This page lists 20 belt drive parts for the 2021 Mazda 3, across 3 part types, covering the 2.5L L4 Turbocharged engine. Every part shows its brand, manufacturer part number and fitment notes.
The belt drive system on the 2021 Mazda 3 spins the accessories — serpentine and V-belts, tensioners, idlers and pulleys. All 20 listed parts are Belt (13 parts), Belt Tensioner (6 parts) and Belt Tensioner Adjuster (1 part).
Every part on this page is matched to the 2.5L L4 Turbocharged — the only engine offered in the 2021 Mazda 3.
The most listed brands for 2021 Mazda 3 belt drive parts are CONTINENTAL (5 parts), GATES (5 parts) and DAYCO (3 parts), plus 5 more brands. Quality grades include Standard Replacement, Economy and Kit.
5 parts on this 2021 Mazda 3 page carry a "Popular" badge — the source catalog's flag for options frequently chosen for this vehicle — including BANDO 6PK965 (Belt) and GATES 90K39390 (Belt Tensioner). Click any part number to see every vehicle that part fits.
Belt
Economy
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| CONTINENTAL | 380K6MK | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Mileage MakerSerpentine | View on Amazon |
| FVP | 380K6 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Multi V-BeltSerpentine | View on Amazon |
| GATES | K060380 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Micro-V | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| BANDO Popular | 6PK965 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Rib Quantity: 6Inch Number: 380K6 | View on Amazon |
| DAYCO Popular | 5060382 | 🇺🇸 US 🇨🇦 CA | Serpentine | View on Amazon |
| GATES Popular | K030315SF | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Premium OE Stretch Fit Micro-V BeltRequires Installation Tool | View on Amazon |
| ACDELCO | 3K315SF | 🇺🇸 US 🇨🇦 CA | Professional / GoldStretch Fit | View on Amazon |
| ACDELCO | 6K380 | 🇺🇸 US 🇨🇦 CA | Professional / GoldSerpentine | View on Amazon |
| CONTINENTAL | 4030315S | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Multi V-Belt Stretch Belt | View on Amazon |
| CONTINENTAL | 4030317S | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Multi V-Belt Stretch Belt | View on Amazon |
| CONTINENTAL | 4060380 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Multi V-BeltSerpentine | View on Amazon |
| DAYCO | 3PK794EE | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | ELA® Stretch BeltSerpentine | View on Amazon |
| GATES | K030311SF | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Premium OE Stretch Fit Micro-V Belt | View on Amazon |
This table covers the serpentine and accessory belts that drive the front accessories. Typical signs include squeal on cold start, cracks across the ribs, or glazing on the back of the belt. A new belt on a worn tensioner will squeal within weeks — spin the idlers by hand while the belt is off.
13 Belt parts are listed for the 2021 Mazda 3, from CONTINENTAL, GATES, DAYCO and 3 other brands. BANDO 6PK965 carries the "Popular" badge.
In the Economy grade, CONTINENTAL, FVP and GATES supply 3 parts: the catalog's value-priced group. A representative part number is CONTINENTAL 380K6MK.
The Standard Replacement section lists 10 options from CONTINENTAL, DAYCO, GATES and 2 other brands — built to original-equipment specification. BANDO 6PK965 is listed in this group.
Belt Tensioner
Kit
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GATES Popular | 90K39390 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | KitIncludes: 2 Belts, Tensioner | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| LITENS Popular | 999630A | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Serpentine | View on Amazon |
| ACDELCO | 39390 | 🇺🇸 US 🇨🇦 CA | Professional / Gold | View on Amazon |
| CONTINENTAL | 49858 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Multi-V | View on Amazon |
| DAYCO | 89710 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | View on Amazon | |
| GATES | 39390 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Serpentine | View on Amazon |
This table covers the automatic tensioners that hold belt tension. Typical signs include belt flutter, a chirp that returns after a new belt, or a damper that no longer holds the arm. Replace the tensioner with the belt at higher mileage; the labor overlaps almost entirely.
6 Belt Tensioner parts for the 2021 Mazda 3 come from 5 brands — GATES, LITENS, ACDELCO and 2 other brands. The "Popular" part is GATES 90K39390.
The Kit section lists 1 option from GATES — grouped under the catalog's "Kit" designation — the notes column spells out what sets them apart. GATES 90K39390 is listed in this group.
Standard Replacement: 5 parts, from LITENS, ACDELCO, CONTINENTAL and 2 other brands. A representative part number is LITENS 999630A.
Part numbers include GATES 90K39390, LITENS 999630A and ACDELCO 39390, among others listed above.
Belt Tensioner Adjuster
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| SKP | SK90K39390 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | View on Amazon |
This table covers the Belt Tensioner adjusters.
This group shows a single part: SKP SK90K39390.
Buying Belt Drive Parts for a 2021 Mazda 3
On this vehicle, the belt drive system spins the accessories — serpentine and V-belts, tensioners, idlers and pulleys.
- Confirm you have the 2.5L L4 Turbocharged engine — every part on this page is matched to it.
- Read the notes on each row for position, trim and spec qualifiers before you order.
- Where labor overlaps, replace the tensioner and idler pulleys with any belt at higher mileage — the labor overlaps almost entirely.
- Cross-reference the manufacturer part number against your old part or a service-manual listing.
Start with the largest groups on this page: Belt and Belt Tensioner .
Frequently Asked Questions
How many belt drive parts fit the 2021 Mazda 3?
Our catalog currently lists 20 belt drive parts for the 2021 Mazda 3 across 3 subcategories and 8 brands, covering the 2.5L L4 Turbocharged engine. Each part is matched to the engine(s) it fits.
What are the signs of belt drive problems on a 2021 Mazda 3?
Common symptoms include squealing on cold start, a belt that shows cracking or glazing, or an accessory that slows under load. If you notice any of these, identify the affected subcategory above and cross-reference the part numbers listed.
What should I replace at the same time?
Where labor overlaps, replace the tensioner and idler pulleys with any belt at higher mileage — the labor overlaps almost entirely.
What do the market flags (US, CA, MX) on each part mean?
They show the market for which the manufacturer published application data for that part — where the vehicle was first sold, not where the part was made. If your 2021 Mazda 3 was originally sold in the US, the safest choice is a part marked for the US market.
How do I make sure a part fits my 2021 Mazda 3?
Every part on this page is matched to the 2.5L L4 Turbocharged engine. Then a new belt on a worn tensioner will squeal within weeks — check tensioner damping and idler bearings while the belt is off. The notes column carries position and trim qualifiers where they apply.
Other Parts for the 2021 Mazda 3
Belt Drive Parts for Other Mazda 3 Years
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Manufacturer names, model designations and part numbers are used for identification and fitment reference only. AutoFactsDB is an independent catalog and is not affiliated with, endorsed by, or sponsored by any vehicle manufacturer displayed on this page.