I have a 1994 Dodge Intrepid with 3.3 liter mill. My trusty Chilton’s manual states that the 3.3 has a timing chain, not a belt (the 3.5 liter has a belt). Chilton’s gives detailed instructions on when the 3.5 liter timing belt must be checked (60K) and when replaced (106K) but says absolutely nothing about checking or changing my 3.3 liter timing chain. Their picture of the timing chain shows a brawny, seemingly indestructible device.
I grew up thinking that timing chains would last as long as the car and that they demanded absolutely no maintenance, not even a visual check. And I always assumed that the industry’s substitution of the flimsy, non-metallic belt was simply a device to further gouge the public.
Am I wrong about any of these things? Should I be concerned with the state of my impressive looking timing chain?
Normally you ignore the timing chain unless you start getting reason to wonder about it - like if something starts to get noisy.
Most engines with chains do not require any attention to the chain (Mike will disagree). My experience has been that by the time the chain is loose enough to need attention (300K to 500K miles) the engine needs to be rebuilt anyway.
There are exceptions. There are some designs with plastic tensioners that can fail at the 150K range and cause major engine damage.
You Are Basically Correct. However The Flimsy Belts Aren’t On There Just To Gouge The Unsuspecting Public.
My wife’s Intrepid has close to 300,000 miles and the timing chain is still going strong. They run in engine oil and as long as the owner keeps the engine oil relatively clean, most cars’ timing chains will last as long as practicable or as long as the car is still valuable.
Where I live (a drive a ton of miles) cars rust out long before a timing chain wears out.
I wrestled a timing belt into my 3.5L Intrepid (Great car, by the way) out in the driveway. I bought a couple of inexpensive special tools and made one tool to make the job easier, but I think that’s the last car with a timing belt, I’ll own.
You’re wise if you keep the chain vs. belt design in mind when shopping for a replacement car. The biggest problem with belts is that I’d guess the majority of owners that have them, don’t even know it, they break, leave them stranded, and turn the car into a ton and a half paper-weight.
The luck ones who know they’ve got a belt either get to keep replacing them or paying somebody to do it. The last three cars I’ve purchased all have chains ! On purpose !
CSA
Chains tend to last longer, but they also tend to be a little noisier and the whole system tends to be heavier than a belt system.
Most engines with chains do not require any attention to the chain (Mike will disagree).
Probably because you only keep your cars 100k miles. Try keeping them 300k miles…and you’ll end up replacing a chain. Every vehicle I’ve ever owned that had a chain…needed it replaced at about 250k miles.
No, I keep them to the 300K range. Maybe you are buying the wrong cars?
Every vehicle I’ve ever owned that had a chain…needed it replaced at about 250k miles.
How often did you change the oil?
If you have a timing chain, changing the oil on time should help it last longer. If you have a timing belt, you should still change the oil on time, but if you have oil gelling or sludging, it might lead to damage to a timing chain.
Chains generally last the life of the engine.
Designers went to belts with the proliferation of V6 engines with dual overhead cams. The chain works great with only a crankshaft and a camshaft ot two. Radii of the gears can be sufficient for a chain and it doesn;t have to travel through an inside bend.
With the advent of V6 engines with dual camshafts, chains would have to follow a convaluted path with small radii gears. The more the links have to articulate is the harder it is on a chain. And inside bends, necessary to provide sufficient “wrap” on small radii, don’t work with chains. Chains have too much mass, and they try to become a circle as they rotate, like the loop in a lariat.
In ahort, belts work better on V-style engines with dual overhead cams, and chains work fine on a single head where the number of cams is limited and the path not too convaluted.
And belts are cheaper for the manufacturer to use. They keep costs down. Well, actually, they transfer the costs. The manufacturer saves $5 and the consumer spends $260 every 60,000 miles.
BMW mastered the chain system for use with multiple camshafts.
I’ve replaced timing chains on engines with as low 120,000 miles on them. 2000 Dodge Dakota. Owner couldn’t figure out why the engine was a slug.
I had a Chevy 305 come in. I believe it was a 87 Caprice. Took that timing chain off without removing the gears!
Had a BMW come in. When the chain guides failed they fell at the bottom of the cover and caused the timing chain to jump off the crank gear. Bent valves.
Timing chains/guides don’t last forever. If they did, the parts stores wouldn’t sell replacement parts.
Tester
I think this is being looked at in two different ways. Saying that timing chains do not require regular attention could be seen as accurate. However, that doesn’t mean that they never require attention. At a quarter-million miles, you’re on borrowed time with every part of a car, and anything can fail. I think both of you can agree on that.
I’ve never had to replace or even needed to replace a timing chain on any of my cars and those cars all see way up into the 6 digits on mileage. Even my previous 87 Mercury still had a rock solid chain at the 420k miles mark and my prior Lincoln Mark (which has a chain about 6 feet long) had zero chain problems right up to the moment it became a total wreck.
Chains don’t die; they’re murdered by lack of regular oil changes. The same thing applies to rear drive chains on motorcycles which are exposed to the elements. It’s recommended that cycle chains be removed, cleaned in kerosene, and soaked in oil every 1000k miles. Few riders do this; they simply hose them down with aerosol chain lube. End result? Chains have a lifespan of 6k miles, maybe 10k if someone is running an expensive O-ring chain.
There were some problems with the fiber gear setups used way back when but those are ancient history and long gone.
Timing chains are no different. Those pins and rollers don’t last long with grit, sludge, or coked oil being the main lubricant, be it auto timing chain or cycle chain.
Not wrong at all. Wrong all the way.
There are two sides to many stories. There are lots and lots of timing chain stories, from Ford’s plastic sprocket teeth to the shores of Tripoli. The old V-8 engines used to wear out all the time up in the great white North. Can’t remember if I changed one that went bad in a Chevy small block. Pontiac, Ford and Chrysler products would go bad most often for my friends and me.
There weren’t many chain guides in those days. Centrifugal force would cause some of the wear. Soft metal would ruin the things too.
Cutting corners was done years ago. It wasn’t invented today.
Timing belts are a great way to reach up to those overhead camshafts. Some engines have four valves per cylinder, and a camshaft in the block on a V-6 would not have enough space for 24 lobes. With dual overhead cams, you would need five pounds of chain and the guides to go with them. It is sometimes a lot less expensive to use belts.
I do like the Ford V-8s with the SOHC and chains. There is just something about that mechanical stuff that appeals to us who were around when the 427 Ford DOHC engine showed up in car models. The engine was big enough to impress everybody. The front timing chain cover was huge and chrome too. It must have cost a fortune to own one of those engines.
The Ford 4.6 DOHC uses timing chains. The GM Northstar engine, DOHC uses timing chains. Timing belts are just a cheaper way to reach the top of the cylinder head, and they can convulute better than a chain, so you use idler pulleys, not chain guides.
The only car I ever replaced a chain on was a 1984 Impala with the 305 V8. It did not break, but got quite noisy. This car had cheap plastic gears, I believe, and we replaced them with a heavy duty double sprocket set. The oil was changed every 3000 miles, and the timing chain noise started at 156,000miles.
When my son finally sold the car at 300,000 miles the engine still ran perfectly.
Wrong. I’ve Never Replaced A Timing Chain. I’ve Never Even Had A Noisy Chain. I Change Oil Religiously At 5,000 Mile Intervals. However, These Are All American Cars.
CSA
" . . . but they [chains] also tend to be a little noisier . . . " That Sounds Right, But The Engines In My Vehicles With Timing Chains Are Quieter Or As Quiet As Those With Belts.
“and the whole system tends to be heavier than a belt system.” That’s it ? That’s the big disadvantage to a timing chain ? Saving the owner hundreds of dollars ( sometimes thousands ) and lost time in maintenance and repairs and the concern is a couple of extra pounds ?
Come to think of it, I’ll bet if I added up the weight of all the idlers (those puppies are heavy) and tensioners, sprockets, and components in my Caravan’s timing belt system, and I just replaced all of it, I’d bet that there’s not a hill of beans worth of difference, weight wise, between that and the chain system in my Intrepid, Bonneville or Impala. The golf balls in my trunk weigh more than either system.
CSA
Sounds Right, But Our Intrepid With 24v DOHC Has A Timing Chain System. The One With 300,000 Miles On It !
CSA