This page lists 33 belt drive parts for the 2021 Freightliner 122SD, across 3 part types, covering all 3 engine options (12.8L L6 DIESEL Turbocharged, 14.9L L6 DIESEL Turbocharged and 15.6L DIESEL). Every part shows its brand, manufacturer part number and fitment notes.
On the 2021 Freightliner 122SD, the belt drive system spins the accessories — serpentine and V-belts, tensioners, idlers and pulleys. All 33 listed parts are Belt (18 parts), Belt Tensioner (9 parts) and Idler Pulley (6 parts).
The 2021 Freightliner 122SD was sold with 3 engines. Every part on this page is engine-specific. Each part shows which engine(s) it fits.
6 brands supply belt drive parts for the 2021 Freightliner 122SD, led by GATES (12 parts), DAYCO (7 parts) and CONTINENTAL (6 parts), plus 3 more brands. Quality grades include Standard Replacement, Heavy Duty and Economy.
A "Popular" badge means the source catalog flagged the part as frequently chosen for the 2021 Freightliner 122SD. 6 parts have it, including GATES K100643HD (Belt) and GATES 38667 (Belt Tensioner). Each part number opens a page with every vehicle that part fits.
Belt
Heavy Duty
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GATES Popular Fits: 12.8L L6 DIESEL Turbocharged, 15.6L DIESEL | K100643HD | 🇺🇸 US 🇨🇦 CA | Fleet Runner Heavy Duty Micro-V | View on Amazon |
| GATES Popular Fits: 12.8L L6 DIESEL Turbocharged | K081055HD | 🇺🇸 US 🇨🇦 CA | Fleet Runner Heavy Duty Micro-V | View on Amazon |
| GATES Popular Fits: 14.9L L6 DIESEL Turbocharged | K060658HD | 🇺🇸 US 🇨🇦 CA | Fleet Runner Heavy Duty Micro-V | View on Amazon |
| GATES Popular Fits: 15.6L DIESEL | K081062HD | 🇺🇸 US 🇨🇦 CA | Fleet Runner Heavy Duty Micro-V | View on Amazon |
| ACDELCO Fits: 14.9L L6 DIESEL Turbocharged | K060658HD | 🇺🇸 US 🇨🇦 CA | Professional / GoldHeavy Duty | View on Amazon |
| CONTINENTAL Fits: 12.8L L6 DIESEL Turbocharged | 4081055X | 🇺🇸 US 🇨🇦 CA | Extreme Duty Multi V-BeltSerpentine | View on Amazon |
| CONTINENTAL Fits: 12.8L L6 DIESEL Turbocharged, 15.6L DIESEL | 4100642FX | 🇺🇸 US 🇨🇦 CA | Extreme Duty Multi V-BeltSerpentine | View on Amazon |
| CONTINENTAL Fits: 15.6L DIESEL | 4081063X | 🇺🇸 US 🇨🇦 CA | Extreme Duty Multi V-BeltSerpentine | View on Amazon |
| GATES Fits: 14.9L L6 DIESEL Turbocharged | K120866HD | 🇺🇸 US 🇨🇦 CA | Fleet Runner Heavy Duty Micro-V | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GATES Popular Fits: 14.9L L6 DIESEL Turbocharged | K060658 | 🇺🇸 US 🇨🇦 CA | Micro-V | View on Amazon |
| ACDELCO Fits: 14.9L L6 DIESEL Turbocharged | 6K658 | 🇺🇸 US 🇨🇦 CA | Professional / GoldSerpentine | View on Amazon |
| CONTINENTAL Fits: 12.8L L6 DIESEL Turbocharged | 4081055 | 🇺🇸 US 🇨🇦 CA | Multi V-BeltSerpentine | View on Amazon |
| DAYCO Fits: 12.8L L6 DIESEL Turbocharged, 15.6L DIESEL | 5100640 | 🇺🇸 US 🇨🇦 CA | Serpentine | View on Amazon |
| DAYCO Fits: 12.8L L6 DIESEL Turbocharged | 5081055 | 🇺🇸 US 🇨🇦 CA | SerpentineGold Label Industrial Poly-Ribbed Belt | View on Amazon |
| DAYCO Fits: 14.9L L6 DIESEL Turbocharged | 5060658 | 🇺🇸 US 🇨🇦 CA | Serpentine | View on Amazon |
| DAYCO Fits: 14.9L L6 DIESEL Turbocharged | 5120865 | 🇺🇸 US 🇨🇦 CA | Serpentine | View on Amazon |
| DAYCO Fits: 15.6L DIESEL | 5081063 | 🇺🇸 US 🇨🇦 CA | Serpentine | View on Amazon |
| GATES Fits: 15.6L DIESEL | K081062 | 🇺🇸 US 🇨🇦 CA | Micro-V | 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.
18 Belt parts for the 2021 Freightliner 122SD come from 4 brands — GATES, DAYCO, CONTINENTAL and 1 other brand. The "Popular" part is GATES K100643HD.
In the Heavy Duty grade, GATES, CONTINENTAL and ACDELCO supply 9 parts: rated for severe service. A representative part number is GATES K100643HD.
In the Standard Replacement grade, DAYCO, GATES, ACDELCO and 1 other brand supply 9 parts: built to original-equipment specification. A representative part number is GATES K060658.
Belt Tensioner
Economy
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| SKP Fits: 12.8L L6 DIESEL Turbocharged, 15.6L DIESEL | SK38667 | 🇺🇸 US 🇨🇦 CA | Fan | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GATES Popular Fits: 12.8L L6 DIESEL Turbocharged, 15.6L DIESEL | 38667 | 🇺🇸 US 🇨🇦 CA | Fleet Runner | View on Amazon |
| CONTINENTAL Fits: 12.8L L6 DIESEL Turbocharged, 15.6L DIESEL | 49603 | 🇺🇸 US 🇨🇦 CA | Multi-V | View on Amazon |
| DAYCO Fits: 12.8L L6 DIESEL Turbocharged, 15.6L DIESEL | 89947 | 🇺🇸 US 🇨🇦 CA | Replaces 89498 and 89498A | View on Amazon |
| LITENS Fits: 12.8L L6 DIESEL Turbocharged, 15.6L DIESEL | 910585A | 🇺🇸 US 🇨🇦 CA | Fan | View on Amazon |
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GATES Fits: 14.9L L6 DIESEL Turbocharged | 38587 | 🇺🇸 US 🇨🇦 CA | Fleet Runner | View on Amazon |
| GATES Fits: 14.9L L6 DIESEL Turbocharged | 38610 | 🇺🇸 US 🇨🇦 CA | Fleet Runner | View on Amazon |
| LITENS Fits: 14.9L L6 DIESEL Turbocharged | 910074A | 🇺🇸 US 🇨🇦 CA | View on Amazon | |
| LITENS Fits: 14.9L L6 DIESEL Turbocharged | 910568A | 🇺🇸 US 🇨🇦 CA | Air Conditioning | 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.
9 Belt Tensioner parts are listed for the 2021 Freightliner 122SD, from GATES, LITENS, SKP and 2 other brands. GATES 38667 carries the "Popular" badge.
In the Economy grade, SKP supplies 1 part: the catalog's value-priced group. A representative part number is SKP SK38667.
The Standard Replacement section: 4 options from GATES, CONTINENTAL, DAYCO and 1 other brand. GATES 38667 is listed in this group.
4 ungrouped parts are not assigned to a grade, with the same engine-level match.
Part numbers include GATES 38667, SKP SK38667 and CONTINENTAL 49603, among others listed above.
Idler Pulley
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| CONTINENTAL Fits: 12.8L L6 DIESEL Turbocharged, 15.6L DIESEL | 50073 | 🇺🇸 US 🇨🇦 CA | Smooth | View on Amazon |
| DAYCO Fits: 12.8L L6 DIESEL Turbocharged, 15.6L DIESEL | 89124 | 🇺🇸 US 🇨🇦 CA | Smooth | View on Amazon |
| GATES Fits: 12.8L L6 DIESEL Turbocharged, 15.6L DIESEL | 36742 | 🇺🇸 US 🇨🇦 CA | Smooth | View on Amazon |
| GATES Fits: 14.9L L6 DIESEL Turbocharged | 36223 | 🇺🇸 US 🇨🇦 CA | GroovedFlanged | View on Amazon |
| LITENS Fits: 12.8L L6 DIESEL Turbocharged, 15.6L DIESEL | 900657A | 🇺🇸 US 🇨🇦 CA | Smooth | View on Amazon |
| LITENS Fits: 14.9L L6 DIESEL Turbocharged | 900376A | 🇺🇸 US 🇨🇦 CA | Grooved | View on Amazon |
This table covers the idler pulleys the belt wraps around. Typical signs include a chirp that follows engine speed, or a pulley that feels rough or has play. Replace a noisy idler with the belt — the labor is already paid for.
6 Idler Pulley parts for the 2021 Freightliner 122SD come from 4 brands — GATES, LITENS, CONTINENTAL and 1 other brand.
Listed part numbers: CONTINENTAL 50073, DAYCO 89124 and GATES 36742, plus the other parts above.
Buying Belt Drive Parts for a 2021 Freightliner 122SD
On this vehicle, the belt drive system spins the accessories — serpentine and V-belts, tensioners, idlers and pulleys.
- Match the engine first. Every belt drive part here is engine-specific; each row shows which engine(s) it fits.
- 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 Freightliner 122SD?
Our catalog currently lists 33 belt drive parts for the 2021 Freightliner 122SD across 3 subcategories and 6 brands, covering all 3 engine options (12.8L L6 DIESEL Turbocharged, 14.9L L6 DIESEL Turbocharged and 15.6L DIESEL). Each part is matched to the engine(s) it fits.
Do belt drive parts differ between 2021 Freightliner 122SD engines?
Yes. Every belt drive part on this page is engine-specific. Each row shows which engine(s) it fits — use the filter at the top to hide the rest. If you're unsure which engine you have, check the emissions label under the hood or the 8th character of your VIN.
What are the signs of belt drive problems on a 2021 Freightliner 122SD?
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 Freightliner 122SD 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 Freightliner 122SD?
First match the engine — each row shows which engine(s) the part fits. 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 Freightliner 122SD
Belt Drive Parts for Other Freightliner 122SD Years
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