BMW Full Metal Aluminum Expansion Tank Upgrade – Reinforced Cooling System Reliability, Race-Inspired Design - Replaces OE Part No. 17111707505

Upgrade one of the most failure-prone parts of your BMW’s cooling system with a much stronger, more durable solution built for long-term reliability. This Full Metal Aluminum Expansion Tank is designed to replace the weak factory plastic unit with a reinforced all-metal design that is better suited for heat, pressure, and repeated thermal cycling.

Factory plastic expansion tanks are well known for becoming brittle over time. After years of engine heat and pressure changes, the original plastic can crack, warp, or fail without much warning, leading to coolant leaks, overheating, and unnecessary downtime. That risk becomes even more frustrating on older BMWs where certain cooling system parts are becoming harder to find in good quality.

This upgraded aluminum expansion tank solves that problem by replacing the vulnerable plastic housing with a full metal construction that is far better equipped to handle demanding engine bay conditions. The result is a stronger, more confidence-inspiring cooling system component that not only looks more premium under the hood, but also helps reduce one of the common failure points found on aging BMW platforms.

For enthusiasts restoring older chassis, maintaining a hard-to-find model, or simply looking to future-proof their cooling system, this is the type of upgrade that makes sense. Instead of installing another plastic replacement that may eventually suffer the same fate, this aluminum tank offers a more permanent, performance-inspired solution built around durability and peace of mind.

Key Features:

• Full Metal Aluminum Construction: Replaces the failure-prone factory plastic design with a far stronger aluminum housing built for long-term durability.
• Improved Cooling System Reliability: Helps reduce the risk of cracks, leaks, and fatigue commonly associated with aging plastic expansion tanks.
• Better Resistance to Heat and Pressure: Built to withstand demanding engine bay temperatures and repeated thermal cycles more effectively than OEM-style plastic tanks.
• Ideal for Older and Hard-to-Find Applications: A smart upgrade for BMWs where replacement cooling parts may be harder to source or where long-term dependability matters most.
• Race-Inspired Under-Hood Design: Adds a cleaner, more serious performance look to the engine bay while serving a real functional purpose.
• Direct Replacement Design: Engineered to replace the factory expansion tank while improving strength and overall confidence in the cooling system.

FITMENT: BMW 3 Series – E30 (1984–1987) including

• 325e Coupe (1985–1987) – 2.7L M20 SOHC
• 325e Sedan (1984–1987) – 2.7L M20 SOHC
• 325 Coupe (1986–1987) – 2.7L M20 SOHC
• 325 Sedan (1986–1987) – 2.7L M20 SOHC
• 325es Coupe (1986–1987) – 2.7L M20 SOHC
• 325i Sedan (1987) – 2.5L M20 SOHC
• 325i Convertible (1987) – 2.5L M20 SOHC
• 325is Coupe (1987) – 2.5L M20 SOHC

FITMENT: BMW 5 Series – E28 (1982–1988) including

• 528e Sedan (1982–1988) – 2.7L M20 SOHC

Compatible with both RWD variants and equivalent factory applications using OE part number 17111707505.

REPLACES OE PART NUMBER: 17111707505

If you’re unsure whether this aluminum expansion tank fits your specific BMW, please contact us with your VIN and we’ll be happy to verify compatibility before you order.

Please refer to the “Fitment” section in the product description for compatibility details.