CSF 3139 Radiator

OE-Style Cooling for Subaru Forester

This CSF radiator is built for 2003-2005 Subaru Forester applications with an OE-style plastic tank and aluminum core design. CSF Part Number 3139 is engineered for direct-fit cooling performance in a down-flow layout, making it a practical replacement for a worn or leaking factory radiator.

The CSF 3139 radiator uses a 1-row core with a 5/8-inch thickness, 27 1/16-inch core width, and 14 3/16-inch core length. It features a right-side 1 9/16-inch inlet and left-side 1 9/16-inch outlet, plus a high-efficiency concentric transmission oil cooler measuring 14 3/4 inches. This radiator is designed for Subaru Forester owners who need a replacement that matches the original tank-and-core construction.

Key Features

• Fits 2003-2005 Subaru Forester, N/A
• CSF Part Number 3139
• 1-row down-flow radiator design
• Plastic tank and aluminum core construction
• Right inlet and left outlet configuration
• Integrated high-efficiency concentric oil cooler
• OE-style replacement layout for factory-style fitment

Product Details

CSF manufactures radiators to high-performance standards and validates cooling performance through laboratory wind-tunnel testing. The brand supplies a wide range of radiator applications across many vehicle platforms, and this CSF 3139 unit reflects that OE-style engineering approach. For Subaru Forester cooling system service, this radiator provides the correct core style, hose orientation, and cooler integration for the listed model years.

This part cross-references Hayden 2674 and Spectra Premium CU2674 for the same application.

Common Problems This Radiator Can Address

• Coolant leaks from cracked or aged radiator tanks
• Restricted cooling from a deteriorated core
• Overheating caused by reduced heat transfer
• Transmission fluid temperature concerns tied to a failing internal cooler
• Fitment issues from non-OE-style replacement radiators

Installation Notes and Tips

Verify inlet and outlet orientation before installation: this radiator uses a right-side inlet and left-side outlet. Confirm the vehicle uses the listed OE-style plastic tank and aluminum core configuration, and transfer any required sensors or fittings from the original radiator if applicable to your vehicle setup. Inspect hoses, clamps, and coolant condition during replacement to help prevent repeat cooling-system issues.

Quality Assurance

CSF states that its radiators are manufactured in ISO/TSO-certified facilities and tested for cooling performance validation. The brand has supplied radiators worldwide for decades, with extensive model coverage across many vehicle applications.