Dayco 5120858 serpentine belt for the 2010-2017 Kenworth T800 6-cylinder 14.9L, the 2015 T800 6-cylinder 10.8L and other vehicles carries engine power to the alternator, fan and water pump. The Dayco serpentine belt replaces a worn or failed belt on the engine's accessory drive.
- EPDM belt body with aramid reinforcement
- K-section profile with 12 straight ribs at standard rib depth
- Operating range of -45 F to 212 F (-42.7 C to 100 C)
- Made to SAE J1459 and SAE J2432 standards
Quick facts
- Part: Dayco 5120858 serpentine belt
- Fits: 2010-2017 Kenworth T800 6-cylinder 14.9L, the 2015 T800 6-cylinder 10.8L and other vehicles
- Position: Alternator, fan and water pump
- Material: EPDM, aramid reinforced
- Condition: New
Cracks across the ribs, fraying at the edges or a squeal at startup can mean the belt is worn. With the engine off and cool, look along the ribs for damage and for oil or coolant on the belt. A worn tensioner or pulley can wear a new belt the same way, so find what damaged the old one before you fit this belt.
Fits
The vehicles it fits include the 2010-2017 Kenworth T800 6-cylinder 14.9L, the 2018-2023 Peterbilt 567 6-cylinder 14.9L and the 2019-2023 Peterbilt 579 6-cylinder 14.9L.
Specifications
Fit and size
- Position: Alternator, fan and water pump
- Quantity per vehicle: 1
- Ribs: 12
Build and materials
- Material: EPDM, aramid reinforced
- Cross section: K-section
- Rib profile: straight rib
- Rib depth: standard
- Operating temperature: -45 F to 212 F (-42.7 C to 100 C)
- Standards: SAE J1459, SAE J2432
- Condition: New
In the box
One serpentine belt. Each of these trucks takes one belt.
Interchange: 25-120858 · 25-120858HD
12K858 · K120858HD · 12PK2180 · 12PK2185 · K120858 · 4120858 · 4120858X · 4120860
This part cross-references / interchanges with the following part numbers:
12K858, K120858HD, 12PK2180, 12PK2185, K120858, 4120858, 4120858X, 4120860, 25-120858, 25-120858HD, D84-1000-6122180
Frequently Asked Questions
Does the Dayco 5120858 serpentine belt fit the 2018-2023 Peterbilt 567 6-cylinder 14.9L?
Yes. The Dayco 5120858 fits the 2018-2023 Peterbilt 567 6-cylinder 14.9L and the 2019-2023 Peterbilt 579 6-cylinder 14.9L. For any other truck, look up your own in the "Vehicles it fits" section.
Is this Dayco drive belt made of EPDM?
Yes. The Dayco 5120858 is made of EPDM with aramid reinforcement. It is a K-section belt with 12 straight ribs.
What temperatures can this Dayco fan belt run in?
This serpentine belt operates from -45 F to 212 F (-42.7 C to 100 C).
What does a worn serpentine belt look like?
Cracks across the ribs, fraying along the edges or glazed, shiny ribs can mean the belt is worn. You can look for these with the engine off and cool.
Which SAE standards apply to this serpentine belt?
This belt is made to SAE J1459 and SAE J2432.
