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What is the difference between a timing belt and a serpentine belt on a Subaru?

A timing belt (or timing chain in newer Subarus) keeps the engine’s camshaft timing in sync with the crankshaft, while a serpentine belt powers external accessories such as the alternator, power steering pump, and air conditioning. Some Subaru engines still use timing belts, but many recent models rely on timing chains. The serpentine belt runs outside the engine and wears independently of the timing system.

In practice, this means that the timing belt/chain governs the critical timing of valve operation, whereas the serpentine belt simply keeps the accessories turning. If the timing belt or chain fails in an interference engine, serious engine damage can occur; a serpentine belt failure typically causes the car to lose charging, steering assist, and cooling/heating function—not immediate engine damage, but it can leave you stranded. Maintenance schedules and replacement costs vary by engine family, so the exact answer depends on your specific Subaru model and year.

Are Subarus still using timing belts or chains?

Subaru’s engine lineup has shifted toward timing chains for many newer engines, reducing the need for periodic belt replacement. However, some older engines and certain trims still use timing belts. The belt you have depends on the engine family (for example, older EJ-series engines used belts, while many newer FA/FB-series engines use chains). Always verify your exact engine type in the owner's manual or by checking the engine code on the engine itself.

Engine families and model years

In broad terms, the traditional timing belt was common in older Subarus (EJ engines), while many current Subarus (with FA/FB engines) use timing chains. The serpentine belt is present across most if not all Subaru models to drive accessories, regardless of whether the engine uses a belt or chain for timing. When in doubt, consult your vehicle’s documentation or a dealer to confirm the belt type for your specific model year.

Key differences between timing belt and serpentine belt

Before digging into maintenance, here is a concise comparison of what each belt does and how it affects your Subaru.

Function: Timing belt (or chain) controls valve timing by linking the crankshaft to the camshaft(s); serpentine belt drives accessories like the alternator, power steering, and A/C compressor.

Location and construction: Timing belts are internal to the engine (often rubber with fabric reinforcements and teeth); serpentine belts are external, single long belts routed around pulleys.

Impact on engine timing: A failure of the timing belt/chain can can cause timing to go out of sync, potentially damaging the engine on interference designs; serpentine belt failure does not affect timing directly.

Failure consequences: Timing belt/chain failure can lead to bent valves and severe engine damage in many Subarus; serpentine belt failure results in loss of electrical charging, steering assist, and cooling/heating function, potentially leaving you stranded.

Replacement and cost: Timing belts are more involved and often more expensive to replace (and may require other components like the water pump); serpentine belts are cheaper and quicker to replace, with separate labor intervals.

In short, the timing belt/chain is part of the engine’s timing mechanism, while the serpentine belt is a separate accessory drive belt. Knowing which type your Subaru uses is essential for proper maintenance planning.

Maintenance and replacement guidance for Subaru belts

The following guidance covers general practice and common intervals. Always consult your owner's manual for the exact schedule for your model and engine.

Timing belt (if your engine uses one): Replacement is typically recommended around 60,000–105,000 miles, depending on the model and year. Many Subarus with belt-driven timing fall into the 90,000–105,000 mile range, but some older models may require earlier service. When a timing belt is replaced, the water pump and related tensioners are often replaced at the same time.

Serpentine belt: Replacement is commonly recommended every 60,000–100,000 miles, depending on the belt material and operating conditions. Periodic inspection for cracks, fraying, glazing, and lost tension is advised.

Signs of wear: For timing belts, look for cracks, missing teeth, fraying, or glazing; for serpentine belts, watch for cracks, fraying, glazing, or squealing noises. A tense, properly routed belt with no cracks is a good sign, but any wear warrants replacement.

Related components: If you replace a timing belt on engines where the water pump is driven by the belt, plan to replace the pump and tensioners as part of the same service to avoid future labor charges.

Inspection cadence: Have both belts visually inspected during regular maintenance (often around every 30,000 miles) so early wear can be detected before a failure.

Proactive maintenance and using OEM or high-quality replacement parts will reduce the risk of unexpected belt failures and costly repairs in Subaru engines.

What to do if you’re unsure which belt your Subaru uses

Check your owner's manual or service booklet to confirm the belt type and replacement intervals for your exact model and year. If you’re still unsure, contact a Subaru dealer or a trusted mechanic with your VIN and engine code. They can quickly verify whether your engine uses a timing belt or chain and provide the correct maintenance plan.

Summary

The timing belt (or chain) and the serpentine belt serve different purposes in a Subaru: timing timing controls engine synchronization, while serpentine drives external accessories. Subarus increasingly rely on timing chains in newer engines, but some older models still use timing belts. Replacement needs, intervals, and potential consequences vary by engine family, so always verify your specific model-year details in the manual or with a dealer. Regular inspection and timely replacement of belts are key to preventing costly failures and keeping your Subaru running smoothly.

What year did Subaru get rid of the timing belt?

But most prior to 2012 or 2010. Will be a belt driven engine now the belt driven engines of late were the EJ. Series that includes but not limited to the EJ18 EJ20 EJ22 and EJ25.

How do I know if I need a timing belt or a serpentine belt?

Timing belts need to be replaced based on mileage recommendations, often between 60,000 and 100,000 miles, while serpentine belts can last longer but should be inspected regularly for signs of wear.

Are serpentine and timing belt the same?

No, serpentine and timing belts are not the same; they are two different belts with distinct functions, locations, and consequences of failure. The serpentine belt is on the outside of the engine and drives accessories like the alternator and power steering pump, while the timing belt is inside the engine and synchronizes the crankshaft and camshaft.

Feature	Serpentine Belt	Timing Belt
Function	Powers external engine accessories such as the alternator, power steering pump, and air conditioning compressor.	Synchronizes the internal engine components, specifically the crankshaft and camshaft, to control valve and piston movement.
Location	On the outside of the engine, easily visible, looping around several pulleys.	Deep inside the engine, protected by a cover.
Failure Consequence	Accessories stop working, which can make the car difficult or unsafe to drive, but the engine will likely continue to run for a while.	Can lead to severe internal engine damage or a complete engine failure, as the pistons can collide with the open valves.

Do all subarus need timing belt replacement?

Timing BELTS are recommended every 100k (105 to be more exact, as per Subaru), but chains do not have a regular interval. Chains are replaced when there's an issue with them.

Kevin Bennett

Company Owner

Kevin Bennet is the founder and owner of Kevin's Autos, a leading automotive service provider in Australia. With a deep commitment to customer satisfaction and years of industry expertise, Kevin uses his blog to answer the most common questions posed by his customers. From maintenance tips to troubleshooting advice, Kevin's articles are designed to empower drivers with the knowledge they need to keep their vehicles running smoothly and safely.