CSF #8355 High-Performance Aux Radiator - BMW F2X M240i, F3X 340i/440i, F87 M2

Gen 1 B58 cars are known to run coolant temperatures up into limp mode when pushed, and the small factory auxiliary radiators are part of the reason. CSF's #8355 replaces the plastic-tank OEM unit with an all-aluminum radiator that has a much thicker core. It goes into the factory location and is meant to hold off heat soak longer on the street or at the track.

What you get

• Thicker 2-row core. 42 mm thick versus 27.5 mm and a single row on the factory part, using CSF's B-Tube core with multi-louvered 5 mm fins.
• TIG-welded aluminum tanks with more volume than the stock plastic tanks, which are crimped on with a gasket.
• Built-in mounting frame in aluminum, so no separate cradle is needed and it is stronger than the factory plastic pod.
• OEM-style quick-connect inlet and outlet, a removable rock guard and a satin black finish.
• Pressure and leak tested one by one, with a 2-year limited warranty from CSF.

Good to know

• Sold as one radiator, and it fits either side. Most cars use two.
• Some 340i, 440i and M240i trims left the factory without aux radiators. Check your VIN, and cars without them may need brackets and a little trimming of the air ducting.
• Professional installation is required.

Brand: CSF · Part #: 8355

• Ships from the brand or distributor, usually in 3–7 business days.
• Shipping is charged at the carrier's rate, shown at checkout. Orders over 70 lb ship by freight for a flat $99.
• Unused parts can be returned within 30 days. Some items are marked no-refund in their description.

Full details are on our shipping and returns page.