Parts for your 2018 Mazda 3-Timing belt kit

2018 Mazda 3 timing-belt-kit: not required — here’s why

The 2018 Mazda 3 (BN/BM series) does not use a timing belt, so a timing-belt-kit is not relevant to this vehicle. Both the SKYACTIV-G 2.0L and 2.5L petrol engines, and the SKYACTIV-D 2.2L diesel where fitted, run a timing chain. That means there’s no scheduled timing-belt replacement and no belt kit to install.

Technical references back this up: the Mazda Workshop Manual (SKYACTIV-G 2.0/2.5, Engine Mechanical – Timing Chain) specifies a chain-driven valvetrain, the BN/BM owner’s maintenance schedule contains no timing belt replacement item, aftermarket catalogues such as the Gates Australia Timing Belt Guide and the Dayco Australia catalogue list the 2018 Mazda 3 engines as “chain drive” with no timing belt. Trade data sources (Autodata/Haynes) likewise describe a timing chain for these engines.

Why did Mazda go with a chain? A timing chain runs in engine oil, is designed for long service life, and typically doesn’t have the fixed replacement intervals associated with rubber timing belts. For owners, that reduces major service costs and avoids the need for a belt kit (belt, tensioner, idlers and often a water pump) at set kilometre milestones.

While there’s no timing-belt-kit to worry about, the timing chain still appreciates good care. Clean oil is critical: dirty or degraded oil can accelerate chain, tensioner and guide wear. Using the correct oil grade (Mazda commonly specifies low-viscosity oils such as 0W-20 for SKYACTIV-G) and sticking to time-and-kilometre service intervals helps the chain live a quiet, long life.

• Listen for cold-start rattles or persistent ticking from the front of the engine, unusual noises warrant an inspection of the chain, guides and tensioner.
• Scan for cam/crank correlation fault codes if a check-engine light appears.
• Inspect the auxiliary (serpentine) drive belt, tensioner and idlers, the water pump on these engines is not driven by a timing belt, so it’s serviced independently.

For 2018 Mazda 3 owners, the upshot is simple: no timing-belt-kit is fitted or required. Keep up with quality oil and filter changes, and have a technician check for noises or leaks at regular services to keep the chain system healthy for the long haul.

Popular questions on 2018 Mazda 3 timing-belt-kit

Does the 2018 Mazda 3 have a timing belt or a chain?
The 2018 Mazda 3 uses a timing chain across its SKYACTIV-G 2.0L and 2.5L petrol engines (and SKYACTIV-D 2.2L where sold). There is no timing belt, so a timing-belt-kit isn’t applicable.

When should the timing chain be replaced on a 2018 Mazda 3?
There’s no set replacement interval. The chain is designed to last the life of the engine. Replacement is only considered if there are symptoms such as rattle on start-up, correlation fault codes, or confirmed wear to the chain, guides or tensioner.

What should be serviced instead of a timing-belt-kit?
Focus on regular oil and filter changes with the correct spec oil, as well as periodic checks of the auxiliary drive belt, belt tensioner, idlers and the water pump for leaks or noise. These items are separate from the timing system and are serviced on condition.