Thermostat to Cylinder Head Hose Replacement

  • Materials Required

    Tools Required:

    • 8MM Wrench
    • Flathead Screwdriver
    • Pick Tool

  • Start w/ Cold Engine

    Ensure you conduct this DIY on a vehicle with a cold engine.

  • Remove Hose Front Screw

    Remove the front screw from the cylinder head hose using a 10MM open-ended wrench.

  • Switch Tools

    Switch to a 10MM socket and ratchet as an open-ended wrench will not fit in the tight space.

  • Remove Hose Rear Screw

    Remove the rear screw from the cylinder head hose using a 10MM socket and ratchet.

  • NOTE*

    It is recommended to replace the two 10MM hex screws.

    OE Part No. 07119905591

  • Detach the Hose

    Detach the old factory hose from your vehicle's cylinder head.


    It's extremely important to check the hose port on the cylinder head for any debris. The old hose almost always breaks off small plastic pieces that could possibly fall into the engine. Trace your finger in a circular motion and check there are no plastic pieces broken off.

  • Disconnect Expansion Tank Return Hose

    Disconnect the expansion tank return hose by prying up on the metal retention clip and simply pulling it off of the nipple.

  • Remove Expansion Tank Screws

    Remove the two 10MM expansion tank retention screws.

  • Move Expansion Tank

    Move the expansion tank all the way forward, to give yourself access to the vehicle's thermostat.

  • Loosen Thermostat Hose Band Clamp

    Loosen the band clamp holding the hose to the thermostat (white arrow) with a flathead screwdriver. Once loosened, pull the hose from the thermostat.

  • Remove The Old Hose

    Carefully wiggle the old hose out from your engine bay.

  • Transfer Hose Band Clamp

    Transfer the band clamp from the old hose to the new one. Install the band clamp so the screw faces upward, so you can easily reinstall it and remove it in the future.

    (Hose Part No. 11437545890)

  • Install New Hose to Thermostat

    Install the hose to the thermostat and tighten the band clamp screw until it's snug into place and can not be pulled off.

  • Attach Hose to Cylinder Head

    Firmly attach the new hose to your vehicle's cylinder head and hand tighten the retention screws into place.

  • Tighten the Retention Screws

    Tighten the cylinder-head hose retention screws into place with a 10MM wrench and/or socket.

  • Place Expansion Tank Into Place

    Place the expansion tank back into place ensuring the drain port at the bottom fully aligned to the frame of the vehicle.

  • Tighten Expansion Tank Screws

    Install and hand-torque the expansion tank screws with a 10MM socket and ratchet.

  • Re-install Expansion Tank Return Hose

    Re-install expansion tank return hose to the expansion tank nipple and press retention clip down into place.

  • Fill and Bleed Cooling System

    Fill your cooling system with approved BMW coolant until full, then carry out cooling system bleed procedure.

    BMW Cooling System Bleed Procedure 
  • DIY Complete!

    Good job replacing your thermostat to cylinder head hose! Be sure to keep an eye out for coolant leaks or any signs of overheating.