Aluminum Coolant Expansion Tank for BMW E30 (1988-1991) 325i is iX (E30/M20)

Stop gambling with 30-year-old plastic. Replace that yellowing, brittle expansion tank before a hairline crack cooks your M20 head gasket.

Aluminum Coolant Expansion Tank for BMW 325i/is/iX (E30/M20)

If you drive an E30, you know the anxiety of watching the temperature needle creep past the 12 o'clock mark. The M20 inline-six is a legendary engine, but the factory cooling system is its Achilles' heel. Specifically, the stock plastic expansion tank sits right near the exhaust headers on LHD cars, baking in heat for decades until it turns opaque and brittle.

This aluminum upgrade solves the weak link in your cooling loop. Whether you have a 1988 sedan or a late-run 1993 Cabriolet, this tank is designed specifically for the M20B25 engine layout. It fits the specific mounting points of the late-model cooling system update used on the 325i, 325is, and 325iX. By switching to aluminum, you eliminate the risk of the plastic seam splitting during a spirited drive or a track day.

Why You Need This Upgrade

• Bulletproof Reliability: Replaces fragile, heat-cycled plastic with TIG-welded aluminum that won't crack under pressure.
• Engine Bay Aesthetics: Ditch the ugly, yellowed stock container for a clean, metallic finish that pops next to your intake manifold.
• M20 Insurance: Prevents catastrophic coolant loss that leads to the dreaded warped cylinder head common on overheated M20s.
• Direct Fitment: Mimics the factory orientation for hoses and the level sensor, ensuring a straightforward swap without custom fabrication.

Technical Specifications

Installation & Fitment Notes

This unit is a direct replacement for the late-model cooling system setup found on 1988+ cars. Please verify your vehicle has the expansion tank located on the driver's side (LHD) fender area, distinct from the radiator. Note for 1992-1993 Convertible Owners: This fits your E30 chassis M20 engine specifically; it does not fit E36 M50 models.

Protect your classic 3-Series and drive with confidence—upgrade your cooling system today.