Car companies tend to find a good thing that works, and then change it. WHY?! Ford…I’m looking at you.
@keith I suppose so. I often wonder about those legendary engines that seem to just keep going. Like those 80’s Mercedes diesel sedans. When I was in highschool I knew a few kids driving them with over 300K on the clock.
I just wish a company would embrace simplicity. I dont care about the latest technology. I want the car to go down the road for 200K like its a joke, and when something breaks I want it to be accessible in the engine bay. BAH!!! HUMBUG!!!
“Car companies tend to find a good thing that works, and then change it. WHY?!”
For those Benz guys out there, and those who’ve worked on them frequently
Replacing the tried and true 112/113 engine with the 272/273 wasn’t too smart
Replacing the tried and true 722.6 5 speed at with the 722.9 7 speed at wasn’t too smart
So its settled. Belts are stupid. As I suspected.
You keep a vehicle 400k-500k miles then a timing chain is going to cost you more then a timing belt. Chains do NOT last for ever. They do require replacing (but usually after 250k miles). Timing chains don’t have to break to cause damage. They stretch over time and can slip a tooth. With an interference engine that’s the same as a timing belt breaking - engine is toast. Timing chains are a lot more involved to replace because they need to be lubed.
But I will concede that MOST people don’t keep vehicles over 300k miles like I do. So for MOST people a timing chain is probably better since they’ll never own it long enough to need it replaced.
I have a timing belt in my 2005 Accord V6 and it does not bother me that after 7 years of ownership I had to pay $800 for a new belt and a few other of the usual items. It is planned maintenance, and I’m not worried about it. I believe Honda still uses a timing belt in their 6 cylinder engines.
There’s a performance advantage using a timing belt. The belt weighs considerably less than a chain. Since it rotates with the engine, the weight of the belt doesn’t impart at much inertial force against the engine during acceleration as a heavier chain would. It’s the same idea why lower weight magnesium tires are used for sports and racing cars. Anytime you can lower the rotational mass, you’ll get better acceleration performance. How big the difference though, belt to chain, that I’m not sure. But you would at least in theory expect a lower measured 0-60 mph time interval with a timing belt than a chain.
If a manufacturer could come up with a timing belt arrangement where replacing it was a 15 minute job requiring no special tools I think timing belts could make a comeback. The problem is that what’s usually required now for a timing belt job, it takes 4 hours even for a skilled mechanic with all the tools. After the seemingly bizarre arrangement of timing belt covers are removed, then the engine has to be supported with a special tool while the engine mount is removed. After which the timing belt, idlers, and water pump have to be replaced. Even if the water pump and the idlers are working fine. Then you somehow have to reinstall the engine mount, but that can be quite time consuming if the engine has shifted position even slightly.
So I think what we need is a better timing belt routing scheme. One that would allow a DIY’er a procedure that the changing of the timing belt was not much more difficult than changing a serpentine belt. Or if the owner wasn’t a DIY’er, that a mechanic could do it in 15 minutes and charge less than $100 for the whole job, parts and labor.
Edit: I wonder if Formula 1 race cars use belts or chains?
There's a performance advantage using a timing belt. The belt weighs considerably less than a chain.
I’d be very surprised if it’s more then .1%.
I wouldn’t want to pay to have all the chains, guides and tensioners replaced on this engine
The owner’s jaw will drop, and he will start balling up, when he receives the estimate
He will fall on his knees and beg for mercy
@GeorgeSanJose: I am not completely up to speed on it, but I believe Formula 1 engines have used pneumatically operated valves for years now. Presumably this eliminates the need for any mechanical linkage. I have a memory of the McLaren Mercedes cars at Melbourne in the late nineties, where one or both of them had to pit to recharge the air in the system. At one point they were experimenting with magnetic actuators, but I don’t think anything ever came of it.
@db4690: Am I seeing an additional sprocket shaft to connect the crankshaft chain to each cam chain? And what is that lower chain for?
Looks like the engine has 2 balance shafts
The lowest chain seems to connect the crank to the oil pump . . . that would be my guess
But what’s the sprocket directly above the crank . . . idler, perhaps?
“I believe Formula 1 engines have used pneumatically operated valves for years now. Presumably this eliminates the need for any mechanical linkage.”
I think these simply replaced the wire springs with pneumatic “springs.” You still have cams pushing the valves open. This eliminated valve spring breakage.
If chains are so much better than belts, why does Harley Davidson use a belt to drive the rear wheel of its motorcycles while my Honda uses a chain that requires frequent adjustment and maintenance?
Typical over-engineered european BS. Haha I know that will anger some people, but hey, thats my opinion
@Fender1325
Don’t speak too soon . . .
GM has the LY7 3.6 liter V6, which is just as overengineered. It also has multiple chains, tensioners, guides, etc.
And let’s not forget the 4.0 liter Ford overhead cam V6, which has 3 chains, one of which is on the back side
The domestics are just as guilty of “over-engineered BS”
Please don’t take this the wrong way
I’m just explaining that all manufacturers, all countries, etc., are guilty of overengineering
True. Lots of people with a plain old family hauling Explorer have been told that one of the 3 timing chain tensioners has failed, and unfortunately since it’s the one at the back the engine will have to be removed to repair it.
Don’t forget the Chevy 3.4 DOHC ( I think) of the 90’s that had both a timing belt and a timing chain. The Dodge/Chrysler 2.7 that has multiple chains and a water pump inside driven by the primary chain.
At the dawn of the timing belt era timing belts were quite simple and cheap to replace. Ask anyone who had a Pinto or a Vega how hard the timing belts were to replace.
No offense taken at all. It seems generally the euro stuff is over engineered but domestic is catching right up to that status apparently.
What I find troubling is that these feats of engineering don’t feel like they’re accomplishing much. I wish one could say yeah they’re getting more and more complex but their gas mileage has quadrupled. As I said earlier my 1950 2 ton cadillac got 20 mpg highway apparently. I’ve seen early 90’s cars that returned mpg in the 40’s. And we know certain engine designs were known to regularly get 2 and 300k miles of life. So here we are over 20 years since then. AND…?
Magnetic actuation is still being worked on, and I suspect will eventually be common. It’s a good challenge getting the valves to open/close at the right times. It takes a good deal of power to move these things thousands of times per second. With a belt or chain there is a physical connection between them ensuring they all work together, though it’s still a good trick having springs that consistently do their jobs quickly and reliably. I’m always amazed that modern engines can get all these parts working together so perfectly.
@Fender1325
“What I find troubling is that these feats of engineering don’t feel like they’re accomplishing much.”
I have to agree with you on that
If one manufacturer has a dohc V6 driven with 1 single timing chain . . . why does another manufacturer feel they need 3 chains to do the same thing?
I recall my '79 Honda had a belt which if I had ever thought of replacing it, seems like it would have been a half hour job for a shade tree mechanic. LOL, I used to slip the belt of the camshaft pulley to try different valve timings, mostly advanced by one tooth, just to see how the torque curve changed (though I didn’t think of it in similar words). Those were the more carefree days for me, indeed!
I think one reason why car makers went to the belt was because that way they could do away with push rods, which often, in themselves, caused trouble, but mostly they just often “ticked.”
I just watched a Youtube video about commercials for the brand new 1964 Fords. They boasted of engine coolant that only needed to be changed every 2 years and wheel bearings that could go up to 24,000 miles before needing to be serviced. Cadillacs and Buicks in the 50’s had power windows operated by brake fluid that would leak out and peel the paint off your car. What was the oil change interval back then, 1000 miles? Tell me again how much better those cars were?