Coolant Pressure Testing / Purge Cap. Porsche 718 Boxster / 718 Cayman  ❭  C4108

Coolant Pressure Testing / Purge Cap – Essential Tool for Cooling System Diagnostics & Maintenance

This coolant pressure testing and purge cap is purpose-built for the Porsche 718 Boxster and 718 Cayman, allowing technicians to accurately test, diagnose and bleed the cooling system. It replaces the standard coolant reservoir cap during servicing and enables direct connection to pressure testers, vacuum purge systems and coolant refilling equipment.

The 718’s turbocharged flat-four engine operates under high thermal load, and its cooling system relies on precise pressure levels to maintain performance and prevent overheating. This specialised cap ensures that coolant pressure tests are accurate and reliable, helping technicians detect leaks, verify system integrity and properly purge air after coolant replacement.

What This Coolant Pressure / Purge Cap Does

This tool allows you to:

• Connect a pressure testing system to check for leaks
• Verify pressure stability across hoses, radiators, gaskets and coolant tank
• Support vacuum filling and coolant purging after service
• Identify failing components early, such as water pumps or coolant leaks
• Ensure complete air removal, preventing hot spots and overheating
• Aid in diagnosing coolant loss, pressure drop or overheating problems

It is an essential tool for workshop-level cooling system maintenance on the 718 platform.

Why Coolant Systems Fail on the Porsche 718

The 718 Boxster/Cayman cooling system may develop faults caused by:

• Age-related hose deterioration
• Weak or failing coolant reservoir caps losing pressure
• Small leaks in radiators, water pumps or O-rings
• Air pockets trapped after coolant service
• Thermal expansion stress from spirited driving or track use
• Clogged or restricted coolant passages
• Faulty expansion tank fittings

A pressure test using a proper purge/testing cap is the fastest way to locate these issues before significant engine damage occurs.

Why You Should Use or Replace the Coolant Test/Purge Cap

A high-quality cap ensures:

• Accurate coolant pressure readings
• Fast detection of hidden leaks
• Proper bleeding of the cooling system after service
• Reliable seal under pressure, unlike worn standard caps
• Reduced risk of overheating or coolant boil-over
• Professional-quality servicing for Porsche 718 engines

Replacement is recommended when a cap becomes worn, cracked, or fails to hold pressure during diagnostic procedures.