21615589 Cap | Genuine Volvo Penta Part

🔧 Product Description

A pressure-rated filler cap used on the closed-cooling expansion tank of Volvo Penta V8 petrol marine engines.

🚤 Compatibility

Typically suits:

• Volvo Penta 3.0GXiC-J
• Volvo Penta 3.0GXi-J

⚙️ Key Features

• Closed-cooling pressure cap
• Seals expansion tank 21614836
• Controls cooling-system pressure and venting
• Heat- and coolant-resistant sealing element
• Correct filler-neck engagement

🔌 Function

The cap seals the tank and maintains the specified pressure so coolant boiling point and recovery operation remain controlled.

⚠️ Common Signs of Failure

• Coolant leaking around the cap
• Pressure not retained
• Hardened or damaged seal
• Cap difficult to lock or remove
• Repeated coolant discharge at normal temperature

🛠️ Service Notes

• Clean and inspect the seating face on the housing as well as the cap — most leaks past a cap are the seat or the seal rather than the cap body
• Renew any separate O-ring or gasket that goes with the cap, and lubricate rubber seals lightly with clean oil or grease so they slide home instead of rolling or tearing
• Do not over-tighten a cap into a plastic or aluminium housing; it seals on its gasket or O-ring, not on force, and stripped threads mean a much bigger repair
• Where a cap blanks a port during a repair, keep it fitted right up to the moment of assembly so nothing enters the opening
• Check the cap is fully home and that any retaining clip, lanyard or locking tab is secure before returning the boat to service

🔄 Supersession & Cross Reference

OEM / Related Numbers

• 21614836 - Expansion tank
• 21614847 - Cover
• 21614855 - Bracket
• 21614860 - Spill plate

📦 Condition

• Genuine Volvo Penta part
• Brand new
• Supplied in original or equivalent packaging