How To Replace The Water Pump And Thermostat On A BMW N54 Engine (335i, Z4, X6, & More)

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Electric water pumps are a point of contention. They tend to fail more often than their mechanical counterparts, yet at the same time offer benefits over the more simple, mechanically driven ones. This statement holds true for the electric water pump on the BMW N54 engine. 

A very common job to need to tackle on any BMW with the N54 engine is the electric water pump. This water pump usually doesn't fail mechanically, rather it fails electronically. When this happens, it's common to run into some obvious symptoms. Luckily, a failing water pump is easy to diagnose and replacement is a long (but simple) DIY procedure. 

 

Symptoms of a failing BMW N54 water pump:

Symptoms of a failing BMW N54 water pump are pretty easy to spot. None of them should be overlooked as a water pump that has completely failed can cause irreparable damage to your engine. 

  • Overheating (you can tell by visually inspecting or by dash warnings)
  • Cooling fan running on high constantly
  • Car going into limp mode
  • BMW N54 water pump fault codes
    • Fault code: 2E81
    • Fault code: 2E82

For these specific water pumps, typically it's the motor or the motor controller that fails. This tends to happen between 55,000 and 60,000 miles; however, it's been reported to happen much sooner as well as last much longer. 

 

BMW N54 failed water pump diagnosis:

To diagnose if your water pump is the culprit of your symptoms listed above, the easiest way to do so is to use an OBDII scanner. All you need to do is connect it to your OBDII port and check for the fault codes specific to the water pump. 

One additional way to test if it's actually your water pump is to use a multimeter to check that the pump itself is receiving power and has a proper ground. 

 

N54-equipped BMW models applicable:

  • 2007-2010 BMW 335i
  • 2009-2010 BMW 335i xDrive
  • 2011-2013 BMW 335is
  • 2008-2010 BMW 535i
  • 2008 BMW 535xi
  • 2009-2010 535i xDrive
  • 2008-2010 BMW 135i
  • 2011 BMW 1M Coupe
  • 2009-2015 BMW Z4
  • 2007-2008 BMW 335xi
  • 2008-2010 BMW X6
 

Although the process is similar for the BMW X6, it will require a different kit as it has a different thermostat. You can find the kit for the X6, here

 

Tools needed to complete N54 water pump replacement: 

 

Optional tools to complete N54 water pump replacement:

 

Parts needed to complete N54 water pump replacement: 

 

BMW N54 Water Pump Replacement Torque Specs:

  • M8 water pump bolts
    • Steel = 15 N⋅m
    • Aluminum = 8 N⋅m
  • Sway bar mounting nuts
    • 21 N⋅m

 

BMW N54 Water Pump and Thermostat Replacement Process

Step 1: Remove the intake cowl

Using your T20 socket, remove the plastic screws. After those are removed, you can use the rivet pliers to pull the centers of each rivet. Once those are pulled, you can use a screw driver to pry each one up. 

We recommend placing the centers back in the rivets so you don't lose them. 

BMW N54 Water Pump Thermostat Replacement Intake Cowl

 

Step 2: Remove the cooling fan

To remove the cooling fan, you need to first remove the coolant hoses and move any electrical connectors out of the way. 

The fan is held in place by two T25 self tapping screws. 

BMW N54 Water Pump Thermostat Replacement  Cooling Fan

 

Step 3: Remove the intercooler

Unfortunately, the intercooler has to come off. Luckily, it's simple to remove as it's only held in place by two T25 screws. This will gain you access to the radiator drain screw. 

BMW N54 Water Pump Thermostat Replacement Intercooler

 

Step 4: Remove the radiator drain screw and drain coolant

This is where the job starts to get a little messy. Using a flat-head screwdriver, remove the drain screw on the bottom of the radiator. Make sure you have your drain pan in place to catch as much coolant as you can.

BMW N54 Water Pump Thermostat Replacement Radiator Drain Screw

 

Step 5: Remove Coolant Hoses

Now's the time to remove the coolant hoses from the radiator. A lot of coolant is going to drain here, so make sure you have your drain pan ready and that it's empty enough. A pick tool is handy at this point to remove the quick disconnects from the hoses. 

BMW N54 Water Pump Thermostat Replacement Coolant Hoses

 

Step 6: Lower the sway bar mounts 

To gain access to your water pump and thermostat, you're going to have to get your sway bar out of the way. To do so, remove the four 13mm nuts that hold the sway bar mounts in place. Once those are off, the sway bar should just lower out of the way. 

BMW N54 Water Pump Thermostat Replacement Sway Bar Mounts

 

 

Step 7: Disconnect the water pump and thermostat

There are numerous hoses and connectors on both the water pump and the thermostat. Simple remove these and disconnect the crossover hose that goes from the water pump to the thermostat. 

BMW N54 Water Pump Thermostat Replacement

 

Step 8: Remove the thermostat

To get the thermostat out, you need to remove the two 10mm bolts that fasten the water pump to the thermostat. This is where extensions for your ratchet come in handy if you have them. 

There will still be coolant in the thermostat, so be ready to catch any as it drains. 

The thermostat should come right out at this point as long as you have disconnected all of the hoses and connectors from the previous steps. 

BMW N54 Water Pump Thermostat Replacement

 

Step 9: Remove the water pump

The water pump is the last part you need to remove. It's fastened to the engine block using three E10 bolts. There is one bolt up top, and two bolts down below. 

BMW N54 Water Pump Thermostat Replacement Removal

 

Step 10: Reverse process for reinstallation

The installation process goes back together just as easy as it came apart. Just follow these steps in reverse. Gareth has some handy pointers that can only be described with video, so if you become hung up, be sure to reference the video above. 

One thing to note is the difference between the new water pump and the old. The new water pump doesn't feature rubber bushings and instead uses a solid aluminum housing. It comes with new steel bolts which are safe to use on the aluminum engine block. You should not use these bolts if you have an engine with a magnesium engine block. 

BMW N54 Water Pump Comparison

 

Step 11: Filling and bleeding the cooling system

The BMW N54 cooling system has a conveniently engineered filling and bleeding process. Using your no-spill funnel, mix your coolant and distilled water to either a 50:50 or 60:40 ratio and begin filling your reservoir. Once you have it filled, you can start bleeding your system.

To bleed the system, you first put the car into accessory mode. Once it's in accessory mode, turn the heat in your car to high, and turn the fan up as high as it will go. Once you do that, put your foot on the accelerator pedal for 10 seconds. Doing this activates the self-bleed function. 

After that, the process is autonomous. Let this process go for 10-12 minutes; you should see some action in your coolant funnel while it completes the self-bleed. This is a good time to look under the car and inspect for leaks. If it's going to leak, it will do so now. 

BMW N54 Water Pump Thermostat Replacement Coolant Fill

 

And that's it, your water pump is replaced and your cooling system should be functioning like new. 

If you have any questions or comments about the process, leave them in the comments below and we will get back to you. If you're interested in more BMW N54 and E90/E92 content, you can visit our new BMW E9X Hub

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