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Designer: Mishimoto


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  • Direct fit for the 1999–2006 BMW E46 non-M Models
  • All-aluminum TIG-welded construction for maximum durability during repeated cold and hot transitions
  • Integrated coolant level mechanism retains the use of your stock coolant level sensor
  • Compatible with all stock quick-disconnect fittings
  • Compatible with both manual and automatic transmissions
  • Included high-pressure 2.0 bar radiator cap raises the boiling point of engine coolant to provide a safer and more efficient system
  • Fits with stock and Mishimoto E46 Aluminum Radiator
  • Fits with stock and Mishimoto E46 Performance Fan Shroud Kit
  • Mishimoto Lifetime Warranty


Add some additional reliability and engine bay styling with the Mishimoto BMW E46 Aluminum Coolant Expansion Tank. The stock E46 expansion tank is prone to failure after years of constant temperature variations. The Mishimoto E46 expansion tank is constructed from durable, TIG-welded aluminum for optimal durability and longevity. The engineers at Mishimoto have designed an aluminum expansion tank that is fully compatible with your stock coolant level sensor! How does it work? Well the stock E46 expansion tank has a floating magnet that activates your low coolant light when the contacts are closed. Engineers replicated this feature with a CNC billet slide and floating magnet that is made to the same specifications as stock. The E46 expansion tank features CNC fittings that are fully compatible with all of the quick-disconnect fittings on your vehicle! It features a polished finish that will look great in your engine bay. This E46 expansion tank is a direct fit for the stock and Mishimoto BMW E46 Performance Fan Shroud Kit! As with all our BMW performance parts, this expansion tank includes the Mishimoto Lifetime Warranty.


Mishimoto Automotive (“Mishimoto”) warrants its products under this lifetime limited warranty policy (“Warranty Policy”). This Warranty Policy applies solely to: (i) Mishimoto Products purchased directly from Mishimoto or Mishimoto authorized dealers (each a “Mishimoto Product” and collectively, the “Mishimoto Products”) and (ii) the original purchaser of such Mishimoto Product (“Purchaser”). This Warranty Policy is non-transferable and all claims under this Warranty Policy must be accompanied by the original sales receipt. The terms and conditions of this Warranty Policy are subject to change by Mishimoto at any time without notice.

For our complete warranty policy, please click here.



  • Purchase Includes(1) Aluminum Expansion Tank
  • (1) 2.0 Bar Mishimoto Radiator Cap
  • (1) Overflow Hose
  • (1) Worm Gear Clamp
  • Mishimoto Lifetime Warranty
  • Fits1999–2000 BMW 328i (E46, all bodies)
  • 1999–2000 BMW 323i (E46, all bodies)
  • 2001–2005 BMW 325i (E46, all bodies)
  • 2001–2006 BMW 330i (Including ZHP Models)
  • Engine CodesM52
  • M54
  • M56
  • Chassis CodesE46
  • Material6061 Aluminum
  • NoteAfter a few hot and cold cycles, Mishimoto recommends checking the expansion tank for leaks, as well as proper fastening of the quick disconnect fittings. This expansion tank has an integrated floating level and should not activate any low coolant lights if properly filled to the correct levels.
  • This expansion tank features CNC machines quick disconnect fittings, please ensure that the fittings are properly attached before operating the vehicle.
  • ColorSL
  • BaffledNo

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