Engine timing chain vs timing belt: What's better? | Auto Expert John Cadogan

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[@AutoExpertJC]

Thanks to MANSCAPED for sponsoring today's video! Get 20% OFF + Free International Shipping + 2 Free Gifts with my promo code "AEJC" at manscaped.com/autoexpert

[@Ben-xy3jn]

I so hope ya shavin ya nuts..mrs cdog must be loving it..

[@markfletcher756]

Another reason to Boycott manscaped

[@julzb7165]

Just in time for valentines!

[@skataskatata9236]

what is really better? not chain. not belt. EV is better.

[@davidelliott5843]

Two stroke is better still. They are no longer dirty smokers. The Rotax ETEC 800 DI makes 160 bhp but is cleaner and more fuel efficient than competitors four strokes that are way heavier and double the cylinder capacity.

[@surferrosa1104]

I think chains and belts are both fine as long as its consentual and you use a safe word.

[@hdmccart6735]

nice...

[@bluddyrowdy8757]

Ohh so old fashioned...the newest version is to use wet-paper, and the game Stops if the paper gets broken !

[@jonwilliams4507]

Oh you bad person. I agree!

[@nickwheeler8231]

In these instances, the safe word is 'money'

[@brianwalker1933]

Good one. 😊👍👍

[@dperreno]

You. Nailed. It. Thank you for this video. As a (retired) automotive engineer, it is so refreshing to actually hear someone else say out loud all the things the voice in my head has been saying for the last 40 years! (and I haven't even got to the actual part of the video about belt vs chain) I was born in 1960 and I helped my dad with car maintenance starting when I was about 10 years old. Back then, we had to redo the drum brakes every 2 years (that included repacking the bearings on the front axle), we changed the oil every 3000 miles, we greased all of the zerk fittings on the suspension at the same time. We put on studded tires in the winter and swapped them back out in the summer, and replaced the tires after 20k miles. We even had to remove the head and get a valve job done on the Chrysler slant 6 at 40k miles. This was all considered routine back then. If a car made it to 50k miles, it was old. 100k miles and it was a story in the newspaper.

[@peterneumann1677]

John... I have to say. The audio from the paper toss at around 26 minutes sounds alot like a suspicious bounce along the ground. Indicating a miss. This can be compared to the audio from the paper toss right at the end, which sounds like nothing but bin. I think the only way to clarify this issue is the implementation of bincam. Thank you for the entertaining content mate. Great channel!

[@stephenwalters8061]

🤣🤣🤣🤣🤣🤣

[@godfreypoon5148]

Confirmed, 26:04 does indeed sound bogus.

[@atama01]

Wtf has this got to do with timing belts/chains……….but you may be right

[@murrieteacher]

I agree with Peter. And there are mitigating circumstances; you are a journalist and you yourself have questioned their integrity. Where is that bin cam you mentioned a number of episodes ago?

[@studley2436]

I'm wondering why such a really smart guy hasn't put the bin next to his workspace.

[@gregbuser4690]

The most reliable vehicle I ever owned was a Ford F-250 with a 300 cubic inch straight six. That engine had timing gears. Doesn't get anymore robust than that.

[@Paul-45-70]

@@theaustralianconundrum that was a pretty common problem in the Holden 6 cylinder.

[@Low760]

They do fail if they use a fibre gear like on 202s or Volvo ohv redblocks

[@DTGTDetectingTheGoldenTriangle]

I'm still driving my f250 😂👍

[@2148aa]

Don't forget the 3 speed on the tree.

[@grahampearce6462]

@@holleyman1970 what mainstream car uses gear driven cam, even in the last 20 years?

[@trevordehaan4069]

The best way to preserve a car's life is to change all fluids regularly, had a 1994 Subaru that was still running well after 410,000ks and my dad had a Toyota that went more than 500,00k all by changing the fluids regularly.

[@ToyotatechDK]

Very good video with a very well explained topic John. Been a Toyota mechanic since 1996 and I’d say that all the bigger problems with engines started with timing chains combined with the prolonged service intervals as you also mentioned. Belts give you the normal change interval where chains only have recommended change intervals and audible warnings. Newer engines are notorious for chain rattle at relative low mileage and that is by far because of cheap parts or poor design from factory.

[@fanman4230]

@ToyotatechDK I too was a Toyota Tech, from 1979 to 1988 so a bit before you. It's all down to design and usage. Toyota had an engine called the 18R, this should have been a bullet proof timing chain assembly as it had two short duplex chains, slippers and hydraulic tensioners, but no, we'd have two or three of these a month in the shop for knackered timing assemblies. Then the 21R engine appeared, this had a long single row chain which, you would think was a step back, but no, I never had to replace one. It just goes to show the variables that exist even within the same type of drive and same manufacturer.

[@josephstratti52]

Really what audible report do you get before a timing belt breaks and belts have a recommended changing life much shorter than most timing chains.Prefer the chain over most timing belts thanks ,just my humble opinion.

[@kevinschilling1150]

Yes indeed,but timing belts are simple and less complicated to change. Had two diesel vehicles with belt driven ohc ohc and they were simple and quick to change every 100,000 km.@josephstratti52

[@matsim0]

Regarding chain stretch: ECUs that control camshaft phasing detect chain stretch and adapt the phasing to account for the stretch.

[@jessebrown1400]

Glad someone mentioned this.

[@chrisblockley5783]

I admire you for plugging Manscaped without bursting into laughter.

[@lancelot1953]

HI John, I love to hear your reviews -- it is both enlightening and entertaining! Your mastery of the intricacies of the English language even from Down Under is legendary (or the medication(s) you are on are no less than miraculous). Listening to your car/truck lectures is like having an automotive engineering lesson presented by no less than William Shakespeare or Victor Hugo (for French continental engineers). Peace be with you, Ciao L (Ford engineering, from Up Above, 1972)

[@andysaunders3708]

Treatise.

[@hackney7106]

Fascinating John! My vehicle has a wet belt.The service interval is 10years OR 240,000kms. Oil changes & on time is critical with this engine.

[@craigquann]

Oil changes are critical for chains too. That the #1 reason chains fail so commonly now. The extended oil change intervals leave too much crap in the oil that chew up the links.

[@hackney7106]

@@craigquann entirely agree.I try to change mine about twice a year.

[@craigquann]

@@hackney7106 likewise. I have a truck/ute as a daily driver that sees about 15000km a year. And my wife's SUV that sees about 5000km a year. Both get changed twice a year. Once in April and once in October. Best part is 10L (2 jugs) does both as it's the same grade required for both. 5.7L for the truck and 4.4l for the car. I wait for my brand of oil to go on sale, with manufacturers mail in rebate, the sale and the cost of the filters. I can service both vehicles with premium synthetic for $100.

[@jimamizzi1]

@@craigquann absolutely correct, but some people still don’t get it, with belts when your book says change belt at …klm change it

[@hackney7106]

@@craigquann Mine is a Fiesta ‘S’ with the Ecoboost 1.0 3 pot turbo engine.Cracker of a car.But they are known to snap their wet belts, especially with a poor service history.The belt degrades over time & blocks the oil pump up,causing the engine to think it is low on oil.Once that belt does go it’s all over red rover.I am very particular when it comes to services on it.Imperative that the correct oil is used on them.Mine is fine @ the moment,94,000kms on it.Puma has now gone to a chain setup(same engine).Still would not get rid of it though.Not many mechanics will touch them, as they need specific tools to get the belt off,quite a major job, roughly a 6 hour odd job.

[@DTGTDetectingTheGoldenTriangle]

Gear driven all the way 👌

[@nickbouvy6524]

Unless it’s a Mercedes

[@margarita8442]

bevel gears

[@dougstubbs9637]

Never had to change the fibre bakerlite cam drive gear on a Holden Starfire (moon glow) four, or later black six ? The change was made for quietness reasons, and durability be dammed.

[@dougstubbs9637]

@@margarita8442 my last Kawasaki, a W800 had a bevel driven shaft for the SOHC. Dukes had the same. Noisy.

[@DTGTDetectingTheGoldenTriangle]

@@dougstubbs9637 nar mate I'm a heavy diesel mechanic they are all gear driven some timing gear sets with over 4 million kilometers and still in good working order 👌

[@johndaly8060]

Great report John. I agree with every word but I still prefer gears over both chains and belts!

[@chrisjohns9631]

How many cars on the market with gear driven cams?

[@tomr6955]

​@@chrisjohns9631 just 1, John's!

[@chrisjohns9631]

@Tom R which is? My name is Chris btw...

[@johnm948]

@@chrisjohns9631 the only one I ever had was a 1986 Saab 900 with dual OH cams. great engine and other mechanicals but an electrical disaster. By the time I got rid of it in 2002 I had replaced about half the wiring harnesses with #14 cu control cables.

[@godisgr8466]

​@@chrisjohns9631good question.

[@marklittle3551]

Another excellent report John! If I intend to keep a vehicle more than five years I err on the side of 10k oil changes. Got 530k out of an AU ute I used for work before I traded it. If people are going to go the 15k interval at least check the oil level at least every 5k so it doesn't run low on oil which can happen with modern petrol engines and extended service intervals.

[@billwienands7298]

I like your idea of checking the oil every 5k but how meney will know how to

[@marklittle3551]

Yeah I know what you mean Bill. My kids gave me a hard time over insisting on servicing checks etc. I look upon knowing how to check the oil as rudimentary as changing a flat tyre. Sometimes hardest lessons are the best. Low coolent blow a head gasket or low oil damage engine internals etc.

[@BryanTorok]

Two stories of timing chain vs. belt. Back around 1981 my brother gave me his 1969 Olds Cutlass (same body as the 442) with the rocket 350 V8 (350 cubic inches, 5.7 liter) because it had stopped running. The timing chain had not broken, but had skipped a tooth or two. I replaced the timing chain and sprockets and car ran poorly, back firing through the carburetor. It turns out that engine is an interference engine. Because it was a high compression (10.25 : 1) the clearance between the valves and pistons was very tight. If the engine went out of time the pistons would strike the valves while they were open and bend the valve stems and possibly damage the pistons. I eventually got all that repaired and it was a great engine. About 2017, I bought a 2005 Toyota Sienna minivan (you call them something else in Australia) with 205,000 MILES on it from my brother-in-law. As Toyota recommends changing the belt at 100,000 miles and it was twice that, I had it changed at the local Toyota dealer. It was $550 labor to change a $25 belt. As the labor to change the water pump is almost identical, the mechanic recommended changing the pump for an additional $50. Still starts on the first try.

[@jakelowang4132]

I did change my timing belt on my civic 1996, i just replace the belt and tensioner, 2 days later the water pump started to leak so i bought a new water pump and replace it. Now a days the timing chains his way more expensive.

[@z06doc86]

Virtually every engineering choice is a compromise, and so are most choices in nearly all aspects of life. Nice video John.

[@Verschlimmbesserung]

Words of wisdom imparted.

[@1969cmp]

The Barra. Fantastic engine.

[@aslkdfjhg]

Even on motorbikes I've found that timing chains are regularly lasting a lot longer than before, probably due to superior oils, oiling system and cooling.

[@russcattell955i]

For sure, just about all bike engines (Ducati a belt exception & short service life) have cam chain but are shorter, cam to crank. So shorter chain, less stretch. 12,14,16k rpm is common on 4 cyl sports bikes. The engineering is outstanding.

[@paulg3336]

@@russcattell955i A single (an OHC V-twin cam drive can be considered to be two singles) is particularly harsh on belts and chains due to a highly fluctuating torque requirement. The more cylinders controlled by the camshaft the more even the torque requirement is.

[@partymanau]

@@paulg3336 But more constant load, less snatch. ( tho sometimes less snatch is bad.)

[@MotoBreno]

@@russcattell955i Two cases in point from my bikes: Both with the same shortened period service intervals, notably: Fresh oil & new filter at: 800Km, 2000Km & every 3000Km thereafter. Both ridden almost to their engineering potential (Daily-ish, Summer, Winter, Sun, Rain, Hail, Snow, Interstate Touring & occasional Track Days) The '91 ZXR-750-J1: Timing chain within stretch spec and on OEM tensioner and guides all the way up to when it moved on at over 120,000km (in that period, it only ever needed 8 (of the 16) valve shims swapped out ('finger-follower' between the lobe and shim) for 1 increment difference and cam lobe hard facings were barely scuffed) - '01 ZX6R-J2: Identical results and lack of wear to the ZXR except for, it now has 95,000Km on it and has never in its life reqired a valve adjustment (these are 'under-bucket' valve shims) - Look after it, and it'll look after you.

[@paulg3336]

@Retired Bore Sprocket diameter matters too. A small diameter sprocket requires more rotation around each link pin causing more wear

[@andrewb8548]

A stretched chain should throw a code way before it starts running rough. There gets to be a disagreement between the camshaft/crankshaft position sensors. The biggest issue with modern chains isn't the chain, it's the plastic tensioner guide. They get brittle from heat cycles.

[@ThisFinalHandle]

I've changed a belt on 5VZFE (Toyota V6) 100,000km+ over its replacement interval. And changed stretched LY7 chains (GM V6) before their first replacement interval.

[@Eagleburger90]

Mine is at +120k. 5vzfe

[@theairstig9164]

The 5VZFE is a non interference design. Nothing to see there. Move on

[@chevalsauer]

Top video and explanation, totally explaining da pros and cons of both. I own an old(ish) 2001 camry wagon 4 banger, currently clocking in at 433k ks. Simple, reliable non interference engine as you know. Did the entire belt job myself about a month ago, good for another hundy... I just want to say, simplicity is King! And it also explains why Honda still use belts in a lot of their engines. Gone are the days of the ole 186 shredding the gears leaving me stranded, and the occasional gear linkages getting jammed up in the middle of an intersection, will never forget the ole hip bump maneuver lol. Non petrol heads will never understand, the only sad part about that is the many dishonest bar stards taking advantage of that! I didn't know about the inertia thing of the chain, but makes perfect cents!!! Adding more developments and costs. Cheers from across da ditch cobba!

[@kerrynball2734]

I had the belt go on my 1991 camry that we just purchased with 200k on the clock. One of the pulleys had a bearing failure and it rubbed the belt on a waterpump bolt Had it towed home, and changed it where the towie managed to put it in the middle of the front lawn for about $150 and that was it, no problem.

[@stevezodiac575]

Loved reading that!👍

[@MattExzy]

My '05 Camry has the chain. But I've owned cars with belts. I can go either way, really. But I do prefer the idea of being able to routinely replace a belt vs. the unknown state of a chain that has no given service interval.

[@MrAndrew1953]

Just had timing belt replaced in Peugeot 307 wagon. It’s supposed to be replaced every 7 years or 150K before it perishes and causes engine problems. The car has done 102Ks,13 years old, diesel. Cost was $1,100.

[@andrewinaustintx]

Good presentation on the topic - especially with regards to increase oil contaminants as a result of short commutes. My personal truck with a Toyota naturally aspirated, (2UZ-FE), 4.7 liter DOHC has a timing belt. It is definitely a solid small block V8 engine - but dated in 2023.

[@Beer_Dad1975]

I've replaced a few Toyota/Lexus 1UZ-FE timing belts over the years - really not a difficult job at all - in my experience the OEM belts are good for at least 150,000km.

[@TheObersalzburg]

As someone who does as much of my own maintenance as possible, I'll go with the belt. Why? No concern with oil leaks when replacing the cover (which can get tricky), no gasket surfaces to immaculately clean, no chance of oil contamination when cover is off, and a little less mess. However, I don't see either choice as a deal breaker when buying a vehicle in the bigger picture.

[@jessebrown1400]

I've heard several instances of timing belts snapping on ppl and destroying engines and I'm not that well versed. In comparison I've never met someone who told me their timing chain snapped. When the belt goes you can be sure it will be far from a garage. Pack the necessary wrenches and an extra belt somewhere in the vehicle for this occasion and you should be fine.

[@TheEulerID]

@@jessebrown1400 It happens, especially on some BMWs (and others which used those BMW engines), usually because something breaks in the chain tensioner/guide area. There are also certain VW/Audi models which have troubles in that area.

[@jessebrown1400]

@@TheEulerID good point, that would definitely take out the chain. BMW's are really bad for stuff like this, VANOS cams come to mind particularly, and Cummins with the defective hardware falling into cylinder #4 Bye Bye Cylinder Head.

[@TheEulerID]

@@jessebrown1400 On one BMW engine design (and I think an Audi one as well), they even put the timing chain on the back of the engine, so at the very least the gearbox had to be removed to change the chain, tensioner and guides, and in some cases it was an engine out job.

[@jessebrown1400]

@@TheEulerID this is why I will always drive the M and G series Suzuki's in longitudinal setup, sooo much room to work on everything, chain on the front, bell housing bolts easy to access, starter easy to access (relatively), transmission comes out easy, only thing that's a bitch is the block heater hoses smashed up against the firewall. In the future I am going to Tig weld 90° elbow bungs into the firewall to route the block heater hoses better and possibly threaded liquid tight connectors instead of hose clamps.

[@TonyRule]

Yes, there have been some dud chain driven OHC engines, but the vast majority do not ever require a timing chain replacement, while belts are always a service item with age or mileage - whichever comes first. My 370,000km chariot is on its original timing chain and it's not going to need to be changed any time soon because it's still quiet and the tensioner still has plenty of range remaining. Timing belts are fine, so long as you can get to them for easily replacement, and they do have some benefits, but none that I consider are of any value to me.

[@911engineguy]

I fell for it. I tried to swat the fly on my screen...

[@Justadudeman22]

​@@911engineguy haha

[@ashleypayne4671]

You were on the money John. The BMW N47D20 engine were well known for timing chain failure due in part to chain guide wear. Interestingly the research I did on the matter, seemed to only really occur in vehicles that were serviced when the onboard system called for it and usually well before the 200k mark. I was fortunate to achieve almost 300k with no failure. I can only assume that it was due to the 10k max oil change intervals.

[@swamp_dog]

Thank You for the info

[@spacey22]

Most BMWs with chains are problematic

[@janstafford1490]

Well cheers for that John ,I was always a chain guy, remembering seeing a chain on me pops merc W114 we clocked 750k replaced one gearbox and 3 intervals of 4 injectors ( nozzles only ) at around 7 quid each and still got 42mpg about 6.7 / 100km but as natural asp. 0 to 60 in an hour or so I guess it wouldn’t entertain the stresses of a modern car but it was a momentum motah. My feelings have chain-ged 👍🏽

[@lesmond7301]

Love your video and can not wait for the next one. Any chance of setting up a camera for your rubbish bin, for those live action paper ball shots? Regards,Lesmond of Nu Zeelandstan :)

[@MrCountrycuz]

I have a 2014 Acura TSX with a 2.4 ltr 4 cylinder engine that has a chain. I bought this car in 2017 with 18000 miles on it and now it has 128000 miles and the only thing I have done to this car is change the oil and the spark plugs. It gets around 30 mpg at 80 mph. I should probably get my chain inspected to see if the chain tensioner needs replacing as I have read that this chain will outlast the engine but the tensioner has to be replaced around 130000 miles. It’s a great car.

[@FastFless]

Great video - specially about chain stretch. Just one small point about 'total' chain stretch. I think it's the measurement of stretch on the drive side between the crank and the cam sprocket/s that is most critical. The chain stretch on the return path from the sprockets back to the crank is of less relevance, as slack is taken up by the tensioner.

[@stevezodiac575]

Astute observation!! I think you might be right! Although, I'd be surprised for John to overlook that detail. Hope he clarifies..

[@TheEulerID]

Very true, and the side under tension will also be the shorter path as it's the direct route. Perhaps only 1/3 of the length of the chain is under tension, so John's 1mm will be about 1/3 mm.

[@anthonyjackson280]

Unless it is a dual OHC, driven by a common chain, then the stretch will effect the timing between the cam shafts to some extent. I still prefer chain to belt though as I routinely drive 60,000 Km/yr.

[@jonwilliams4507]

I seem to remember in the60s, 160 k on a Holden motor was time for a rebuilt repco short motor. I’ve had bf gas falcons do 1 millions k’s and still going well. Reliability of engines is these days is incredible. Love the Barra’s.

[@wobblysauce]

Yep, oil change every 10k, cheapest oil don’t look at the viscosity change filter every 2nd time maybe, only look at it if it makes a new noise

[@georgecurtis6463]

As a retired long time mercedes mechanic, yes we dealt with timing chains. Can you believe mercedes had no recommendation for timing chain replacement. We just went by start up chain noise. But later on we found that synthetic oil basically stopped chain wear. There is much more to the whole thing but that's the short version. I have a subaru and as it's not driven much, I replace the timing belt and assorted things every 6 years.

[@Leonardo555ZZZZ]

Some MB engines had problematic timing chains ,,eg M271 ,,whereas others were bulletproof ,eg ,M112 double row.

[@indrjithbdeva817]

Yes John, I do understand that the goal post has moved on and reliability has improved, but on the contrary parts are being produced to last only a certain life time (Warranty period & not much more) and are not over engineered like before, just to save some money ( Nice use of tech like CAD & simulation) case in point, the plastic thermostat valve housing on a certain brand. I bet you know this too, You should have brought it to light, just for comic relief.

[@bobdadruma]

The belt has less resistance and it is easier to replace than a chain. Belts were once not very reliable but they became very reliable as time went on. As an auto tech with 45 years experience I side with the belt.

[@petesmitt]

A mate of mine with a Jap car went 280,000 km's and 12 years before the belt went bye bye..

[@AutoExpertJC]

The belt also has less inertia.

[@alouisschafer7212]

yeah these days they last forever and even when the rubber starts to perish and crack they will just soldier on for longer than you may think

[@TonyRule]

*_"As an auto tech with 45 years experience I side with the belt."_* Of course you do. You have a boat to run . ;-)

[@prizecowproductions]

With all that you said do turbo diesels with higher compression run to a different rule. I ask as a truck driver and hopefully soon to be a 4wd diesel owner. Thank you always appreciate your dry sense of humour as well as your engineering aspect. Be well be safe. Jeff Moore

[@carlmoll3345]

Brilliant John. A clear explanation. Cheers, Carl

[@AutoExpertJC]

No wukkas Karl.

[@1Longranger]

Agreed. Great explanation, John. We own vehicles with either chain and belt camshaft drives. Maintenance as always is the key to hassle free motoring. Just as an aside, not all belt drives have self-adjusting tensioning mechanisms. For example, the balance shaft drive belt tension on MN Tritons require periodic adjustment that skimping on can result in that belt failing. Fortunately it is a piece of piss to adjust and can be done in a few minutes.

[@djmjd]

This is the best discussion of this topic I have ever heard.

[@DabDabGoose]

The best is the one that has it easily replaceable, for example while a chain will last longer in most cases some brands like Audi have it on the back of the engine for their 6 cylinders and above, so it's an engine out job that can cost 10k, it's also an interference engine so you must replace it before it breaks of the engine is toast. A non interference engine with a belt that doesn't require and engine out job is as good as any chain on a regular car.

[@timlarcombe6831]

John, I was of the vintage when holden red motors had fibre cam shaft gears, which used to fail with alarming regularity, my first job when I started my apprenticeship way back in 1979, fuel was 20 cents a litre, loaded with lead and a schooner of beer was 45 cents, lovely times

[@michaelbradley3393]

Yep I’m familiar with that … solved by cleaning the oil supply to the gear and fitting an aluminium gear.

[@michaelbradley3393]

I was also a mechanic then and I was gobsmacked when I had to rebuild a black 6 cylinder in a VK commodore and found it had a fibre cam gear! Talk about straight outa 1963!!! It was so good when they replaced that venerable but past it boat anchor with the Nissan 3 litre.

[@adventuretimephotos2423]

I always hear people (particularly in the 4wd world) make statements like “chains are much stronger and last forever, belts are just ticking time bombs”. All my cars have had belts and I’ve never had an issue with one, and always replaced on time. I know two people who have had chains fail, and the engine shit itself. I don’t believe chains are any more reliable than belts 😊

[@aussiebloke609]

As a rule, I've found that a chain used to always give some warning as it became increasingly noisy, whereas a belt will work perfectly until it goes snap. That's only really a factor if you're not doing your belt replacements on time, but a lot of people are in the camp of "She'll be right for another month...or three..." until they forget about it and the inevitable happens.

[@partymanau]

Yeah, pull half the car apart every 80k miles. No thanx, chains are for life.

[@MattExzy]

My current car uses a chain, but I agree, I'd prefer a belt to a chain, since they have set intervals to be serviced. With a chain, I don't know what's going on and what state it's in. Never had a belt fail on other vehicles I've owned that used them. And we're talking about something that pretty much outlasts virtually every other serviceable component.

[@alanjm1234]

@@partymanau on most cars a timing belt change is a 2-4 hour job. On my car it's interval is 200,000 km. Gives that the Hyundai in the video needs a new chain at 140,000, and it's going to be a much bigger job, I'd say belts aren't so bad.

[@TheEulerID]

@@partymanau have you ever changed a timing belt? If you are pulling the car half apart, then you are doing something very wrong. On my Ford Focus a decent mechanic can do the job in two hours. I think I could do it in less than four.

[@Shenkosky]

My 1998 Yamaha 50hp outboard has a direct worm gear and still runs great along with my 70 year old tractor. All original never changed any worm gears yet! No chains or belts at all! They definitely don't build them this way anymore because they want high RPM and gas mileage over tank-like durability. They both have carburetors I've never cleaned! Because the needle holes are gigantic before emissions started making them so small they clog up all the time. Sure they are better in those aspects but you would say I want efficient motors well these are not that they are simply simple and will run forever as long as you make sure you have oil and gas in them. Funny thing is unlike modern cars the oil never looks or gets dirty at all because there are no EVAP systems pumping exhaust gas into the intake system making your oil dirty in the first place.

[@dogstar234]

Would love a video on "wet belts" as a follow up to this one :)

[@johnwade1095]

They terrify me. Don't expect me to buy one.

[@nickwheeler8231]

Wet belts combine the disadvantages of both chains and belts with none of the advantages of either. Then they add their own flaws, like the horrendous amount of time it takes to change one - 10hours for the ghastly 1.0l Ford Ecotec, which instantly sucks up all the 'low running costs' of the previous ten years. I'd put money(although not the £1500 a belt replacement costs) of the designers speaking German as their first language.

[@johnwade1095]

@Nick Wheeler an affordable engine doesn't have serviceable components wet side. Cracking the engine open is an admission of failure.

[@jeffk464]

@@johnwade1095 kind of agree with this, with the chain the hope is you never have to have it worked on. We had a guy at the Nissan dealership that spent a lot of his time replacing the chain tensioners on the 4L, hope doesn't always work out. Nissans other engines didn't have this issue

[@johnwade1095]

@@jeffk464 I had an S14A many years ago. The engine was great, the rest of the car, not so much. The biggest problem was probably Nissan.

[@csjrogerson2377]

More words of wisdom from JC which I wholeheartedly endorse. My little Mazda 2 turbo diesel here in Thailand has a 6 month/10k Km service interval. Only do 10-12K Km/yr, but the services are done every 6 months on the dot. It has a timing chain which is "maintenance free (BS)" and I tried to get Mazda to be more helpful. They wouldnt. Just decided to wait and listen for the timing chain rattle. PS. The servicing here is dirt cheap about A$100 and most of that is the synthetic oil.

[@stevezodiac575]

Appreciate the updated and detailed information! Awesome job!

[@mcmoose64]

All of my cars have been purchased 2nd hand , usually with around 120000 ks on the clock . Because of this I prefer timing chains , that way I don't have to budget for a new timing belt at around the same time rego and insurance is due . My favourite form of cam drive was the gear driven system on the v4 Honda motorcycle I once owned.

[@Ernst12]

Even timing chains can stretch if the oil changes are not made correctly and in time or if the incorrect oil not specified by the manufacturer is used. Especially with expensive cars, one of the main premature timing failures anywhere between 90-140 km is due to neglect in servicing the car as specified by the manufacturer.

[@robertpross7515]

@@theaustralianconundrum Because they were noisy ?, not a problem on a motorcycle (car would be different), I recall them lasting forever, so reliability can't be the issue ?

[@davidbrayshaw3529]

@@theaustralianconundrum They were a heck of a lot better than the system they replaced (timing chain). The problem was that you couldn't machine the head or block deck, in the unlikely event that it was required. And take yourself back a few years, they were incredibly good engines, for the time. 100bhp out of a very civilised 750 cc was nothing to be laughed at, back then.

[@kerrynball2734]

That's an excellent explanation. The belt on my 2L Toyota Engine standard interval is 100k. And you really need to not mix them up when your changing it because they look as good as new after 100k. I heard that they upped the interval to 150k. On my VW, Golf the water pump seal went before the service interval for the belt...... and I suspect it's going to do it again.

[@krissteel4074]

I've never really had a problem with belts or chains, people also have to factor in their big service will usually include a water pump, 2-4 tensioner or pulleys, a gasket and O-ring or two. Most of the time they'll also like you to throw on some new accessory belts and stuff + 5-6hr labour. So its not a minor bit of work and can take a bit of time depending on the engine, so it comes in around the 1200-2000 bucks.with a decent mechanic (including the parts)

[@davidnorton5887]

Plus there is also the risk that the work isn't carried out so well - right procedures, torque setting etc, that only come to light a bit later on, but hard to attribute to sloppy work. Hence I do mine myself.

[@andysaunders3708]

Belt replacement in my shitheap is an engine-out job, according to the "agent". Funny how the entire belt-replacement kit comes to less than a fifth of the $3500 cost. Do it at service intervals of 10,000km. Been done once. Engine runs fine, but has to be done again, according to the official numbers. Very annoying that all engine mounts, officially, have to be replaced at the same time. Also funny how others can do it, engine-in, for $1200 up. If my back wasn't munted, I'd do it myself, at home. Chain vs. belt. Chain ok if oil changed regularly. Belt a bit of a ticking time bomb - lucky for me, mine is a non-interference engine. Always been a big fan of pushrods...

[@andysaunders3708]

Edit: Service interval - belt replacement is 100,000km.

[@Beer_Dad1975]

So this fella has had his vehicle since 2015 - 8 years, 150,000km - break it down based on his quoted $1,800 job to do the timing chain - $225 per year, or 1.2 cents per kilometer. Peanuts compared to the rest of the costs of owning a vehicle.

[@geoffbell166]

I do my Lexus V8 belt myself,Toyota genuine only takes me 8hrs because i take my time...old belt still looked like new .

[@darrenwidas2473]

Always agree with your commentary. 😁 Have owned/own examples of all types with good and bad examples of all. From 300K without a thing needing to be done to a 2010 Genesis Coupe 2.0T GT R-Spec with a chain that stretched out (jumping a tooth) in 80K; it got replaced with an Evo X chain and it was like comparing a bicycle chain to a motorcycle chain. BTW dad taught me oil is cheap insurance so I take service intervals and divide by 2. If you want long(er) life you hav3 to service often. 🤷🏼‍♂️

[@JohnSmith-yv6eq]

For diesels... why not a steel timing gear train? (you aren't worried about noise..it's a diesel)

[@AutoExpertJC]

$$$$$$$$$$$$$$$$$$

[@NSW2040]

Like a Cummins

[@petesmitt]

Timing belt for mine; quiet, no stretch; where timing belt engines have the belt spinning the water pump; change the belt and pump at the same time; thereby the water pump gets replaced before it fails, which is a good thing..

[@lethalz9]

Straight cut gears on a 186 high compression block 😍

[@JohnSmith-yv6eq]

Better than the OEM fibre timing gears on other Holden engines?

[@lethalz9]

@user-bo7zv4dl4t I forget what brand I got, but I had a Crow mid torque cam with Yella Terra roller rockers. Sounded sweet and went quite well, for those days.

[@partymanau]

Is that u Plankman?

[@lethalz9]

@@partymanau Plankman? 95% certain it's not, but there are definitely parties I don't remember...

[@theairstig9164]

If it’s too loud yer too old. Got it. It’s people with gilmer style drive belts on their alternators and straight cut gears that make me so glad that BEVs are taking over

[@ΓΡΗΓΟΡΙΟΣΚΩΣΤΑΚΗΣ]

ONE OF YOUR BEST EDUCATIONAL VIDEOS! congratulations!

[@kyle782]

There seems to be an issue that causes most of the issues when it comes to maintenance of anything these days, especially with cars and homes. People have forgotten how to effectively budget. People also waste money on non-essential things. My family has a budget of 4k a year for maintenance of vehicles alone. This allows for proper servicing etc. It really comes down to people's priorities, and how many people have them wrong.

[@postersm7141]

By the way, this new 10,000 mile oil change interval is crazy. I still go no more than 5000 even with full synthetic. For whatever reason I change my oil even more frequently on my motorcycle.

[@johnfranklin5277]

My new car is GDI, and TURBO. I love it! Hence its prone to fuel oil dilution. I normally change my oil every 4000 miles. But on this car I'm doing it every 3000. While I don't notice an increase in level on the dipstick at 3000 miles, I can smell gas in the oil. Hopefully this will prevent engine and Turbo failure. I'm sure manufacturers are well aware of this problem, but still states 9000 mile oil change intervals !

[@dougstubbs9637]

Once apon a time, I was shaving down, there, unfortunately not using Manscape Product, and slipped in the shower. Long story short, the wound required adult circumcision. On the upside, I ended up with a spare Serpentine Belt for the V6 Commadore.

[@TonyRule]

I didn't know they were a stretch fit belt. Even then, that's a hell of a lot of stretch! ;-)

[@RedDog265]

Thanks John, I appreciate the clear explanation.

[@Khakhees]

Ooh, what about timing Gears? I've wanted a vfr750 for a while, partly due to that unique v4 gear whine.

[@pjmack75]

Had one for years. Awesome sound.

[@johncrowley1203]

Those bikes had a magic speed where, if you got your head down below the windscreen, the exhaust sound largely disappeared and the whine from those cassette gears sounded like Satan himself was whistling between your legs. Great stuff. Wasn't that a 12,500 rpm redline on that motor?

[@SoulTouchMusic93]

I have a mate with a 1200. Maybe get that? They seem nice sports touring bikes but they're tall and heavy BTW.

[@TonyRule]

@@SoulTouchMusic93 The VFR1200 has to be one of the ugliest of the VF series. I've had a VF1000R and just loved the sound.

[@btnetro]

I was having endless debates with people and then this video... spot on. Now I can forward it and have a point. My motto used to be yeah chains last long but tensioners... not so much. Improper oil is also a major factor like in UK for example people don't maintain their cars (at all) and when they do they pinch pennies and say yeah mate put 10w40 half the price of 5w30 :)

[@Acceleronics]

Every design engineer immediately asks "Better for what?" because they know every design is a compromise.

[@AutoExpertJC]

Yeah - quite. Then the beancounters pounce...

[@johnfranklin5277]

Hello from Southern California. In 1977 I bought a 1968 Mustang from the original owner in excellent condition, except for one thing, the owner immediately disclosed to me that the timing chain had jumped a tooth and needled replacement. The engine ran well in park, but when i drove it, there wasnt much get up and go. I was 17 and really liked the car, 289 v8, automatic, factory AC, power steering light blue 2 tone blue interior, white vynil top...yup. Perfect. I bought it for 500 dollars. Of course that was alot more money then than today. So.....I was driving along about 3 days latet took a dip in the road the car suddenly just died. Thaks to Grandpa, a nrw chain was installed and wow!! It had plenty of get up and go! I still have it, its in beautiful condition, and still running great. Also i have 338.000 miles on my 94 Trans Am I bought new, original timing chain, engine never been touched. Still runs like new and i dont hear any strange sounds from the engine at all. Ive put well over 200.000 miles on several other cars and never had any chain issues. Just my experience with them. Enjoy your channel !

[@buncha5651]

I am an Automotive Engineer and i have seen cars with fibre timing gears that loose teeth, chains that stretched and broke tensioners, timing belts that snap, all with catastrophic outcomes. The timing belt faze has moved on and now most manufacturers use chains. My view is that modern engines with chains which are now in the majority are the best choice today.

[@theairstig9164]

No mention of the move to dual VVT being ubiquitous?

[@tjroelsma]

VW/Audi owners of cars with the FSI or TFSI engines would disagree with you. VW re-introduced the old problem of timing chain stretch ruining engines on those engines by using cheap chains. As to belts: under normal circumstances (no oil leaking on the belt, no overrevving the engine etc), a belt is free of problems up to the belt change interval. Most of the belts that do break, having either been mistreated/have oil leaked upon them, or haven't been changed according to the maintenance schedule. This is the old "the engine/gearbox/whatever is shit because it broke down. What? Did I have it serviced as per the maintenance schedule? Of course not, don't be stupid! That's way too expensive" idiot car owners reasoning that never made any sense.

[@hughcoleman3866]

After the hydraulic tensioner failed 8k after a full timing belt replacement on my 2013 2x4 Triton, resulting in a cactus head and a 4 month wait for a rebuild (mid Covid lockdown) under warranty, I took it straight out after I got it back and traded it on a vehicle with a chain and a non interference engine.

[@tba3900]

Who could forget holdens fibre camshaft gear.

[@robincurwood]

Hi John, have you heard of the Deltic locomotive/engine. They typically did a million miles before needing to change the engine. They are driven by gears . The Deltic engine is a 6 piston 3 cylinders to one row.( Two pistons in one cylinder.

[@MattBlack6]

My 1HDFT, belt. Needs to be changed every 100000km or 10 years. But the job is a piece of piss. Our former Honda Odyssey with the 2.4 K series engine is a chain. Was a bastard to get to anything on that motor, pretty glad that at 400,000km it was still running fine

[@dougstubbs9637]

Years ago, when on the spanners, I had a failed chain on a V6 Odyssey, came in on a tilt tray. Vehicle had not been serviced in 140,000kms. Had to drop the entire transaxle unit to even get to the donk, the internals of which were mashed. We couldn’t locate a reasonably priced replacement engine, and the owner abandoned the vehicle to us. A ratshit condition honda, which never seen a workshop hoist in yonks is worth 5/8 of fuck all, and the disposal didn’t cover workshop hours. The owner, who purchased the thing second hand, went off for donkeys age’s about how crap new cars are. Suck me off with a bilge pump, mate. Oil is heaps cheaper than machined metal.

[@gregspencer7111]

BinCam would be an interesting addition Mate. I appreciate your commentary John. Cheers

[@petercameron8832]

Well put. I found out to my chagrin all about this 20 years ago, bought an old 735i and enjoyed it for 18 months despite regularly changing the oil etc. it shit itself spectacularly when the timing chain let go. The plastic sliders the chain was tensioned by( for the backlash) wore out. Probably because the tensioner was controlled by oil pressure. The mechanic who gave me the verdict said “ its a throwaway “ ! Devastated I was.

[@p38arover22]

I have similar concerns about the quad cam BMW M62TUB V8 in my Range Rover L322 at 260,000km. I replaced the tensioner last year (easy to do) and that quietened the chain but the concern are the plastic chain guides. I will have to tackle this job myself as BMW mechanics aren't that interested. Our Turbo Forester (quad cam) is coming up to 100,000km so the belt is probably due for a change. Interference engines are worrisome. BTW, I change oil (full synthetic) every 5,000km on both cars. JC will rubbish me for that but oil is cheap in comparison to engine repairs.

[@deanrhodenizer938]

@@p38arover22 I noticed that John didn't mention non-interference design engines.I expect they are becoming quite rare as the demand for greater efficiency progresses. Gone are the days of no secondary consequences from the failure of a timing belt or chain.

[@TB-LivingFree]

Great information as usual, thanks for sharing your impressive knowledge and insights

[@arokh72]

Well you certainly educated me, even though I can only afford $10k used, so the purchase price makes no difference between chain and belt. When I think of the so called superiority of chain driven engines, I just think of the chain issue of early VE Commodores, and the $1500, at least, repair bill an acquaintance paid at the local mechanic. But I also recall the $900 I paid for a belt change in a Hyundai. What about plastic vs rubber components in engines. I was talking to my mechanic who told me a story of a customer of his with a VW Tourag and the systemic disintegration of the plastic "critical" components, including the water pump being plastic. He said it's a similar issue with the Navara he was working on the time. He did advise that with my low budget, and being on DSP, that I'd better off going for a Honda CRV or Toyota Rav 4, and avoiding most others, especially Mitsi and Nissan as they use Euro engines "full of plastic".

[@theairstig9164]

I’m not a fan of plastic on the head. The BMW N63 is a case study on what happens to plastic near the combustion chamber. Peugeot got into it in the early 2000s to mixed effect. Later OHC stuff from 2010 onwards almost always have plastic cam covers. Go figure

[@ProjectFairmont]

I prefer belts since it transmits less engine harmonics through the crank and valve-train. Plus it eliminates chain wear contribution to engine oil. I also like the idea of a pre-prescribed pro active maintenance approach with cam belts. Chain drives don’t have a replacement schedule until failure and perhaps a ruined engine. A cam in block with a corresponding short chain are forgiving to less than regular oil changes, not so much multi cam engines with tensioners. Nich zer gut. Regular oil changes on anything is important, but especially so on chain driven multi cam VVT motors. And always run a PCV oil separator on a direct injection engine.

[@SirNecro]

I think the big message here is service intervals. Not how long one is VS the other, but sticking to them. One thing is for sure, if your timing chain breaks during use due to neglect, it's going to do a lot more damage to the internals of your engine than if a belt snaps. Heavy small pieces of metal being thrown around your internals without constraints is going to be a bad news day. But buggered is buggered, so your results will only be marginally better if the belt snaps. Adhere to servicing intervals, because a $2000 service is cheaper than having to purchase a new car.

[@jeffk464]

I haven't heard of chains breaking. Only stretch and tensioner issues. Belts had to be replaced around 60,000miles to play it safe. This was routine maintenance and didn't cost much. If you need work done for the chain it's going to cost you a fortune. I'm not saying they never break sure don't think it's common

[@SirNecro]

@@jeffk464 We had a well known issue with the VZ - VE Commodore here in Aus where the chains were breaking. I have seen it happen in other cars as well. Neglect is usually the reason

[@Tk-ou9ec]

My old 1980 Chrysler V8 has a chain engine. When the camshaft was upgrade we decided to install a new chain just to be sure as the engine had done 230,000 kms so the condition of the old one was unknown? However the original seemed to run fine and was still very quiet.

[@MrDingaling007]

Liked the older Toyota engines with a belt and non-interference motor. Super easy and cheap to replace.

[@johnwade1095]

Efficiency is impaired by the compromises on timing.

[@MrDingaling007]

@@johnwade1095 Yes. But from a reliability and cheap and easy to maintain aspect it was great.

[@85therealdeal]

Yep. Love my 2E 1.3 motor! ~ 37 kw / litre !

[@johnwade1095]

I ain't arguing with that.

[@MrBrendanrex]

My old Hyundai with the 1.6 D4FB diesel engine is still going strong at 260,000 miles with the original timing chain. Other than one recent replacement clutch and two aux drive belts, nothing else on the engine has been replaced. That includes fuel injectors, EGR valve, turbo, DPF. Engine oil & filter changed at 10,000 mile intervals with top quality parts & fully synthetic oil. I notice that the latest version of engine has now changed from chain to belt.

[@markwilkinson3048]

Had a timing chain break on a VK Commodore at less than a 100K. Just saying folks. Yes I know why did I buy a Commodore. I was young and stupid.

[@daveamies5031]

I've has several cars i've put 150k+ km on, some had chains some had belts, neither were an issue both were reliable because I always serviced them following the service recommendations, it always amazes me how people refuse to service their car properly and then complain it's unreliable, or better said it's amazing (not) how regular servicing improves a cars reliability.

[@jean-marccolomar]

Hey John, I really like your explanation, you've just opened my eyes, thanks for that and in regard to the manscaped product already user and converted my son also. Now he has a partner!😁😁

[@glenwillson5073]

John doing the manscaped add with a straight face - self control right there!

[@PhilipBallGarry]

Ideally, gear driven. My Honda VFR800 (5th gen) had gear driven camshafts. Designing that engine almost broke Honda - early examples of the 750cc version had the infamous "chocolate camshafts" which caused a major recall due to an incorrect hardening process. But once that was sorted, that engine became known as an engineering masterpiece. Sadly, the gears were omitted in favour of a chain in later models to make room for the vtec system. In fairness though, there were no issues. Some folks didn't like the mechanical "whine" from the gear-driven versions but I liked it. It reminded me just what amazing engineering Honda had pulled off especially considering this package was wrapped inside a very compact motor.

[@mcmoose64]

I loved the gear whine on those old VFR Hondas .

[@theairstig9164]

The VF750 RC15 is the “early” engine you refer to. They have very little in common with a VFR anything

[@davidbrayshaw3529]

A VFR 800 with gear driven cams? Are you sure? If so, what years? I've never seen one without chain driven cams.

[@anthonyadverse4449]

In them good ol' days, even doing 100kms in your 20's era vehicle was still a day trip..

[@markcarli8259]

All good information and advice. Thanks.

[@jomikjomik]

Good Lord, just say it, timing belt is cheaper, and you could replace it yourself vs $1000-$1500 to take the engine out and replace the tensions and belts.

[@wrpaulw2063]

Depending on the car, belt replacement is a significant regular expense. For many years I had an Audi A4 with a cam belt. Replacement interval for this was 4 years, cost $1000 a time. How much do you think a timing chain would have added to the new car cost?

[@ghost307]

Probably around $250. I'd rather pay a little more upfront than have to evaluate a$1,000 expense at 100,000 miles.

[@peterharrington8450]

Hi John here's a bit of toung in cheek for you I own a 1936 Austin 7 not a timing belt or chain in site in the old girls nd the original timing gears still going so thay must be the best lets go back to them hehe thanx for following the facts and spreading really information

[@dan2304]

Fact/data based opinions are greatly appreciated. Such opinions are far too rare.

[@ericdolby1622]

Honda does great with both. Love that company

[@nickyl9040]

i had a ford p/u with the 300 cid that had the gear-to-gear relationship between the crank and camshaft. never had a problem with it ; I wish that ford still made the engine

[@gegwen7440]

The BMW you referred to was I think the 54 engine where the designer hated the buyers so decided to place the chain at the ‘back’ of the engine and made sure to get maximum pain by using a weak single jobbie instead of a duplex. Honda used gear driven cams on the legendary VFR that lasted forever and then some.

[@murrieteacher]

Changing a belt or a chain is a pig of a job. With a chain there is the added problem of a sealed envelope to keep the oil in. I would not be surprised if the cooling system had to be partially removed. There are some chains that can have the new chain attached to the old chain and threaded through, but they are rare. I am 77 years old and remember the frequent visits to the service centre for valve clearance adjustment and timing adjustment and points gap adjustment and brake adjustment. We had to change engine oil at 1000 miles, and gearbox and differential changes were about 5000 miles. My car had two paid accessories; a radio and a heater. I am so thankful that they do not build cars like they used to (or use to, depending which side of the Great Dividing Range you live at).

[@postersm7141]

Hell for that matter why not timing gears? Remember those. You’re spot on with your video.

[@garysmeltzer1933]

That was a very good vid John enjoyed the content Thx mate

[@SteveMuir]

I had a Yamaha 500 that jumped the chain on the double overhead engine. All 8 valves bent. Like you say, "Not a good look". Now have a VFR 800. Gear driven cams. No debate about chains vs belts on that model.

[@biastv1234]

A mate of mine worked at Holden as a mechanical engineer, the move away from belts to chain 8:34 was due to less energy required to turn a chain over a belt that requires constant energy to keep it tensioned

[@johnwade1095]

I think it was partly driven by the idea of 'no major service for the 1st 100k miles' - that's why Ford adopted them for the 3.0 V6 Duratec.

[@biastv1234]

@@johnwade1095 pretty true, at the time Holden/ ford/ Mitsubishi/Toyota in Australia had durability goals of 200000ks without major work ( starter motors and alternators are ok, a head gasket is not) . Gone are those days

[@johnwade1095]

@@biastv1234 It's our fault as customers for insisting on lowest price now, not lowest cost to own, and on governments for setting arbitrary fuel economy requirements which have f. all relevance to real world driving experience.

[@hdmccart6735]

I had an enjoyable evening about 20 years ago when my 1 Litre, 3 cylinder Hyundai decided to lose power in the middle of Perth's Narrows Bridge at 10:00pm. The night I learnt what an Interference Engine is...(cracking little car though..)

[@seanmcintyre3986]

Another small detail: Belts don't transmit crank harmonics to the valves, this aids air flow and can improve performance.

[@geneharrogate6911]

Driving 4 answers produced a video on this about two years ago if prefer a more fine grain explanation accompanied by infographics. Infographics Cadogan, thats the ticket, or at least a whiteboard. Shuffling A4 against a cutting mat has had its day.

[@paulg3336]

Up until 8 months ago I had a 1993 Mazda MX5. I bought it in 2000 with 77,000 km on it and sold it with 400,000 km. I replaced the cam belt every 100,000 at which age they still look like new even under magnification. With the exception of the original belt,which did look aged. I assume the later belts I fitted (Bosch) were the newer HSN material. Still have the used ones hanging in the shed

[@philspencelayh5464]

I've had both early chains were noisy but lasted forever. Then belt, quiet expensive to maintain with the odd catastrophic failure even more expensive. My current car has a completely silent chain, the manufacturer says no maintenance required and its 12 years old, runs like new

[@deanrhodenizer938]

Greetings from Canada. This might be the first time that I am in complete agreement with one of your videos. Since I generally let you know when I don’t agree, it seems appropriate to comment when I do agree. I am an engineer and also a senior citizen, but I am not a believer in the “good old days”. The ongoing improvements in materials and methods have enabled us to progress relentlessly down the road to getting more for less - that is more vehicle while consuming less resources for what is delivered. We have greater safety, performance, reliability, efficiency, longevity, convenience, comfort, etcetera along with lower emissions in ALL vehicles produced today compared to the past. Yes, there have been a few missteps along the way when new materials (timing belt materials as you mentioned) were tried that didn’t work as intended but corrections quickly followed. Switching gears... What do you think about an internal combustion engine with no camshaft at all? How about electronically controlling the opening/closing of valves? No need for belts or chains or elaborate mechanisms (e.g. VTEC, VANOS, etc.) to control valve timing at all. Additionally, no need for valve springs and the energy needed to compress them. We can hold a valve in any position we want magnetically.

[@mikefromvernon]

Chains Vs Belts I see as 6 of one half a dozen of the other. Chains are more robust but yes they need clean oil, they can stretch etc. A properly designed belt can go a long time, is quieter but need replacing every 60,000 to 100,000 miles according to google. Maintenance is key either way. I had a disposable 18 year old dodge neon that ran perfectly because I changed oil every 6 months when I did a tyre swap and of course did tranny etc as required. I live in a place that demands winter tyres. That car ran perfectly when I drove to the dealer to trade her in. Rust was doing her in.