Performance Radiator for Buick Rainier (2004-2007) 5.3L

Direct-Fit All-Aluminum Performance Radiator for 2004-2007 Buick Rainier 5.3L

What it Does: Replaces failure-prone OEM composite radiators with a fully welded AA5052 aluminum cooling assembly to maintain optimal engine and transmission operating temperatures under load.

The Stock Rainier Thermal Breakdown

The factory cooling system on the GMT360 platform relies on plastic end tanks crimped onto an aluminum core. Over repeated thermal cycles, the factory plastic degrades, embrittles, and develops stress fractures along the tank seams and inlet neck. Under heavy towing or extended uphill grades, these composite tanks cannot withstand sustained hydraulic pressure fluctuations, risking catastrophic coolant loss and severe cylinder head warping on the 5.3L V8.

The Engineering Solution

Engineered for maximum thermal dissipation, this performance downflow radiator features 100% TIG-welded AA5052 aircraft-grade aluminum end tanks mated to a high-efficiency aluminum racing core measuring 18.11 in x 26.69 in x 1.02 in. The brazed tube-and-fin design maximizes thermal transfer surface area while eliminating vulnerable plastic seams and rubber gaskets. An integrated internal transmission oil cooler protects the 4L60E/4L70E gearbox from thermal breakdown, ensuring consistent line pressures and longevity.

Technical Specifications

Compatibility

• 2004 Buick Rainier CXL / CXL Plus 5.3L V8 (LM4)
• 2005 Buick Rainier CXL 5.3L V8 (LH6)
• 2006 Buick Rainier CXL 5.3L V8 (LH6)
• 2007 Buick Rainier CXL 5.3L V8 (LH6)
• Note: Fits 5.3L V8 models only; does not fit 4.2L Inline-6 variants.

The Buick Heavy-Duty Caliber

Built to handle heavy towing and extreme heat loads, this all-aluminum unit provides the rugged dependability required for high-stress SUV and truck applications.