The E9x family of BMW 3-series cars (among others) came with an all new line of engines, beginning with N rather than the previous M and S model designations. The 6 cylinder power plants have a few design features to make them more efficient in terms of power, fuel consumption, and emissions. However, like most modern engines, there is a pretty glaring trouble point, the water pump. These BMW’s utilize an electric water pump to allow computer controlling of coolant flow, rather than an engine speed dependent pump that saps drive power to run.
E90 electric water pumps tend to have a relatively short life span, and if yours fails you will end up on the side of the road (at best), with the threat of engine damage if the driver doesn’t take notice of an overheating engine (at worst). There are three kits for these cars:
328i xDrive 2009-2011
+ BMW 1 Series M 2011-2011
+ BMW 135i 2008-2010
+ BMW 335i 2007-2010
+ BMW 335i xDrive 2009-2010
+ BMW 335is 2011-2011
+ BMW 335xi 2007-2008
+ BMW 535i 2008-2010
+ BMW 535i xDrive 2009-2010
+ BMW 535xi 2008-2008
335i xDrive 2011-2013
You can tell the difference by simply looking at them. The non-turbo cars get a full metal water pump where the turbocharged N54/N55 6 cylinders use a two part composite/aluminum pump. If you are doing this job on an N51/N52 car, then you will notice the thermostat coming out is aluminum. It seems that part is now only available in plastic composite. The 135 and 335s came with a plastic composite thermostat from the factory.
Unfortunately, both of these pumps only last around 50-80k miles from the factory, and since they are a little tricky to replace, can cost a huge amount of money to do preemptively at the dealer. eEuroparts carries a water pump kit that fits these 6 cylinder engines, and contains everything you need to keep your car reliable and happily on the road.
The eEuro E90 Electric Water Pump Kits for N51, N52, N52 Engines
The kit contains everything you need to effectively change the water pump on your BMW at a much more effective price point. The Pierberg water pump is the original equipment brand, at a significant savings over Genuine BMW. The thermostat is a German made Wahler with integrated temperature sensor, another reputable company that supplies many car makers with their OEM parts. We also carry the OES Behr unit if you like. This eEuro E90 Electric Water Pump Kit also features the water pump-to-thermostat hose, some high quality Genuine BMW hose clamps (trust me, you don’t want to use substandard hose clamps), and the very important E12 aluminum bolts that are specifically one-time-use. Reusing the water pump bolts is a risky situation, especially since the location is tricky to get to if you snap one of them off. German Made ROWE coolant and thermostat bolts are also included.
The eEuro E90 Electric Water Pump Kits for N54/N55 Turbo Engines
These kits are basically the same, with a few subtle variations in part numbers. The pumps are still OES, although BMW changed suppliers for the redesign, so our OES pumps are VDO rather than Pierberg. There are subtle changes in the thermostat as well between the N54 kit (100K10365), and N55 kit (100K10324). Also included are the hose, clamps, hardware, and ROWE coolant.
If you are mechanically inclined and are able to do basic mechanical tasks, this job is DIY capable. It is a little finicky, so for the average DIYer, put aside a day for this job. Savings on doing this yourself with the eEuro E90 electric water pump kit can go past $1000 depending on the shop. With the car safely in the air, you will see the pump behind the sway bar and power steering gear. The first thing you want to do is disconnect the power steering cooling line from the bracket and pull it down out of the way. Continue on by disconnecting the sway bar bushings from the subframe and let it swivel down. Bungee it out of the way to keep from whacking your head on it repeatedly.
Installing the kit:
With access, you can go about removing the hose clamps to drain the coolant into a catch can. The bolts are E12 inverted torx, and need to be replaced because they are one use only. Keep in mind some of the hose clamps are quick connects and some are standard hose clamps. You won’t be able to remove all the hoses before pulling the pump down because there is no access to the upper clamps with the pump in place. Just remember the orientation of the pump as you remove it so you don’t twist the hose on re-installation. The thermostat will be in view above the pump. Take care to note the way the electrical connection clips work by looking at the new parts in your eEuro kit. Here’s the coolant bleeding procedure:
Fill expansion tank with BMW coolant (50/50 mix), leave the cap off. With the key to the “on position” (no engine running), turn your heat all the way up with fan on the lowest speed without turning it off. Then hold gas pedal all the way to the floor (you’ll feel a click in the pedal) for about 10-15 seconds. You should hear the pump running, which will bleed air out of the system. Remember to make sure your tank is full of antifreeze! [thanks seb for that tip! -ed]