Radiator Caps & Coolant Reservoir Caps

Radiator cap costs vary depending on the equipment type and pressure rating. For heavy equipment such as Caterpillar or Komatsu machinery, caps typically range from a few dollars to upward of $30 or more. Commercial truck applications may fall in a similar range. Login-based pricing is available through Radiator Supply House for trade and business customers seeking volume or account pricing.

You should never remove the radiator cap or coolant reservoir cap while the engine is hot or still running. The cooling system operates under pressure, and removing the cap prematurely can cause a sudden release of scalding steam and coolant. Always allow the engine to cool completely — typically at least 30–60 minutes after shutdown — before opening any cooling system component.

The correct pressure rating depends on your specific equipment make and model. Most heavy equipment and commercial trucks use caps rated between 7 PSI and 20 PSI. Always reference your OEM service manual or the specification stamped on the original cap. Using an incorrect pressure rating can lead to coolant loss, overheating, or cooling system damage. Contact Radiator Supply House with your model number for guidance.

A radiator cap seals the main radiator filler neck and regulates system pressure via a pressure-relief valve, while a coolant reservoir cap seals the overflow or expansion tank. Both work together to maintain proper coolant levels and pressure. In many modern systems, the reservoir cap also serves a pressure-regulating role. Using the correct cap type for each location is essential for proper cooling system function.

Radiator caps on heavy equipment should be inspected during every major service interval and replaced if the rubber seal is cracked, worn, or the cap fails a pressure test. As a general guideline, caps are recommended for replacement every two years or 200,000 miles on commercial vehicles. Failing caps can cause coolant leaks, pressure loss, and overheating — making regular inspection critical for high-use machinery.

Yes. Radiator Supply House stocks radiator caps and cooling components specifically compatible with major heavy equipment brands including Caterpillar, Komatsu, John Deere, Freightliner, Peterbilt, and more. Products are available for a wide range of models including construction, mining, GenSet, and commercial trucking applications. Login to your account or contact support to verify part compatibility for your specific machine model.