Engineered for 1994 through 2016 Ford F-250, F-350, F-450, F-550 Super Duty, OBS trucks, and Excursion models equipped with 7.3L, 6.0L, 6.4L, or 6.7L Powerstroke turbo diesel engines, this genuine Motorcraft OE Degas Bottle Reservoir Cap (9C3Z-8101-B / RS-527) regulates cooling system operating pressure. The degas cap maintains a constant 16 PSI seal to raise coolant boiling temperatures while venting overpressure to protect delicate system components.

Over years of severe thermal cycles, the internal spring mechanism and rubber seals inside factory caps weaken, lose calibration, or crack. A failing cap often vents prematurely at 8 to 10 PSI rather than the required 16 PSI, mimicking blown head gasket symptoms ("coolant puking" out the reservoir neck) or causing localized hot spots in the cylinder heads. Installing an authentic Motorcraft OEM cap restores proper pressure holding and prevents unexplained coolant loss.

Key Features & Benefits

• Genuine Ford Motorcraft Quality: Manufactured to strict OEM tolerances to ensure dependable pressure retention and an airtight, leak-free seal.
• Calibrated 16 PSI Pressure Valve: Features a stainless steel internal spring calibrated to hold precisely 16 PSI before venting excess pressure.
• Eliminates False Blown Head Gasket Symptoms: Solves premature reservoir puking and coolant burping caused by weak, tired aftermarket or original caps.
• Heavy-Duty Chemical-Resistant Seals: Molded automotive-grade rubber gasket resists drying, cracking, and chemical attack from traditional or modern OAT/HOAT coolants.
• Positive Click-Lock Retention: Designed with standard threading that clicks securely onto factory or direct-replacement aftermarket degas bottles.

Technical Specifications

• Manufacturer Part Number: 9C3Z-8101-B / 9C3Z8101B
• Motorcraft Part Number / SKU: RS-527 / RS527
• Superseded / Alternate Part Numbers: F6DZ-8100-A, 1W13-8101-AA, RS-103
• Pressure Rating: 16 PSI (Pounds Per Square Inch)
• Material Construction: Heat-Resistant Engineered Polymer with Stainless Steel Spring
• Cooling Reservoir Type: Pressurized Degas Bottle / Coolant Expansion Tank
• Core Requirement: None
• Warranty: Ford Motor Company 2-Year / Unlimited Mileage Warranty

Vehicle Fitment & Installation Notes

• 1994.5–2003 Ford F-250 / F-350 / Excursion – 7.3L Powerstroke Diesel
• 2003–2007 Ford F-250 / F-350 / F-450 / F-550 / Excursion – 6.0L Powerstroke Diesel
• 2008–2010 Ford F-250 / F-350 / F-450 / F-550 – 6.4L Powerstroke Diesel
• 2011–2016 Ford F-250 / F-350 / F-450 / F-550 – 6.7L Powerstroke Diesel (Primary High-Temp Cooling Circuit)
• Fitment Notice: Directly replaces the pressurized degas tank cap on all 1994–2016 Powerstroke applications. Note: On 2011–2016 6.7L dual-radiator platforms, this cap is engineered for the primary high-temperature degas bottle.
• Installation Tip: Thread the cap on until you feel firm engagement and it clicks into position. Check the reservoir neck for hairline cracks or plastic warping before installing a new cap to ensure a complete vacuum/pressure seal.