BMW Coolant Expansion Tank Replacement | 2004-2010 5 Series (E60), 6 Series (E63)

bmw coolant reservoir replacement

BMW Coolant Expansion Tank Replacement – 1 Hour

BMW expansion tank replacement BMW expansion tank replacement

The BMW Repair Guide used this 2005 645ci for the following article. To see other repairs on our site using this actual car, please click on the image below!

A BMW coolant expansion tank replacement on your N62 V8 engine is an easy repair that can insure you from being stranded on the side of the highway or dealing with a blown cylinder head gasket.

If there is an “Achilles Heel” on older (10 years plus) BMWs, it’s failure of the coolant system…most notably the coolant expansion tank. The coolant expansion tank is a molded plastic part that is under constant heat and pressure. After years of this abuse, the plastic expansion tank can become brittle and fail. When a coolant expansion tank fails you will know it; it is usually a loud bang followed with steam and fluid being ejected from the hood of the car. Not a pretty sight.

The coolant expansion tank is a molded plastic part that is under constant heat and pressure.

If you are on the road and this happens, pull over immediately and shut the vehicle down. Even driving for a short time with a failed coolant tank will result in a blown cylinder head gasket, and the demise of your vehicle (unless you need a parts car parked in your backyard).

Many owners do not wait for failure to perform a BMW coolant expansion tank replacement. In fact, them BMW Repair Guide recommends a BMW coolant expansion tank should be replaced every ten years/100,000 miles for regularly driven vehicles.

Parts, Tools and Supplies

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Part Quantity Part # Description
Coolant expansion tank 42986 1 17137542986 OEM Rein
Coolant expansion tank cap 39021 1 17117639021 Genuine BMW
Coolant/Anti-freeze 67704 1-2 82141467704 100% strength, mix 50/50 with distilled water


Tools and Supplies
Metal pick
Drain pan – 5 gallon

  1. Make sure engine has completely cooled before starting this repair.
  2. Identify the location of the BMW coolant expansion tank in your coolant reservoir replacement
  3. Position a 5 gallon drain pan under coolant expansion tank to catch any spilled coolant reservoir replacement
  4. Remove the vent hose by using a metal pick to release the metal clip and pulling free from the expansion tank. If hose will not pull off, use a flat blade screwdriver and the palm of your hand and gently push coolant reservoir replacementbmw coolant reservoir replacementbmw coolant reservoir replacement
  5. Remove the overflow hose using the same technique as in step 4.
  6. Use a T20 torx bit to remove the two BMW coolant expansion tank mounting coolant reservoir replacement
  7. Pull the coolant expansion tank out of engine compartment until you can access the bottom reservoir coolant reservoir replacement
  8. Remove the reservoir hose using the same technique as in steps 4 and 5 coolant reservoir replacement
  9. Remove the fluid level sensor electrical connection on bottom of expansion coolant reservoir replacement
  10. Remove the BMW coolant expansion tank from the vehicle.
  11. Install new coolant expansion tank using the reverse steps above.
  12. Fill reservoir with fresh coolant, replace cap, and start engine. Allow coolant to circulate through engine for a couple of minutes. Turn off engine, remove cap, and top off coolant if necessary. Only use Genuine BMW coolant/antifreeze mixed 50/50 with distilled water.

BMW Coolant Expansion Tank Replacement Finished
If you have any questions or comments, please feel free to contact us. And congratulations for Doing It Yourself!

The Repair Difficulty Level displays graphically how challenging the repair is, from easy to advanced. Easy repairs usually require very few tools, have short repair times and do not require jacking and supporting the vehicle. As the difficulty level rises, expect the repair to demand more time, specialized tools, and better understanding of mechanics to complete the job.

Make Model Submodel Engine
BMW E60 525i M54 2.5L
BMW E60 525i N52 3.0L
BMW E60 525xi N52 3.0L
BMW E60 528i N52 3.0L
BMW E60 528xi N52 3.0L
BMW E60 530i M54 3.0L
BMW E60 530i N52 3.0L
BMW E60 530xi N52 3.0L
BMW E60 535i N54 3.0L
BMW E60 535i N55 3.0L
BMW E60 535xi N54 3.0L
BMW E60 545i N62 4.4L
BMW E60 550i N62 4.8L
BMW E60 M5 S85 5.0L
BMW E61 525i M54 2.5L
BMW E61 530xi N52 3.0L
BMW E61 535xi N54 3.0L
BMW E63 645Ci N62 4.4L
BMW E63 650i N62 4.8L
BMW E63 M6 S85 5.0L
BMW E64 645Ci N62 4.4L
BMW E64 650i N62 4.8L
BMW E64 M6 S85 5.0