TECH TIP: MINI Cooper Cooling & Heating

Problem: MINI Cooper S - Coolant Expansion Tank Failure

OEM Part Numbers:
17 13 7 529 273

Vehicles Effected:

  • Mini Cooper "S" R53 (2002 to 2006)


Replace the take with an Original plastic tank (17 13 7 529 273)
Or select Aluminum replacement tanks:
Polished Aluminum Coolant Tank Upgrade - Part# 300372
Anodized Black Coolant Tank Upgrade - Part# 300373

(see tank selection at the bottom of page)

On the Mini Cooper "S" 2002 to 2006 R53:

The coolant expansion tank is a very common failure. The engine coolant system is under pressure during operation. Pay close attention to leaks around the coolant reservoir, item number 17 13 7 529 273. If there are any defects in the coolant reservoir it is recommended to replace the tank before a catastrophic failure occurs, which may lead to coolant loss and costly engine damage. A visual inspection to the engines cooling system is easy to do, If you know what to look for! (follow the steps below)

Coolant Expansion Tank & Cap Product Information


To inspect the system for leaks:

  1. With a cool engine remove the cap and top off the cooling system with plain tap water.
  2. Prior to reinstalling the cap make sure the screw threads on the cap and tank are in good condition.
  3. Make sure the seal in the cap is in place and not damaged
  4. With cap installed start the engine and allow to idle until engine reaches operating temperature.
  5. Once at temperature the pressure in the system will force water out of any visible cracks.
  6. See the highlighted inspection points below for possible leaks.


View Larger Image

1. The coolant reservoir tank must be removed from the vehicle to ensure proper inspection for damage.


View Larger Image

2. Inspect the seams around the middle of the unit for coolant stains and leaks that develop while the unit is under pressure during operation.


View Larger Image

3. Coolant build-up and white deposits form at the corners and sides, and coolant leaks begin to run down the side of the tank. Also, cracks in the plastic are common around the corners & filler neck.


View Larger Image

4. The coolant leak is mostly visible from the bottom side and may go unnoticed in the driveway. This is often due to the fact that the system is under operating pressure while driving. Once the vehicle is turned off or left sitting overnight the vehicle is slowly bleeding pressure off and may not present with a leak until there is a catastrophic leak. This is why a visual inspection is critical. Watching for a "low coolant" warning light or finding that you have to add coolant from time to time is an indicator that something is definitely wrong.


View Larger Image

5. You may already see the tank has turned a darker color as the plastic begins to deteriorate, but appears to have no leaks from the top view.


MINI Cooper "S" Coolant Tanks we Offer:


A brand new OE Replacement Tank with Cap is easily installed in minutes and could save the life of your Mini Cooper's engine, or add to the years of operation.

View Coolant Tank

Polished Aluminum

Or, choose a brand new Polished Aluminum Coolant Tank as an upgrade coolant tank replacement.

View Coolant Tank

Black Anodized

Or, choose a brand new Aluminum Coolant Tank (Anodized Black) as an upgrade coolant tank replacement.

View Coolant Tank

Get Pro Shop Tools for your BMW from PROMINI! - click here

MINI Cooper S Service Manual