirtue 2y ago
  I agree, they are a disaster. However, I have heard people argue that Honda and other manufacturers have been using oil emersed belts for decades. After 2017 Ford started using belts to drive the oil pump in F-150 engines (and possibly other Ecoboost engines). I have seen 100k teardowns of failed engines and the belt is not looking good at that point. If the belt breaks the engine is toast by the time the operator realizes what is going on.

hollywood_court 2y ago

No. Chains are better. My Land Cruiser has a timing belt. I replace it every 90k miles per Toyota's specifications. My Tundra has the same engine, except that it has a timing chain. I've never bothered to replace the timing chain. A timing chain is preferable as long as it isn't something like a Jaguar/Land Rover. The chain in those doesn't matter because they use plastic tensioners that eventually become brittle at crack/fail.

datavirtue 2y ago
Chains can stretch, weigh more and make noise. This is why belts are used, in addition to being a space saver. The ultimate in reliability are gear drives. Those truly never wear out or need replaced (found in nearly any diesel engine). Chains were very common in American cars and trucks for decades and they did need replaced after 150k-200k miles. I replaced the one in my 1993 Ford 5.0 at about 150k hard miles and it made a dramatic difference in performance (solved knocking/preignition on hills).
- ek750 2y ago
  These days, there are some engines with (oil immersed) belts, but that's for fuel efficiency, not longevity. Chains last longer, typically, although I used to have a 97 Honda VFR that had neither. They started with chains in earlier models but had reliability issues so switched to straight cut gears. Man I miss the way those things sounded -- like a supercharger whine. Amazing