1/4" NPT To 3/8" Barb Straight Barb Hose Fitting (Billet Oil Filler, Maxi Pump)

These 1/4″ NPT to 3/8″ barbed hose fittings are designed for aircooled Volkswagen engines where smaller threaded ports need to be connected to 3/8″ breather or oil hoses. Commonly used with billet oil fillers and Maxi oil pump fittings, these adaptors provide a clean and reliable solution for custom engine builds and upgraded oil systems.

Each fitting features a 1/4″ NPT tapered thread, allowing it to screw securely into billet oil filler necks, breather outlets, or Maxi pump ports. The tapered design ensures a tight, leak-resistant seal when installed with thread sealant. The 3/8″ hose barb provides a firm grip on the hose, maintaining a secure connection under pressure and preventing leaks or hose movement.

These fittings are particularly suited to breather systems where controlled crankcase ventilation is essential. By allowing 3/8″ hose to be used on smaller threaded ports, they help maintain efficient airflow and reduce internal engine pressure, which can otherwise lead to oil leaks or reduced engine performance. They are also widely used on Maxi oil pumps where auxiliary outlets require connection to external oil lines.

For installation, you may also require 3/8″ breather or oil hose, hose clamps, and thread sealant. Depending on your setup, these fittings can be used alongside breather boxes, oil catch tanks, or external oil system components.

Sold separately, these fittings provide a reliable connection for both inlet and outlet applications.

Vehicle Fitment

Aircooled VW:

• Beetle (1949–1979) – All engines
• Beetle Cabriolet (1949–1979)
• T2 Split Bus (1950–1967)
• T2 Bay Window (1968–1979)
• T25 / T3 Aircooled (1979–1983)
• Karmann Ghia (1955–1974)
• Type 3 (1961–1973)
• Trekker (1968–1983)
• Buggy / Baja (Type 1 based, 1949–1979)

Watercooled VW:

• T25 / T3 Watercooled (1983–1992) – when fitted with custom breather or oil systems

Key Features

• 1/4″ NPT male thread (tapered for secure sealing)
• 3/8″ hose barb for breather or oil hose connection
• Ideal for billet oil filler outlets and Maxi oil pump fittings
• Supports efficient crankcase ventilation
• Suitable for custom and performance oil systems
• Durable, leak-resistant construction
• Supplied separately (1 fitting)