WCE S63 TU4 Billet Coolant Reservoir Expansion Tank - F90 M5 / F92 M8

WCE S63TU4 Billet Coolant Reservoir Expansion Tank — F90 M5 / F92 M8

The OEM plastic expansion tank on the S63TU4 is a known failure point. It cracks, and when it does it dumps coolant straight down onto the injectors and coils — which turns a cheap part into an expensive weekend. Swapping in another factory plastic unit just resets the clock on the same failure. This one doesn't fail.

Machined from 6061 billet aluminum, the WCE reservoir is a permanent fix rather than a replacement interval. Every factory interface is retained — quick-connect fittings, OEM pressure cap, and the stock coolant level sensor — so the car sees exactly what it expects. No warning lights, no phantom level readings, no adapters or splicing. The O-ring housing is machined to accept the OEM O-ring off your stock reservoir, and internal baffling keeps fluid movement in check under hard driving and track use.

Highlights

• 6061 billet aluminum, CNC machined in-house
• Permanently eliminates OEM plastic reservoir cracking and coolant leaks
• All OEM quick-connect fittings retained — no modification to hoses or lines
• OEM pressure cap retained, factory pressure relief preserved
• OEM coolant level sensor retained for accurate readings and no dash lights
• O-ring housing machined for the factory O-ring off the stock unit
  
• Plug and play — no cutting, drilling, or tuning required

Specifications

Installation Notes

Transfer the OEM coolant level sensor probe and the factory coolant cap from your original reservoir — both are reused on this unit. The cap does not need to line up with the arrows; tighten until snug. The sensor probe occasionally binds on removal; trimming around its base is sometimes necessary to pull it cleanly. Reservoir only — sensor and cap are not included. Sensor and O-Ring reused from stock unit.