How to Replace Coolant Pipe and Thermostat, 2nd gen MINI, N12 N14 N18


OK, SO YOU’VE DIAGNOSED A LEAKING COOLANT PIPE (YAY!), NOW WHAT?
Leaking coolant pipe N12 N14 N18 MINI

How To Replace Mini Coolant pipe

How to replace MINI coolant pipe – Replacing the Mini Coolant pipe (and the associated o-ring) requires removal of the thermostat.  Therefore, we recommend that the coolant pipe and o-ring as well as the the thermostat, always be replaced in tandem unless one or the other has recently been replaced.

The following DIY steps are specifically for the N14 engine (turbocharged) which is used in the 2007 through 2010 “S” models and the 2011 through 2013 JCW models.  However, the majority of the steps are the same for all N12 (non-turbo), N14 and N118 engines used in the R55, R56, R57, R58, R59, R60 and R61 MINI models.

Follow along as we learn how to replace Mini Coolant pipe and the thermostat (due to a leaking coolant pipe) on a 2009 R55 Clubman S JCW.  Click HERE to order the replacement parts for your MINI, from eEuroparts.com.

Note that if you have an “S” model, it is also very advantageous to perform a walnut blast (de-carboning) on the intake ports/valves while the engine is apart for the coolant tube replacement.  Conversely, if a walnut blast is being performed, preemptively replacing the coolant tube (and thermostat) while the intake manifold is removed, is a smart move.  If the tube has not been replaced …. it is going to fail at some point.

PARTS NEEDED:

How to replace MINI coolant pipe – PROCEDURE:

  1. Preparation

    1. We recommend that the engine be cold or cooled off as we will be working closely around the engine and coolant.
    2. Have fresh coolant and distilled water at hand, for reassembly.
    3. Have a drain pan (for coolant) handy.  Larger is better as the bulk of the coolant will drain on top of the transmission and down around the front and rear.
    4. A floor jack may be required to lift the front of the vehicle in order to slide the drain pan under the car.
  2. Remove the engine air filter housing cover and MAF.

    1. Unplug the MAF harness plug.
    2. Loosen the intake pipe hose clamp.
      MINI coolant tube replace how to
    3. Loosen the filter cover securing screws (the screws stay captive in the cover).
      MINI coolant tube replace how to
    4. Pull up the cover and pull the MAF from the MAF to turbo pipe.
      MINI coolant tube replace how to
  3. Remove the filter and lower filter housing.

    1. Remove the two housing securing screws.
      MINI coolant tube replace how to
    2. Gently pry the housing upward from the rubber securing grommets, pull the intake elbow from the intake pipe and remove the housing.
      MINI coolant tube replace how to
  4. Remove the Positive Crankcase Ventilation (PCV) hose.

    1. Pry up and remove the hose securing clip at the valve cover.
      MINI coolant tube replace how to
      MINI coolant tube replace how to
    2. Pull the end of the hose from the valve cover nipple.
      MINI coolant tube replace how to
    3. Unclip the PCV heater harness plug and remove from the heater plug housing.
      MINI coolant tube replace how to
      MINI coolant tube replace how to
  5. Remove the intake pipe.

    1. Loosen the intake pipe to turbo hose clamp.
      MINI coolant tube replace how to
    2. Pull the intake pipe from the turbo inlet nipple and remove the pipe.
      MINI coolant tube replace how to
      MINI coolant tube replace how to
  6. Disconnect the Vacuum pipe.

  7. Pinch the unlock tabs and pull the pipe connector from the nipple on the vacuum pump.

    MINI coolant tube replace how to
    MINI coolant tube replace how to

    NOTE: Steps 8 through 14 detail removal of the intake manifold.  Note that, while this job can technically be done without removal of the intake manifold, the coolant pipe is fully hidden and rather difficult to access, remove and accurately replace, without removing the manifold.

  8. Disconnect the intake manifold PCV hose.

    1. Pinch the locking ring and pull the hose connector from the valve cover nipple.
      MINI coolant tube replace how to
      MINI coolant tube replace how to
      MINI coolant tube replace how to
  9. Disconnect the Manifold Absolute Pressure (MAP) sensor harness plug.

    1. Pry the locking tab up and pull the harness plug from the MAP sensor.
      MINI coolant tube replace how to
      MINI coolant tube replace how to
  10. Remove the charge pipe intake elbow hose.

    1. Loosen the hose clamp on the upper end of the hose.
      MINI coolant tube replace how to
    2. Pry the securing clip on the lower end of the hose.  The clip does not need to be fully removed.
      MINI coolant tube replace how to
    3. Pull the lower end of the hose up from the connector  and pull the upper end of the hose off of the plastic intake charge pipe.
      MINI coolant tube replace how to
      MINI coolant tube replace how to
  11. Remove the “sound generator” assembly.

    1. Remove the securing screw.
      MINI coolant tube replace how to
    2. Pull the connector end from the firewall connector.
      MINI coolant tube replace how to
    3. Loosen the hose clap securing the sound generator tube to the intake tube.
      MINI coolant tube replace how to
    4. Pull the hose from the nipple on the intake tube and lift the assembly out.
      MINI coolant tube replace how to
  12. Remove the lower intake charge tube from the throttle body.

    1. Loosen the hose clamp that secures the tube to the throttle body.
      MINI coolant tube replace how to
    2. Gently twist and pull the tube from the throttle body and pull the tube up and out.
      MINI coolant tube replace how to
  13. Remove the intake manifold.

    1. Remove the intake manifold support screw.  This screw is under the manifold and is difficult to access.  You can see the screw using a mirror and a light.  It is above and to the inside of the throttle body.  You can just feel the screw if you reach over the intake manifold and around the rear and under.  Use a 1/4″ drive ratchet, extensions and 10mm socket.
      MINI coolant tube replace how to
      MINI coolant tube replace how to
      MINI coolant tube replace how to
    2. Disconnect the vacuum tube elbow from the fuel tank breather valve (driver side) by pinching the locking tabs on the elbow housing and pull the elbow from the valve nipple.
      MINI coolant tube replace how to
      MINI coolant tube replace how to
    3. Remove the 5 intake manifold securing nuts.
      MINI coolant tube replace how to
    4. Pull the manifold slightly away from the cylinder head, but do not attempt to fully remove it yet.
    5. Pry the harness securing clip from the tab on the intake manifold (passenger side).
      MINI coolant tube replace how to
    6. Pry the harness securing rivet from the intake manifold.
      MINI coolant tube replace how to
    7. Pull the manifold off of the studs and away from the cylinder head (do not attempt to fully remove yet).
      MINI coolant tube replace how to
    8. Pry the harness securing rivet from the throttle body hosing, just above the throttle body harness plug.
      MINI coolant tube replace how to
      MINI coolant tube replace how to
    9. Unclip and remove the throttle body harness plug.
      MINI coolant tube replace how to
      MINI coolant tube replace how to
    10. Pull the pressure converter valve rubber hanger from the flat metal mounting tab.
      MINI coolant tube replace how to
    11. Pry up the locking tab and remove the fuel tank breather valve harness plug.
      MINI coolant tube replace how to
    12. You should now be able to lift and remove the intake manifold.  Carefully watch for any stray harness clips that may need to be disconnected.
  14. Pry up the locking tab and disconnect the intake camshaft position sensor harness plug.

    MINI coolant tube replace how to

  15. Pry the harness securing clip from the tab on the valve cover.

    MINI coolant tube replace how to

  16. Disconnect the vacuum hose from the vacuum pump and the turbo wastegate vacuum valve.

    MINI coolant tube replace how to
    MINI coolant tube replace how to
    MINI coolant tube replace how to

  17. Pry the locking tab and disconnect the thermostat temp sensor harness plug.

    MINI coolant tube replace how to

  18. Disconnect the oil pressure sensor harness plug.

    MINI coolant tube replace how to

  19. Remove the DME (Digital Motor Electronics …. the engine management control unit) harness cover.

    1. Remove the securing screw.
      MINI coolant tube replace how to
    2. Unclip the securing tabs and remove the plastic cover.
      MINI coolant tube replace how to
  20. Disconnect the two rearward DME harness plugs.

    1. Lift the locking levers and pull the harness plugs up and out of the DME connector housings.
      MINI coolant tube replace how to
  21. Disconnect the harness plug just forward of the DME.

    MINI coolant tube replace how to
    MINI coolant tube replace how to

  22. Slide the plastic engine harness housing upward from the cylinder head until it is free from the mounting bracket. pull all of the harnessing over toward the passenger side.

    MINI coolant tube replace how to
    MINI coolant tube replace how to

  23. Optional step (this gives more working room) – Disconnect ignition coil harness assembly.

    1.  Unclip and remove the coil harness cover.
    2. Disconnect the ignition coil harness plugs and ground connectors.
    3. This now gives more room to pull the engine harness over to the passenger side, for additional clearance.
  24. Disconnect the upper and lower radiator coolant hoses.

    1. Pinch the hose clamp on the upper radiator hose and pull it back over the hose (off the thermostat nipple).
      MINI coolant tube replace how to
    2. Pull the hose off the thermostat nipple.
    3. Repeat for the lower radiator hose.
      MINI coolant tube replace how to
  25. Disconnect and remove the thermostat to coolant reservoir and turbocharger coolant hose.

    1. Loosen and remove the coolant pipe banjo bolt at the turbocharger.
      MINI coolant tube replace how to
    2. Remove the hose Assembly mounting bracket bolt.
      MINI coolant tube replace how to
    3. Pinch and pull back the hose clamp at the thermostat nipple.
    4. Pull the hose from the thermostat nipple and from around the turbocharger housing.
      MINI coolant tube replace how to
  26. Remove the remaining two coolant hoses for the heater, at the rearward side of the thermostat, by pinching that clamps, sliding them back over the hoses and removing the hoses from the thermostat nipples.

  27. Note the plastic coolant pipe in the area under where the intake manifold was mounted.  Pull the thermostat to coolant pipe securing clip away from the pipe, using a small screwdriver or pick tool.  You must reuse this clip with the new pipe …. don’t lose it.

    MINI coolant tube replace how to
    MINI coolant tube replace how to

  28. Remove the thermostat.

    1. Remove the three bolts securing the thermostat to the cylinder head.
      MINI coolant tube replace how to
    2. Carefully pull the thermostat away from the cylinder head while pulling the connection elbow from the coolant pipe.
      MINI coolant tube replace how to
  29. Remove the coolant pipe securing bolt at the tab on the middle area of the pipe.

  30. Carefully pull the coolant pipe from the mounting hole in the passenger side of the engine block (water pump mounting boss).

    MINI coolant tube replace how to

  31. If the coolant pipe has been leaking, you will likely find that the o-ring and some broken plastic bits are still lodged into the mounting hole.  Carefully remove these pieces and the o-ring.

    MINI coolant tube replace how to
    MINI coolant tube replace how to

Assembly notes:

Reassembly is opposite of removal.
Oh come on … it’s a joke……

Really, though, the assembly is pretty much just reversing the steps that got you to this point, following the how to replace MINI coolant pipe DIY.  However, see the notes detailed below, as you reassemble. You may wish to take this opportunity to replace any (or all) of the Coolant hoses that may show deterioration or have known long life on them.  You will also need new Intake manifold gaskets.

.

  1. Lubricate the o-ring, on the end of the Mini Coolant pipe, with silicone grease before inserting into the waterpump mounting boss hole.

    MINI coolant tube replace how to

  2. Clean up the thermostat gasket mounting area on the cylinder head.

    MINI coolant tube replace how to

  3. Lubricate the o-ring on the thermostat nipple (a new thermostat is recommended) before inserting into the coolant tube.

  4. Clean up the intake manifold gasket mounting areas on the intake side of the cylinder head.  Use new Intake manifold gaskets.

  5. When all assembled, fill and bleed the cooling system.

    1. Fill the expansion tank with a 50/50 mixture of new Fresh coolant and distilled water.  Use the same type of coolant that is already in the system (while you may have a favorite brand, the important part is the color, which tells what type of coolant it is).
    2. Open the bleeder screw/plug of the top of the thermostat housing (right next to the temp sensor), by inserting a screwdriver straight down from above.  Do not remove the screw, just loosen it a couple turns.
    3. Start the engine and let it idle.
    4. Fill the expansion tank as the coolant level lowers.
    5. Watch the area at the base of the bleed screw on the thermostat.  You will likely initially see nothing, then bubbles and then, eventually, coolant.
    6. When coolant is coming from the bleed hole, close the bleed screw (not tightly).
    7. Keep an eye on the coolant level in the expansion tank and assure that there is no overheat warning in the instrument cluster.  If you have an OBD-II scan tool that allows live engine data reading you can watch the actual temperature.
    8. Alternate between bleeding, running the engine and adding coolant until the temp and the coolant level have stabilized and there are no more air bubbles coming from the breeder.

To purchase the parts for this repair, as well as all of your MINI parts needsVisit eEuroParts.com


Posted in DIY How-To, Mini

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