This article gives detailed instructions on replacing the water pump in a BMW E9x 3 series vehicle. Even though we used a 2011 335i to perform this repair, this article can be applied to any 2006-2013 3 series vehicle (except M3) with minor modifications to the repair steps.
A BMW E90 water pump replacement can save the experienced home mechanic a ton of money by avoiding the repair shop or dealership.
There are some repairs the home mechanic can do to their BMW that can really save them a lot of money…a BMW E90 water pump replacement is one of them. Just the sound of “water pump replacement” brings tears to many 2007-2013 3 series owners eyes – it usually means a $1000 plus trip to the repair shop. But if you are a home mechanic that is fairly good with tools and are comfortable under a raised vehicle, a BMW E90 water pump replacement can easily be done for a fraction of the price.
When the 5th generation BMW E9x 3 series was launched in 2006 it contained a new electric water pump. Unlike the belt driven versions from older 3 series models, the newer electric water pump is operated by the engine’s control module (DME). This was a much welcomed (and needed) advance in technology since the water pump could now be more accurately controlled creating a more efficient engine. It was also a much welcomed change by mechanics who could now accurately diagnose water pump issues via a diagnostic scanner rather than by conjecture.
The downside to an electric water pump has been two fold for BMW owners; electric water pumps are substantially more expensive than their mechanical counterparts, and replacing them is more time consuming. This has created a “perfect storm” when the water pump fails; a very expensive part that requires a lot of labor to replace. BMW E90 owners have consistently reported estimates well over a $1000 for replacing the pump.
A BMW E90 water pump replacement is challenging due to the tight confines in which it resides. It is mounted on the lower right side of the engine, partially tucked behind the vehicle’s front sway bar and steering rack. In order to safely extract it, the E90’s cooling fan and thermostat must be removed first. The good news is the BMW E90’s cooling fan is easy to remove; with a little patience a BMW E90 water pump replacement is a very “doable” repair for the home mechanic with intermediate skills.
Now is also an excellent time to flush your engine’s cooling system…especially if you find any signs of mineral deposits or scaling while replacing the water pump. It is recommended that the cooling system in your BMW E90 is flushed every 24 months. For more information on flushing your system, please see our article BMW E90 Coolant System Flush.
1. Water pump (required) – The BMW E90 water pump is electronic, which means it must be manufactured to very high standards to avoid catastrophic failure. Cheap generic water pumps from obscure manufacturers have a high failure rate and should be avoided at all costs. The following replacements are all OEM quality…we give you several choices based on your brand preference and budget.
2. Engine coolant (required) – You will lose about 1 gallon of coolant during this repair, which equals 1/2 gallon of Genuine BMW Anti-Freeze/Coolant mixed 50/50 with distilled water. NEVER USE any type of water other than distilled in your coolant system; even filtered bottled water can leave mineral deposits inside your radiator and hoses causing a system failure. For more information on how using the wrong water in your coolant system can destroy it, please see our article BMW E60 Coolant Flush – 2004-2010 5 Series – N52 6 cyl..
3. Thermostat (optional) – Since the thermostat will need to be removed to do this repair, now is an excellent time to replace it. Keep your engine coolant flowing like its in a new engine by installing a fresh thermostat with your water pump.
4. Radiator flush (optional) – Since all of the coolant will need to be removed from your E90 to do this repair, now is an excellent time to flush the system. Flushing the coolant system should be done every 24 months to remove mineral deposits and scaling inside the hoses and radiator of your vehicle. The BMW Repair Guide only uses Liqui Moly Radiator Cleaner in its vehicle’s; it is excellent at removing mineral deposits and will leave your coolant system sparkling clean without damaging hoses or metallic parts.
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In order to remove the BMW E90 water pump, the coolant must be drained first and several parts cleared out of the work area. You do not need to remove the radiator to perform this repair.
- Jack and support the vehicle at all wheels. You cannot correctly drain the coolant system if you only raise the front of the vehicle…it must be level. For more information on jacking and supporting you BMW please see our article BMW Jacking and Supporting for Repairs and Maintenance.
- Remove the front belly pan from underneath the engine. It is usually held in place with phillips head screws.
- If you are working on a turbocharged E90 3 series (like the 335i we are using for this article), please proceed to the next step to remove the turbo intercooler from the bottom of the radiator. If you are not working on a turbocharged engine, please proceed to step 5.
- To remove the turbocharger intercooler, use a T25 torx bit to remove the two intercooler mounting screws. Release the metal locking clips securing the left and right charge pipes and remove the intercooler from the vehicle.
- Remove the cap from the coolant expansion tank. The cap must be removed or else the coolant system will not drain properly in the next step.
- Using a large flat blade screwdriver, remove the drain plug from the bottom left side of the radiator. Allow the radiator to thoroughly drain.
- When the radiator is completely drained, replace the plug. DO NOT wait to replace the plug! We cannot tell you how many mechanics get distracted at the end of the repair and forget to replace it.
- Next, the cooling fan must be replaced. Start by removing the engine oil cooler from the bottom left side of the cooling fan. It is simply held in place with one T25 torx screw. Gently push the cooler back and out of the work area.
- Moving back to the engine bay, remove the two torx bolts anchoring the intake duct to the suction hood at the front of the car. Unsnap the intake duct from intake muffler and remove it from the vehicle.
- Release the locking clip on the expansion tank vent hose and remove it from the expansion tank. Unclip it from the top of the radiator and gently lay it out of the way.
- Unplug the cooling fan’s wiring harness from the left side of the fan.
- On the left side of the cooling fan, find the fan’s plastic release tab. While pressing on the release tab with your finger (see image below), pull up on the cooling fan until it slides out of the engine. Remove the cooling fan from the vehicle.
- You now have clear access to the water pump.
In order to extract the water pump from the vehicle, the thermostat needs to be removed first. Once the thermostat is cleared out of the way, the water pump will easily slip out from the front of the vehicle. Remember that even though the radiator has been drained, there is still coolant in many of the hoses. Keep your face away from hoses when disconnecting them from the thermostat and water pump.
- Locate the heater return line that runs across the front of the vehicle. We highly recommend loosening this hose to avoid breaking it when removing the water pump. Use a T30 torx bit to remove the two screws anchoring the return line to the
- Remove the lower radiator hose from the front of the thermostat by using a straight metal pick (or small flat blade screwdriver) to release its metal locking clamp and pulling it free. You may have to rock the fitting back and forth to get it off of the thermostat – they tend to get stuck over time.
- Next, remove the heater return line from the right side of the thermostat by releasing the metal locking clip and pulling it free.
- Move under the vehicle and locate coolant line that runs from the rear of the thermostat to the water pump. Use a flat blade screwdriver to loosen its hose clamp, then pull it free from the thermostat.
- The final cylinder head coolant hose cannot be accessed until the thermostat is rotated away from the engine (step 8 below).
- Locate the thermostat’s two mounting bolts on the lower left side of the thermostat. Use a 10mm socket wrench to remove the two bolts. The thermostat is now free an can be rotated forward.
- Grasp the front of the thermostat and rotate it so the rear cylinder head coolant line can be accessed.
- Use a screwdriver to loosen the cylinder head coolant hose clamp. Pull the hose free from the thermostat.
- The thermostat can now be removed from the front of the engine. Use a small flat blade screwdriver to release the thermostat’s electrical plug and pull it free.
- Remove the thermostat from the vehicle.
- Locate the water pump attached to the lower right side of the engine block. The BMW E90 water pump is attached with three bolts…two on the bottom and one on the top of its mounting bracket.
- Using an E14 external torx socket, remove the lower two mounting bolts.
- Moving to the top of the water pump, remove the upper mounting bolt.
- Next, the power steering fluid line needs to be removed so the back of the water pump can be accessed. Use a 17mm open end wrench to counter hold the mounting stud while using a 10mm open end wrench or socket to remove the nut (see image below). Gently move the power steering fluid line out of the work area.
- You now have clear access to the back of the pump. Use a flat blade screw driver to finish removing the thermostat hose from the back of the water pump.
- Rotate the pump forward so you can access its electrical connection. Press the locking tab down with your finger while pulling the plug free from the pump. If the plug is stuck, gently use a screwdriver to pry it off while depressing the locking tab.
- Rotate the pump again so the engine block coolant hose can be accessed. Use a flat blade screwdriver to loosen the hose clamp and pull the hose free from the water pump.
- The pump is free and can now be removed from the front of the engine.
Installing a new water pump is simply the above steps in reverse with no special procedures other than what you have already done. We have included a handy checklist with the exact steps needed to install the new pump and reassemble the vehicle, along with critical torque values for the thermostat and water pump mounting bolts.
BMW E90 Water Pump Replacement – Reassembly Checklist
***The following steps were performed on a 2011 335i…other models may vary.
- Install the new pump into the front of the vehicle making sure it is oriented in the correct position.
- Attach the engine block coolant hose to the back of the pump and tighten its hose clamp.
- Plug the pumps electrical connection back in. Make sure it clicks into place.
- Install the thermostat coolant hose onto the back of the pump. Make sure it is installed in the correct position so it lines up with the back of the thermostat! Tighten the hose clamp.
- Attach the power steering fluid line bracket back onto the frame of the vehicle and tighten its nut until snug.
- Install the pumps three E14 mounting bolts and torque to 25 Nm (18 Ft-lb).
- Plug the electrical connector back into the thermostat.
- Connect the cylinder head coolant hose back on to the thermostat and tighten its hose clamp.
- Rotate the thermostat back into the engine.
- Install the two thermostat mounting bolts and torque them to 6 Nm (4.5 ft-lb).
- Reinstall the water pump hose on the rear of the thermostat and tighten its hose clamp.
- Close the locking clip on the heater return hose and push it onto the thermostat until your hear it click into place.
- Close the locking clip on the lower radiator hose and install it back onto the thermostat. Make sure you hear it click into place.
- Install the heater return line back onto the frame of the vehicle using the two T30 mounting screws.
- Install the cooling fan back into the front of the vehicle.
- Reinstall the cooling fan plug.
- Close the locking clip on the expansion tank vent hose and install it back on the expansion tank.
- Reinstall the intake duct.
- Reinstall the transmission cooler onto the back of the cooling fan.
- ***If you are working on a turbocharged engine, reinstall the intercooler. MAKE SURE you hear the charge pipes click into place on the intercooler..loose charge pipes will cause a rough idle and check engine light.
- Reinstall the front belly pan.
- Refill and bleed the coolant system (see Section 4 below).
It is very important that the coolant system is refilled and bled correctly to remove any air pockets. Not properly purging the system of air can cause the engine to overheat. Fortunately the BMW E90 has an automated coolant bleeding system that makes the process very easy. Always use Genuine BMW Anti-Freeze/Coolant mixed 50/50 with distilled water.
- A battery charger should be attached to your vehicle while refilling the system and purging it of air. The reason for this is you will be drawing current from the battery for about 15-20 minutes without the engine running.
- Attach a battery charger to the battery terminals in the engine compartment as shown below and put it on its lowest setting. NEVER attach a battery charger directly to the battery itself in the rear of the vehicle…you could cause catastrophic damage to sensitive electronics if you do.
- First, the auxiliary water pump needs to be activated to circulate the coolant through the system while you fill the expansion tank. The auxiliary pump is activated when the vehicle’s driver’s side heater is set to its maximum setting and the blower is at its lowest setting.
- Start by turning on the ignition so the air conditioning settings can be changed. DO NOT start the car…just turn on the ignition!
- Turn the heat all the way up on the driver’s side temperature controller.
- Turn the blower down to its lowest setting.
- The auxiliary pump is now activated. Move to the front of the vehicle.
- Open the bleed screw on the expansion tank with a large flat blade screw driver.
- Start filling the expansion tank with a 50/50 mixture of Genuine BMW Anti-freeze/Coolant and distilled water. When the tank fills up, stop pouring until the level drops. When the coolant level in the tank stops dropping and starts to come out of the bleed screw, stop pouring. Tighten the bleed screw and replace the cap on the expansion tank.
- Move back inside the vehicle.
- Turn the vehicle off. You must turn the vehicle off to reset the system before initiating the automated bleeding process.
- Turn the ignition back on. DO NOT start the engine…just turn on the ignition. Hold the accelerator down with your foot for 12 seconds and then release. This will initiate the automated bleeding process.
- Move to the front of the vehicle. You should be able to clearly hear the water pump running as it bleeds the coolant system.
- The automated bleeding process lasts approximately 12 minutes. After it is finished you can start the vehicle and check for normal operation.