Things to Know About Engine Timing Belt from the service professionals at Carr Subaru in Beaverton, OR

In order to run smoothly and powerfully, the various parts of your vehicle's engine need to be in perfect sync. The pistons connected to the crankshaft need to sync with the valves connected to the camshaft (or camshafts), and it all must move in perfect harmony. To accomplish this, internal combustion engines feature a timing system that physically links them together, so they can't come out of sync! At least, not unless this system fails. And some designs are more durable than others. On this page, we'll go into a little more detail about what timing systems you can find on modern Subaru cars and what maintenance is required to keep them running like clockwork.

Gears like these form the basis of basic engine timing systems.

3. Timing Gears: The Old-School

The original design for the timing system was pretty simple on older engines: a gear attached to the end of the crankshaft would mesh with another gear on the end of the camshaft. This linked their motion together so they would always be in the same position relative to one another. That made sure that the valves opened at the right time to add fuel to the engine and let exhaust out.

However, strong gears can be expensive to manufacture, and this design limited the size and design of the engines. Also, drivers would tend to complain about the whining noise made by the gears meshing together. For these reasons, the industry moved on quickly to timing chains and eventually timing belts.

With piston damage and a broken valve, this engine has probably suffered timing system failure.

2. Timing Chains: The Reliable One

To allow engines to be built larger and in more exotic layouts, the engine timing chain was developed. Now, the gears on the camshafts didn't need to be linked directly to the gear on the crankshaft -- instead, a chain much like a heavy-duty version of a 10-speed bicycle chain would link all the various gears together, and keep them in sync. On modern cars, this chain is usually hidden behind a thick cover and lubricated with oil, so the engine runs smooth and quiet. Best of all, modern timing chains are designed to be maintenance-free and last the entire life of the engine!

Mechanic's hand removes the timing belt from an engine.

1. Timing Belts: Be Careful

To keep things even quieter and less expensive to manufacture, a new timing system was developed that used not a clunky, metal timing chain but a notched, rubberized belt instead. Changing a timing belt is much faster, cheaper and easier than a timing chain or gears, and it's lightweight and quieter too. But there is one caveat: rubber belts are known to occasionally snap as they wear out. If the timing belt goes in your car, the engine could completely destroy itself! As the various components of your engine come out of sync, this can cause pistons to strike the open valves, almost certainly ruining the engine inside. That's why, if your vehicle's engine is kept in time with a timing belt, it's important to know when it needs to be replaced!

On the 2019 lineup of Subaru vehicles, all of them now use reliable timing chains for maintenance-free convenience -- all except the track-tuned Subaru WRX STI. Because that car is designed for maximum performance, and because enthusiasts love to tinker with, tune and maintain their own vehicles, the 2019 Subaru WRX STI features a timing belt. That makes it a cinch to replace in a hurry at the track if you know your way around the engine bay, but remember: A broken timing belt spells disaster for any modern Subaru engine! Be sure to have this part regularly replaced on your WRX STI. Subaru recommends replacing the timing belt on a 2019 Subaru WRX STI every 96,000 miles.

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Carr Subaru

11635 SW Canyon Rd
Directions Beaverton, OR 97005

  • Sales: (503) 672-3370
  • Service: (866) 460-0188
  • Parts: (888) 627-4707
  1. Carr Subaru

    11635 SW Canyon Rd
    Beaverton, OR 97005

    • Sales: (877) 271-4560

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