47 Cooling system parts are listed for the 2021 International LT, in 11 part types, covering both the 12.4L L6 DIESEL Turbocharged and the 14.9L L6 DIESEL Turbocharged. Each one has a brand, a manufacturer part number and notes that say where it fits.
On the 2021 International LT, the cooling system system keeps operating temperature in the narrow band the engine was designed for, from radiator and water pump to thermostat and hoses. 29 parts of the 47 listed are Coolant / Antifreeze (13 parts), Thermostat (10 parts) and Radiator (6 parts). The other 8 part types cover the remaining 18 parts.
The 2021 International LT was sold with both the 12.4L L6 DIESEL Turbocharged and the 14.9L L6 DIESEL Turbocharged. 22 parts fit every engine; the other 25 are engine-specific. Each part shows which engine(s) it fits.
13 brands supply cooling system parts for the 2021 International LT, led by PRESTONE (7 parts), GATES (7 parts) and MOTORAD (6 parts), plus 10 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 International LT. 6 parts have it, including PRESTONE AF3100 (Coolant / Antifreeze) and SPECTRA PREMIUM 20013560P (Radiator). Each part number opens a page with every vehicle that part fits.
Coolant / Antifreeze
Compatible With All Colors
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| PRESTONE Fits: all 2021 LT engines | AF3055 | 🇺🇸 US 🇨🇦 CA | Prime YellowAll Vehicles | View on Amazon |
Economy
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| PRESTONE Popular Fits: all 2021 LT engines | AF3100 | 🇺🇸 US 🇨🇦 CA | Prime Yellow - All VehiclesExtended Life | View on Amazon |
| VALVOLINE Fits: all 2021 LT engines | 719009 | 🇺🇸 US 🇨🇦 CA | Multi-Vehicle Yellow1 Gallon | View on Amazon |
Heavy Duty
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| VALVOLINE Popular Fits: all 2021 LT engines | ZXG051 | 🇺🇸 US 🇨🇦 CA | G05 Yellow1 Gallon | View on Amazon |
| PEAK Fits: all 2021 LT engines | FCA1GAL | 🇺🇸 US 🇨🇦 CA | Fleet Charge1 Gallon | View on Amazon |
| PEAK Fits: all 2021 LT engines | FXA1GAL | 🇺🇸 US 🇨🇦 CA | Final Charge Global1 Gallon | View on Amazon |
| PRESTONE Fits: all 2021 LT engines | AFC10000 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Command ESi PrechargedPurple | View on Amazon |
| PRESTONE Fits: all 2021 LT engines | AFC13000 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Command COR-Guard Nitrite Free-Noat Extended Life CoolantRed | View on Amazon |
| PRESTONE Fits: all 2021 LT engines | AFC12100 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Command Nitrite Free Extended Life CoolantYellow Nitrite Free OAT | View on Amazon |
| VALVOLINE Fits: all 2021 LT engines | 846439 | 🇺🇸 US 🇨🇦 CA | HD Nitrite Free Extended Life Yellow1 Gallon | View on Amazon |
Premium
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| PRESTONE Popular Fits: all 2021 LT engines | AF2100 | 🇺🇸 US 🇨🇦 CA | All Vehicles10yr/300k mi | View on Amazon |
| PRESTONE Fits: all 2021 LT engines | AFMAX | 🇺🇸 US 🇨🇦 CA | Max Universal1 Gallon | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| VALVOLINE Fits: all 2021 LT engines | ZX001 | 🇺🇸 US 🇨🇦 CA | Original Green1 Gallon | View on Amazon |
This table covers the engine coolants and antifreeze formulations specified for this cooling system. Typical signs include a rising temperature gauge, rusty or sludged coolant, or a heater that blows cold. Use the chemistry named in the notes. Mixing silicate, OAT and HOAT formulas can gel in the radiator.
13 Coolant / Antifreeze parts are listed for the 2021 International LT, from PRESTONE, VALVOLINE and PEAK. PRESTONE AF3100 carries the "Popular" badge. All of them fit every engine offered in the 2021 LT.
The Compatible With All Colors section lists 1 option from PRESTONE — grouped under the catalog's "Compatible With All Colors" designation — the notes column spells out what sets them apart. PRESTONE AF3055 is listed in this group.
In the Economy grade, PRESTONE and VALVOLINE supply 2 parts: the catalog's value-priced group. A representative part number is PRESTONE AF3100.
The Heavy Duty section lists 7 options from PRESTONE, VALVOLINE and PEAK — rated for severe service. VALVOLINE ZXG051 is listed in this group.
The Premium section lists 2 options from PRESTONE — a step above OE specification in materials, tolerances or warranty terms. PRESTONE AF2100 is listed in this group.
The Standard Replacement section lists 1 option from VALVOLINE — built to original-equipment specification. VALVOLINE ZX001 is listed in this group.
Coolant Filter
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| DONALDSON Fits: 14.9L L6 DIESEL Turbocharged | P550867 | 🇲🇽 MX | Outer Diameter: 93 mm (3.66")Length: 147 mm (5.79") | View on Amazon |
| HASTINGS / BALDWIN Fits: 12.4L L6 DIESEL Turbocharged | LOPRI | 🇺🇸 US 🇨🇦 CA | View on Amazon |
This table covers the Coolant filters. Typical signs include restricted flow — long cranking, weak airflow, or dirty fluid after a short interval. Seat the new filter so it cannot bypass, and use the grade the notes call for.
2 Coolant Filter parts are listed for the 2021 International LT, from DONALDSON and HASTINGS / BALDWIN.
Listed part numbers: DONALDSON P550867 and HASTINGS / BALDWIN LOPRI.
Coolant Reservoir
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| DORMAN Fits: all 2021 LT engines | 6035247 | 🇺🇸 US 🇨🇦 CA | View on Amazon | |
| GPD Fits: 12.4L L6 DIESEL Turbocharged | 2421013 | 🇺🇸 US 🇨🇦 CA | View on Amazon | |
| GPD Fits: 14.9L L6 DIESEL Turbocharged | 2421012 | 🇺🇸 US 🇨🇦 CA | View on Amazon |
This table covers the overflow / expansion tanks that hold extra coolant.
3 Coolant Reservoir parts for the 2021 International LT come from 2 brands — GPD and DORMAN. 1 part fits every engine; the other 2 are engine-specific.
Listed part numbers: DORMAN 6035247, GPD 2421013 and GPD 2421012.
Coolant Reservoir Cap
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GATES Fits: all 2021 LT engines | 31405 | 🇺🇸 US 🇨🇦 CA | OE Type | View on Amazon |
| MOTORAD Fits: all 2021 LT engines | T39 | 🇺🇸 US 🇨🇦 CA | Standard | View on Amazon |
This table covers the caps on the overflow / expansion tank. Typical signs include a leak at the neck, a cap that will not hold pressure, or a missing tether. Match the pressure rating or thread in the notes — radiator, reservoir and fuel caps are not interchangeable.
2 Coolant Reservoir Cap parts for the 2021 International LT come from 2 brands — GATES and MOTORAD. Every part fits both the 12.4L L6 DIESEL Turbocharged and the 14.9L L6 DIESEL Turbocharged.
This group includes GATES 31405 and MOTORAD T39.
Cooling System Tester Adapter
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GATES Fits: 12.4L L6 DIESEL Turbocharged | 31379 | 🇺🇸 US 🇨🇦 CA | Cooling System PressureRadiator Cap | View on Amazon |
| GATES Fits: 12.4L L6 DIESEL Turbocharged | 31410 | 🇺🇸 US 🇨🇦 CA | Cooling System Pressure | View on Amazon |
This table covers the adapters used to pressure-test this cooling system.
GATES supplies both parts for the 2021 International LT.
Listed part numbers: GATES 31379 and GATES 31410.
Hose Clamp
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| DORMAN Fits: all 2021 LT engines | 9044000 | 🇺🇸 US 🇨🇦 CA | 1.75" DiameterCoolant | View on Amazon |
This table covers the Hose clamps.
One part is listed for the 2021 International LT — DORMAN 9044000.
Intercooler
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GPD Fits: all 2021 LT engines | 2711621 | 🇺🇸 US 🇨🇦 CA | with Original Equipment (OE) # 2516097C91 | View on Amazon |
This table covers the intercoolers that cool turbo or supercharger charge air.
One part is listed for the 2021 International LT — GPD 2711621.
Intercooler Air Hose / Pipe
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| CONTINENTAL Fits: 12.4L L6 DIESEL Turbocharged | 57504 | 🇺🇸 US 🇨🇦 CA | Convoluted Charge Air | View on Amazon |
| CONTINENTAL Fits: 12.4L L6 DIESEL Turbocharged | 57513 | 🇺🇸 US 🇨🇦 CA | Convoluted Charge Air | View on Amazon |
| GATES Fits: 12.4L L6 DIESEL Turbocharged | 26200 | 🇺🇸 US 🇨🇦 CA | Turbocharger Hose (Ring-Retained)Straight Hose | View on Amazon |
| GATES Fits: 12.4L L6 DIESEL Turbocharged | 26203 | 🇺🇸 US 🇨🇦 CA | Turbocharger Hose (Ring-Retained)4" x 6" (110 psi) | View on Amazon |
| GATES Fits: 14.9L L6 DIESEL Turbocharged | 26204 | 🇺🇸 US 🇨🇦 CA | Turbocharger Hose (Ring-Retained)4" x 8" (110 psi) | View on Amazon |
This table covers the Intercooler Air Hose pipes.
5 Intercooler Air Hose / Pipe parts are listed for the 2021 International LT, from GATES and CONTINENTAL.
Listed part numbers: CONTINENTAL 57504, CONTINENTAL 57513 and GATES 26200, plus the other parts above.
Radiator
Economy
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GPD Fits: all 2021 LT engines | 9282773 | 🇺🇸 US 🇨🇦 CA | with 34 In Core Heightwithout Frame | View on Amazon |
| GPD Fits: all 2021 LT engines | 9282774 | 🇺🇸 US 🇨🇦 CA | with Original Equipment (OE) # 2516107C91with 34 In Core Height | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| SPECTRA PREMIUM Popular Fits: all 2021 LT engines | 20013560P | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Aluminum Core with Plastic Tanks | View on Amazon |
| OSC Fits: 14.9L L6 DIESEL Turbocharged | HD9631 | 🇺🇸 US 🇨🇦 CA | without Frame | View on Amazon |
| OSC Fits: 14.9L L6 DIESEL Turbocharged | HD9633 | 🇺🇸 US 🇨🇦 CA | with Frame | View on Amazon |
| SPECTRA PREMIUM Fits: all 2021 LT engines | 20013560 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Aluminum Core / Aluminum Tank | View on Amazon |
This table covers the radiators that dump engine heat to airflow through the core. Typical signs include overheating in traffic, a wet core, or coolant that disappears with no puddle. Replace the cap if it cannot hold the rated pressure, and bleed the system after the swap.
6 Radiator parts are listed for the 2021 International LT, from GPD, SPECTRA PREMIUM and OSC. SPECTRA PREMIUM 20013560P carries the "Popular" badge. 4 parts fit every engine; the other 2 are engine-specific.
Economy: 2 parts, from GPD. A representative part number is GPD 9282773.
The Standard Replacement section: 4 options from SPECTRA PREMIUM and OSC. SPECTRA PREMIUM 20013560P is listed in this group.
This group includes SPECTRA PREMIUM 20013560P, GPD 9282773 and GPD 9282774 and the remaining parts above.
Thermostat
Heavy Duty
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GATES Popular Fits: 14.9L L6 DIESEL Turbocharged | 34148 | 🇺🇸 US 🇨🇦 CA | Heavy-Duty | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| MOTORAD Popular Fits: 14.9L L6 DIESEL Turbocharged | 406190 | 🇺🇸 US 🇨🇦 CA | Includes Seal | View on Amazon |
| CALORSTAT Fits: 14.9L L6 DIESEL Turbocharged | THS1910582 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | PerformanceDoes Not Include Seal | View on Amazon |
| CALORSTAT Fits: 14.9L L6 DIESEL Turbocharged | THS1910588 | 🇺🇸 US 🇨🇦 CA | Does not include seal | View on Amazon |
| MOTORAD Fits: 14.9L L6 DIESEL Turbocharged | 15199 | 🇺🇸 US 🇨🇦 CA | Heavy Duty190 Degrees F, Includes Seal, For Engine Coolant System | View on Amazon |
| MOTORAD Fits: 14.9L L6 DIESEL Turbocharged | 406160 | 🇺🇸 US 🇨🇦 CA | Includes Seal | View on Amazon |
| MOTORAD Fits: 14.9L L6 DIESEL Turbocharged | 407825 | 🇺🇸 US 🇨🇦 CA | 225 Degrees Ffor Engine Oil Cooler System | View on Amazon |
| MOTORAD Fits: 14.9L L6 DIESEL Turbocharged | 406180 | 🇺🇸 US 🇨🇦 CA | Includes Seal | View on Amazon |
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| CALORSTAT Fits: 12.4L L6 DIESEL Turbocharged | THS1910582 | 🇺🇸 US 🇨🇦 CA | PerformanceDoes Not Include Seal | View on Amazon |
| CALORSTAT Fits: 12.4L L6 DIESEL Turbocharged | THS1910588 | 🇺🇸 US 🇨🇦 CA | Does not include seal | View on Amazon |
This table covers the thermostats that open the coolant circuit at the specified temperature. Typical signs include slow warm-up, a gauge that climbs in traffic, or heat that never quite arrives. Replace the housing gasket with the thermostat and bleed the system so a trapped air pocket does not cook the new part.
10 Thermostat parts for the 2021 International LT come from 3 brands — MOTORAD, CALORSTAT and GATES. The "Popular" part is GATES 34148.
Heavy Duty: 1 part, from GATES. A representative part number is GATES 34148.
Standard Replacement: 7 parts, from MOTORAD and CALORSTAT. A representative part number is MOTORAD 406190.
2 further parts sit outside the graded sections, with the same engine-level match.
Thermostat / Thermostat Housing / Water Outlet Seal
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| DORMAN Fits: 14.9L L6 DIESEL Turbocharged | 6745003G | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Housing to Flange | View on Amazon |
| DORMAN Fits: 14.9L L6 DIESEL Turbocharged | 6745008G | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Housing to Cylinder Head | View on Amazon |
This table covers the seals at the thermostat housing and water outlet. Typical signs include a wet housing, a drip after sitting, or fluid flung off a rotating shaft. Fix the surface the seal rides on. A new seal on a grooved shaft will leak again.
DORMAN supplies both parts for the 2021 International LT.
Part numbers include DORMAN 6745003G and DORMAN 6745008G.
Buying Cooling System Parts for a 2021 International LT
On this vehicle, the cooling system system keeps operating temperature in the narrow band the engine was designed for, from radiator and water pump to thermostat and hoses.
- Match the engine first. Some cooling system parts fit every engine; others are 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 thermostat and refill with fresh coolant whenever you change a water pump or radiator; original hoses on an older vehicle are on borrowed time.
- Cross-reference the manufacturer part number against your old part or a service-manual listing.
Start with the largest groups on this page: Coolant / Antifreeze and Thermostat .
Frequently Asked Questions
How many cooling system parts fit the 2021 International LT?
Our catalog currently lists 47 cooling system parts for the 2021 International LT across 11 subcategories and 13 brands, covering both the 12.4L L6 DIESEL Turbocharged and the 14.9L L6 DIESEL Turbocharged. Each part is matched to the engine(s) it fits.
Do cooling system parts differ between 2021 International LT engines?
Some do. 22 parts fit every engine; the other 25 are engine-specific. Each row (and the filter at the top) shows which. 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 cooling system problems on a 2021 International LT?
Common symptoms include a rising temperature gauge in traffic, sweet-smelling steam, crusty deposits around hose clamps, or a heater that blows cold. 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 thermostat and refill with fresh coolant whenever you change a water pump or radiator; original hoses on an older vehicle are on borrowed time.
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 International LT 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 International LT?
First match the engine — each row shows which engine(s) the part fits. Then replace coolant with the exact specification the manufacturer calls for — mixing chemistries can gel and block small passages. The notes column carries position and trim qualifiers where they apply.
Other Parts for the 2021 International LT
Cooling System Parts for Other International LT Years
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