Expansion tank caps​ Radiator expansion tank cap for Land Rover Expansion tank sealing pressure cap OE MJA4440BA

Product Description:

Coolant expansion tank cover
OE NO.: MJA4440BA   PCD500030

Applicable vehicle type: For Land Rover

The coolant expansion tank cap serves as a critical sealing and pressure control component within the automotive cooling system, mounted atop the expansion tank (also termed the reservoir or coolant recovery tank). Through its integrated spring-loaded valve mechanism, it maintains stable internal pressure within the cooling system, prevents coolant boiling and leakage, and provides safe pressure relief during overpressurisation.

Installation Guidelines

• Clean the expansion tank opening to ensure no contaminants are present
• Align the threads, manually pre-tighten, then secure with a torque wrench to the specified torque (typically 12-20Nm)
• Verify the seal ring is correctly positioned without deformation or crushing

Fault Indicators

• Frequent coolant depletion: Inspect the cap seal integrity and pressure valve functionality
• Insufficient system pressure: May lead to boiling and overheating
• Failure to release excess pressure: May cause pipe rupture

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