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The Cummins Thermostat Assembly 4974580 is a genuine cooling system component designed for multiple Cummins engine families, ensuring precise temperature regulation and reliable engine performance.
✅ Compatible Cummins Engines:
ISL Series: ISL8.9, ISL9 – commonly used in medium-duty trucks (Freightliner M2, International TerraStar), school buses, and coaches.
ISC Series: ISC8.3 – widely applied in trucks, buses, RVs, and industrial equipment.
ISB Series: ISB5.9, ISB6.7 – popular in buses, industrial machinery, and trucks.
QS Industrial Series: QSL9 and QSC8.3 – for generators, construction machinery, and marine engines.
Features & Benefits:
OEM Cummins quality, direct fit replacement
Maintains optimal engine operating temperature
Prevents overheating and improves engine efficiency
Suitable for on-road, off-road, and industrial applications
This 4974580 thermostat assembly is a critical Cummins spare part for maintaining the cooling system and ensuring long engine life.
The most common variants are:
4974580 (82°C / 180°F): This is a very common standard rating.
4974581 (88°C / 190°F): A higher temperature thermostat used in many applications.
4974582 (82°C / 180°F): Another common 180°F variant, often with minor revisions.
The safest way to confirm this part is correct for your specific engine is to use your Engine Serial Number (ESN).
Locate your ESN: It is on the engine's dataplate.
Provide the ESN to your parts supplier: An authorized Cummins distributor or a reputable online database can use the ESN to confirm:
That 4974580 (or one of its variants like 4974581) is the correct part.
The exact temperature rating required.
The ISB, ISC, and ISL engines are the backbone of the North American and European medium-duty truck and bus markets.
This is arguably the single largest category. If you see a full-size school bus in North America, there's a very high chance it has one of these engines.
IC Bus (Navistar): Their CE-series and RE-series buses are overwhelmingly powered by Cummins ISB and ISC engines.
Blue Bird: Many Blue Bird Vision and All American models use Cummins ISB and ISL engines.
Thomas Built Buses: The Saf-T-Liner HDX and other models frequently feature the Cummins ISL.
These are the workhorses you see every day making deliveries and supporting construction.
Freightliner: The M2 106 model is famously paired with the Cummins ISB and ISL engines.
International (Navistar): The DuraStar and TerraStar models are common applications for the ISB and ISC engines.
Peterbilt: The Model 325 and Model 330 are often spec'd with Cummins ISL engines.
Kenworth: The T370 model is a frequent application.
Cummins ISB and ISL engines are extremely popular in larger Class A and Class C motorhomes due to their reliability and power.
Companies like: Tiffin, Newmar, Winnebago, Fleetwood, and many others use these Cummins engines as a premium power option.
Gillig: Many Gillig low-floor transit buses use the Cummins ISL.
New Flyer: A major transit bus manufacturer that offers Cummins engines.
Motorcoaches: Various shuttle buses and smaller intercity coaches.
Fire & Rescue: Many custom fire engine chassis use these reliable engines.
Ambulances: Medium-duty ambulance bodies are often built on International or Freightliner chassis with Cummins power.
