ECS Tuning BMW E46 M3 (S54 3.2) Coolant Degas/Return Hose – Pre‑Formed Silicone Breather with CNC Aluminium Coupler – OEM‑Style Direct Fit Expansion Tank Vent / Header Tank Return / Radiator Bleed & Overflow Line

E46 M3 S54 Degas Return Hose Upgrade by ECS Tuning

Protect your BMW’s cooling system by replacing the fragile plastic breather line with this ECS Tuning moulded silicone return hose and CNC‑machined aluminium coupling. Age and engine bay heat make the factory breather hard and brittle, which can lead to seepage, coolant loss and temperature spikes. This drop‑in swap keeps the tidy, factory‑look routing while delivering long‑term durability and dependable performance on the road and on track.

Built for reliability

• Designed specifically for BMW E46 M3 with the S54 3.2‑litre straight‑six
• Moulded silicone hose maintains OE routing and a stock appearance
• Fluorosilicone inner liner is coolant safe and highly heat resistant
• CNC‑machined 6061‑T6 aluminium union, black anodised to MIL‑A‑8625F Type II Class 2 for strength and corrosion protection
• One‑piece alloy connector minimises potential leak points
• Pressure validated at twice normal system pressure for confidence under hard use
• Interfaces with original clips and brackets for a neat install

Note: due to small variations in silicone wall thickness, the expansion tank clip may not positively latch on some vehicles.

What is included

• Black reinforced silicone hose with fluorosilicone liner
• Black anodised alloy coupling that mates cleanly to the upper radiator hose fitting

Why owners choose this upgrade

It is a smart preventative maintenance part that eliminates a known weak link in the S54 cooling circuit. Expect excellent heat tolerance, a clean OE‑style finish and a simple swap that can typically be completed without draining the system. We have installed this on customer cars and feedback has been consistently positive for fit, finish and leak‑free operation.

Fitment

BMW M3 E46 with S54 3.2 petrol inline‑six.

Installation and support

Straightforward DIY for enthusiasts. Prefer professional fitting? Book with MJ Modifications in Warwickshire. Request a quote at info@mjmodifications.co.uk.

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