2008 Mazda3 2.3L Timing Chain and Other Belts

Vehicle has about 75,000 miles. I have been told (but can’t confirm) that this vehicle has a timing chain and is a non-interference engine. Does the timing chain need to be replaced; and, is it a non-interference engine? If the timing chain should break will it cause any serious/fatal engine damage? If the belts look good (no cracks, no squeaks) should they be changed? Any other suggestions for preventive maintenance? Vehicle has been very reliable and maintenance free except routine oil changes, tires, and battery.

Timing chains don’t need replacement like the timing belts. You should flush the radiator and brakes. I would do the serpentine belt due to age. Battery needs to be replaced. Tires and brake pads should be inspected for wear a.

The Gates web site doesn’t show a timing belt, so I’d say you have a timing chain. It should last the life of the car. My understanding is that it’ll get noisy if it does start to wear out sometime in the future.

As for the serpentine belt, you’re at the point where it’s reasonable to replace it if you’d like. You’d probably get another few years out of it if you don’t.

Timing chains outlast belts by a long ways, but don’t last forever. There are non-invasive ways to determine a worn chain, but they typically stretch, not snap. And you typically see signs of strecthed chain after 150,000 to 200,000 miles if the oil is changed on time. Drive belts and serpentine belts are suspect after 5 years. New belts using EPDM cannot be judged by visual inspection. A wear guide can be used. http://www.gates.com/products/automotive/tools-and-sales-aids/belt-wear-diagnosis/epdm-belt-wear-diagnosis

Much depends on if it has a single row chain or double row chain. Double row chains will pretty much last longer than the engine unless the engine sits unused for a length of time, like a year or so. The timing chain is lubricated by a spray of oil from the oil pump so if it isn’t kept oiled, it will begin to rust, and then when started, it will break.

I have less faith in single row chains, but they seem to be lasting upwards of 200k or so. Most cars have gone to single row chains.

I kept the original serpentine belt in my 02 Saturn for 10 years and 220k miles. Just didn’t think about it. One day I was looking at it and it was so shiny that it looked like it was about to melt, so I replaced it.

Don’t flush the radiator. Just check your owners manual for the service schedule and then drain and refill, just like you would do for your oil. Same for the transmission fluid. Especially do not use a chemical flush in your cooling system. Your coolant has corrosion inhibitors in it so if you flush, even with plain water, you introduce minerals that will shorten the life of those inhibitors. Better to leave a little of the old coolant in there, it is harmless and it wont be that much. Just like an oil change, you leave a little of the old oil in the engine, but it doesn’t hurt anything as long as you keep up the oil change schedule. Same for the radiator and the transmission.

True that most dealers don’t flush any more. They drain the radiator and fill it. Antifreeze lasts 5 year or 100k miles, which ever comes first. Brake fluid 3 years. I use Distilled water when I flush my cooling system and for topping off my batteries. It contains no minerals to contaminate my system.

It’s not the timing chain that fails, but timing chain tensioner/guide.


Over time the plastic material wears off the tensioner/guide causing the timing chain to become slack. Then along with the timing chain stretching over time the timing chain can jump time.

Fortunately, the engine isn’t an interference engine. So if the timing chain fails no engine damage will occur.

The statement that dealers/shops don’t flush cooling systems is false. This method is faster with less mess and exchanges all the coolant. Even the coolant in the block.

The next time you go to the dealer, ask them if they use a coolant exchange machine. And they’ll say yes, or point it out to you. And ask them if they use a transmission fluid exchange machine, and they’ll point that out too.