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When to replace a timing belt

I have a 1997 Miata with only 28,000 miles. The dealer says because the car is so old, I need to replace the timing belt, even though it only has 28k on it. Can the material wear out because of age, or should I stick to the manual for replacing it?

Yes. Timing belts should also be replaced based on time. This is usually 6-8 years. So you’re way overdue.

Tester

I fully agree. Check with the owners manual. They have time intervals next to the mileage intervals. 16 years is long past.

Do what your owner’s manual says. If it gives a time, follow that advice. Rubber materials definitely deteriorate w/time independent of how much they are used. The engineers who designed the car now the material’s properties. And the consequences of not following their advice can prove to be expensive. I think on a lot of these cars the mileage recommendation is 60K, but those sold in Calif and Massachussetts for some reason are recommended to be changed at a higher mileage, 105K I think. I’m not sure if that’s because they used a different material in the belt or what exactly makes it different state to state. Ask your dealership if unsure. Your Mazda dealership would know for certain.

Do it this week. Don’t postpone the work. You have a fine car, and it will remain so if you change the timing belt before it breaks. Even though it is not an interference engine, the double overhead cam configuration can lead to valve damage immediately after belt failure.

If you still have the owner’s manual it will say something like 90K miles or 8 years whichever comes first. People focus on the miles number and ignore the years number. If you don’t have the owner’s manual you can research this on the – gates.com – web site.

If the Gates site shows you have an interference engine (I suspect you do) then if the belt breaks; the pistons hit a couple of values and lock up the motor. The damage is significant to several pistons and likely 4 to 8 valves. If you repair the motor figure about $3,000. If that is too much then you find a used motor from a junker somewhere and then you are talking about $2,000 to get the car running again.

You seem to be saying that the manual doesn’t have a time interval, just a mileage interval. Is that really the case? That would be pretty unusual.

Yes, replace it. I recommend replacement of any timing belt that’s 10 years old, and I live in a mild climate. Rubber deteriorates with age, and that little rubber belt keeps your engine running. When it breaks, the car stops where ever it is and will cost you 3 to 4 times to repair than if you replaced it as maintenance.

It doesn’t have an interference engine, I would take my chances. That goes against 90% of the advice you will get here, but if it was my money, thats what I would do.

My only rebuttal to oldtimer11, is that a belt snap rarely happens when it is convenient. I’ve recently seen timing belt snaps that happened on highways late at night while going 70 mpg in the fast lane. Or on a rainy Sunday on the way to church in their Sunday best.

It’s cheaper and more convenient to schedule it and get it done.

I’m with Busted on this one. We;re talking about a 12++ year old timing belt here. It’s long overdue. And might pop in the middle of the night in the center of the low rent district. Or in a snowstorm on a highway with heavy traffic and no shoulders.

15 year old car with 28,000 means this isn’t a daily driver. For a weekend fun car you might forgo a new timing belt; but I’d be doubly sure that this is not an interference engine.

The rubber might be old and rotten, due to age. Change it now.

remember what c and c say: The cheapskate always spends the most.

It is a 16 year old Mazda Miata that has averaged 1750 miles a year. He isn’t going anyplace in the dead of night or the depths of winter. I have never seen a road where 70 mph wouldnt let you coast to a safe place. Having an engine quit in the days of the cell phone has become a minor inconvenience.

I’ve had 2 timing belts break on me. One was a 1/2 mile from the house. The other was 15 miles away. In both cases we had to get a tow home.

So it isn’t like it’s a minor inconvenience (depending on what YOUR definition of minor is).

CapriRacer:
Just curious about the 2 belts that broke. Were you within your time and mileage schedule for them?

On a related note, a friend of mine is a mechanic at at Hyundai dealership. Hyundai used a 60,000 mile replacement schedule for many years. When talking to him about his experience with them, he said Hyundai’s 4-cylinder chewed up belts like crazy - many not making it to 60K. While Hyundai’s 6-cylinder engine was much easier on them - where they saw very little breakage and the belts looked brand new at 60K.

I have a '00 Camry V6 (non-interference, or also known as free wheeling, motor) and a timing belt did break. Reason, the water pump failed and took out the timing belt. My son was visiting friends in LI, NY and it was a major inconvenience.

The timing belt and water pump had been replaced on schedule about 18 months prior. The shop that did the original job in PA was very good about it and has stopped sourcing water pumps from the supplier that provided the defective pump. I got no refund from anyone and was out another $700 to have the job redone in LI. That was several years ago and all is fine since. Thank goodness it was a non-interference motor.