This article gives detailed instructions on replacing the power steering pump in a BMW E46 3 series vehicle. Even though we used a 2004 325ci to perform this repair, this article can be applied to any 1998-2006 vehicle with minor modifications to the repair steps.
If your 3 series steering wheel suddenly becomes extremely difficult to turn while the vehicle is running, then you most likely are in need of a BMW E46 power steering pump replacement.
The BMW E46 3 series was produced from 1998-2006, and has been labeled by many automobile enthusiasts as an icon. Unfortunately most E46 3 series vehicles still on the road are running with original parts that are beginning to fail…especially the mechanical ones.
One part of particular concern is the BMW E46 power steering pump. The accessory belt driven power steering pump is located near the bottom of the engine on the left side of the vehicle. Since the power steering system on a BMW E46 is hydraulic, it requires a pump to create high fluid pressure in the steering rack. The high pressure fluid in the steering rack pushes against a piston when you rotate the steering wheel, making it easy to turn the front wheels.
When the power steering pump fails you will know it immediately – turning the steering wheel becomes excruciating difficult at low speeds. BMW E46 power steering pump failure is usually caused by the pulley shaft separating from the internal impeller causing it to spin freely. Sometimes the pulley shaft can seize creating a particularly dangerous situation. A frozen power steering pulley can literally destroy the main accessory belt causing catastrophic damage to the engine.
The good news is that the replacement parts are relatively inexpensive for this “do it yourself” repair. The bad news is you will need to jack the front of your vehicle up to access the pump; if you can get past working under a raised vehicle, you can save a ton of money doing this repair yourself.
Determining what parts you need
In most circumstances, all you will need to do this repair is a new pump. Unless you experienced catastrophic failure of the pump that caused its shaft to seize up, the original pulley and accessory belt can be reused. It is often suggested that a power steering pump replacement creates an opportunity to replace the original BMW plastic pump pulley with an stronger aluminum one. While we do agree with this idea, it is not mandatory. If your plastic pump pulley is in excellent shape with no visible chips or cracks, it is perfectly acceptable to reuse it.
We also suggest replacing your accessory belt if it is showing signs of age or is nearing the end of its service life. Since you will need to pull off the accessory belt to replace the power steering pump, it is a great time to replace it.
1. Power steering pump (required) –There were several different power steering pumps manufactured depending on the production date of your vehicle. We give you several high quality options below.
2. Power steering fluid (required) –Always use a superior grade power steering fluid in your BMW. There is very little savings in buying cheap inferior fluid.
3. Power steering pulley (optional) – The original power steering pulley on your E46 is made of plastic. Over time it can become chipped or cracked causing belt failure. Now is a great time to upgrade to an aluminum pulley while installing a new pump.
4. Accessory belt (optional) – Now is a great time to replace your main accessory (serpentine) belt since you will need to remove it for this repair.
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In order to properly remove and reinstall the accessory belt on the power steering pulley, the vehicle’s cooling fan must be removed. It is very easy to remove and install the accessory belt on a BMW E46 3 series from the top of the engine with the fan removed. Trying to remove and reinstall the accessory belt from the bottom of the engine is extremely difficult and we discourage our readers from attempting to do it this way.
- Begin by removing the air box assembly. Use a 10mm nut driver or socket wrench to remove the two air box mounting bolts on the left side of engine compartment.
- Disconnect the Mass Air Flow (MAF) sensor.
- Using a flat blade screwdriver, loosen the hose clamp connecting the air intake boot to the air box.
- Remove the air box from the engine compartment.
- Next, remove the upper coolant hose from the thermostat by releasing the snap clip with a flat blade screwdriver. Pull the hose off of the thermostat. Release the clips from the hose where it attaches to the coolant reservoir. Remove upper coolant hose from vehicle.
- Use a trim tool to remove the three plastic rivets attaching the air inlet assembly to the front of the vehicle.
- Remove the air quality sensor and the wiring harness connection from the right side of the fan shroud.
- Remove the two fasteners anchoring the fan shroud to the front of the vehicle. These fasteners are often lost or changed over the years, so there may be screws holding the fan shroud…or it may be plastic rivets. We had both.
- Carefully remove the plastic fan shroud, paying attention to the fan blades during removal. It helps to have someone underneath vehicle pressing in on bottom of shroud so it clears the fan blades. Once bottom of shroud is clear of blades, it will pull out smoothly.
- With the fan shroud removed, you can now access the fan clutch nut. Use a BMW fan clutch tool to loosen the fan clutch nut. Remember…the fan clutch nut is a reverse thread! You must turn the nut clockwise (to the right) to loosen it. If you are able to loosen the nut with the tool, remove the fan and proceed to step 12. If you cannot loosen the nut with the tool, go to step 11.
- It is very common for the fan clutch nut on BMW E46s to seize and not be removable with the fan clutch tool. Lack of maintenance and poor maintenance practices (not greasing nut during prior repairs) causes stripped and seized nuts, making them virtually impossible to remove. Many nuts will show the battle scars of mechanics attempting to remove them…a telltale sign that trouble lingers ahead. Your only option at this point is to remove the fan clutch bolts and remove the plastic cooling fan. Use a T30 torx bit to remove the three fan clutch mounting bolts. Remove the fan from the vehicle.
- Remove the plastic cover off of the tensioner pulley. The tensioner pulley is located near the middle of the engine above the power steering pump.
- Using a T50 torx bit, turn the pulley clockwise until the accessory belt loosens. Reach down and pull the accessory belt off of the tensioner pulley. The belt can now be removed from the power steering pulley.
- Jack and support the front of your vehicle using the four corner wheel stand method as shown in our article BMW Jacking and Supporting for Repairs and Maintenance.
- Locate the power steering pump. It is on the left side of the engine below the alternator.
- Remove the cap from the power steering fluid reservoir. This will allow the system to properly drain.
- Use a flat blade screwdriver to loosen the hose clamp connecting the suction hose to the pump. Remove the hose from pump allow to drain completely into a 5 gallon drain pan. Be careful…the fluid comes out quickly. Make sure you are not underneath the suction hose when you disconnect it from the pump, or you will get a face full of power steering fluid and a bad case of acne the next morning. ***Option – you can use a fluid removal pump or a “turkey baster” to empty the reservoir first (before removing the suction hose) if you don’t want to get splattered with fluid.
- Use a 17mm crows foot socket to remove the pressure hose from the pump. Make sure to have a drain pan positioned under the hose to catch the small quantity of fluid still in the pump. You can use a 17mm open end wrench if you wish, but a crows foot is easier due to the confined space. The crows foot will also allow you to torque the nut to spec at the end of the repair.
- Remove the belt from the power steering pump pulley.
- There are three bolts anchoring the power steering pump to the engine. There are two mounting bolts that anchor the pump to the front of the engine; one bolt is on the back of the pump and one is on the front. The third bracket bolt anchors the pump to the side of the engine block and is also located at the rear of the pump. The following is an image of our new replacement pump showing the three mounting points for the pump.
- Starting at the rear of the pump, use a 13mm socket wrench with extension to remove the bracket bolt.
- Use a 13mm socket wrench to remove the rear pump mounting bolt.
- Moving to the front of pump, use the 13mm socket wrench to remove the front pump mounting bolt. A low profile flex head ratchet comes in very handy in this step.
- Remove the pump from the vehicle. It is easiest to remove from the rear of the sway bar. Be careful not to tear the tie rod boot when removing (not shown in image).
- Notice the pump we removed is completely destroyed. The pulley shaft has separated from the pump. This could have caused disastrous consequences if left unfixed.
When doing a BMW E46 power steering pump replacement, it is recommended that you upgrade from the stock plastic pulley to a newer metal one. This is only a recommendation and not a requirement; if your original plastic pulley is in good shape (free of chips, cracks or scrapes), then reusing it is perfectly acceptable.
Removing and installing the pulley on an E46 power steering pump raises its own set of challenges; since the pulley spins on a shaft, trying to remove the bolts without somehow locking the pulley from spinning can become a lesson in futility. Further compounding the issue is that trying to remove and install the pulley while the pump is still on the vehicle is next to impossible. Don’t trust the photos you see online! You will never be able to torque the pulley bolts properly with the pump installed in the car.
The good news is the pulley bolts are at a relatively low torque (22Nm – 16ft lb) so removing and/or installing them is fairly easy. The trick is to immobilize the pulley without breaking it. This is easily done with an old accessory belt (or an inexpensive new one if you don’t have one lying around) and a table vice. Never attempt to remove or install pulley bolts with an impact wrench. This can cause damage to the pulley…it also may cause excess stress on the pump shaft leading to pump failure.
- Cut any “six ribbed” accessory belt you can find in half with a pair of shears. If you are replacing the accessory belt during this repair, use your old one. If you do not have an old belt, run to your local auto parts store and buy a cheap one…they have plenty of them for under 20 bucks.
- Wrap the accessory belt around the pulley twice and cut off excess.
- Place the pulley and pump into a table vice. Slowly tighten vice until pulley is secure. DO NOT overtighten. DO NOT allow vice jaws to touch pulley. They should only be pressing in on belt (see image below).
- Remove the three pulley bolts with a 13mm socket wrench.
- Carefully pull the old pump free of pulley. Leave the pulley in the vice.
- Install the new pump on the pulley and hand tighten the bolts. Torque bolts to 22Nm (16 ft-lb).
- Install the new pump onto the engine with the two mounting bolts and bracket bolt. Torque all three bolts to 22Nm (16 ft-lb). DO NOT over-torque these bolts or they will strip.
- Reinstall the pressure hose and hand tighten the M16 bolt. Torque the bolt with a 17mm crows foot socket to 40Nm (30 ft-lb). This is a lot of torque…proceed carefully. Always double check the torque value on your wrench so you don’t make any mistakes.
- Reinstall the suction hose and firmly tighten the hose clamp.
- Loop the accessory belt back around the power steering pulley. From the top of the engine, reinstall the accessory belt back on the tensioner pulley (section 1, step 13) . Pay particular attention to the belt where it loops around the water pump pulley…this is usually where the belt falls off during installation.
- Reinstall the cooling fan. If you were able to remove the fan from the water pump with the fan clutch tool (section 1, step 10), apply a liberal amount of grease (not WD-40…but any thick paste grease) to the fan clutch nut; we do this so the fan can be easily removed in future repairs. Reinstall the fan. Remember…the plastic cooling fan has reverse threads! Turn the nut counterclockwise (left) to tighten.
- If you had to remove the plastic cooling fan by removing the fan clutch bolts (section 1 step 11), you will need to reinstall the bolts. First…MAKE SURE PLASTIC FAN is installed in the right direction! If not you will be pulling air out of the engine instead of blowing it in. Reinstalling the bolts is a bit tricky…we advise looking for the threaded blocks on the fan clutch to guide you in. Putting the bolt on the torx bit and extension and then installing is a lot easier than trying to thread them in by hand. Be patient, once you figure out how to do them they go in easy. Use a low torque wrench to tighten the fan clutch bolts to 10Nm (7 ft-lb).
- Reinstall the fan shroud, being careful it doesn’t get hung up on the plastic cooling fan. DO NOT force the fan shroud down. If the fan shroud is not installing properly, most likely the plastic tab on the bottom of the shroud is not lining up with with the plastic bracket on the bottom of the radiator (see following images). This step is best done with the aid of a helper who can guide the fan shroud into the bottom radiator bracket while someone pushes from the top.
- Reinstall the upper coolant hose by closing the clips and pushing them on to the thermostat and coolant reservoir until you hear them “click”. You may have to put some muscle into them to get them to go on. MAKE SURE YOU HEAR THE METAL hose clips “click” when reinstalling the hose – this means the connections are secure and the clips are seated correctly. The connections to the fluid reservoir can be a pain…so use patience. This is very important…a hose that is improperly installed will leak coolant and quickly become a disaster. Since you have introduced air into the cooling system, you will need to quickly bleed the system. This is a very easy procedure and will be done below in section 4.
- Reassemble the rest of the vehicle.
- After you have finished reassembling the vehicle, fill the power steering reservoir with an approved power steering fluid.
- Start the vehicle. Leave it running through the next steps.
- You will need to bleed out any air that is trapped in the coolant lines from removing the top coolant hose. Loosen the bleeder screw on the top of the coolant reservoir to purge any trapped air out of the system. When a steady stream of coolant runs out of the bleeder screw, you can tighten. Be sure to check your coolant level just to make sure you didn’t lose any during the repair. Top off the coolant as necessary (use only a BMW approved coolant – the Repair Guide only uses Genuine BMW Coolant/Anti-freeze 67704 mixed 50/50 with distilled water.
- Next you will need to bleed the power steering unit. This is a very simple procedure: With the engine running, sit in the driver seat and turn the steering wheel all the way to the right until it stops. Then, turn the steering wheel all the way to the left until it stops. Repeat this operation two more times. The steering wheel should now turn smoothly with little effort. You have successfully bled the steering system.
- Turn the engine off and take one last look under the vehicle to make sure none of the power steering lines are leaking. Check the engine bay and make sure there are no leaks in the upper radiator pipe and everything looks secure.
- Check the power steering fluid level and top off if necessary.