This article gives detailed instructions on replacing the starter motor in a BMW E46 3 series vehicle. Even though we used a 2000 323i with the M52 engine to perform this repair, this article can be applied to any 1998-2006 vehicle with minor modifications to the repair steps.
A BMW E46 starter replacement may be necessary if your 1998-2006 3 series engine is struggling to turn over.
One of the most often used mechanical parts in your BMW is the engine’s starter motor. Depending on your driving habits, the starter motor in your BMW E46 3 series can be used over a thousand times a year. And like all regularly used mechanical parts in your vehicle’s engine, the starter motor has a finite lifespan and will eventually fail.
The BMW E46 starter is simply and electric motor that rotates the engine’s crankshaft when the ignition key is turned. It contains an electromagnet which when energized, pushes out a pinon gear on the end of a shaft. This pinion gear engages the engine’s flywheel which in turn spins the crankshaft. When the engine “turns over” the ignition key is released, which causes the shaft to retract and the starter motor to shut off.
Due to age and general wear and tear, the internal components of the starter motor can begin to fail. The most common symptom of a failing BMW E46 starter motor is the vehicle becomes difficult to start (or won’t start at all)…even with a fully charged battery. In fact many 3 series owners mistakenly install a new battery in the vehicle when in reality they need a starter replacement. Another common symptom of a failing starter motor is a clicking sound when attempting to start the vehicle – this is caused by the starter shaft engaging the flywheel but unable to turn it.
Where is the starter motor on a BMW E46 3 series?
The starter motor in all 1998-2006 3 series vehicles is at the bottom of the engine underneath the intake manifold. We feel the easiest way for the home mechanic to perform a BMW E46 starter replacement is by removing the intake manifold. The starter motor can also be removed from underneath the vehicle, but this requires unbolting the transmission. This can be a major undertaking for the DIY mechanic working in his garage – removing the intake manifold to access the BMW E46 starter motor is a much more realistic approach and is the procedure covered in this repair article.
Don’t be intimidated by removing the intake manifold in this repair! If you closely follow our step by step instructions it is actually a relatively easy procedure. Most importantly it gives you a chance to replace the infamous intake manifold gaskets that are prone to vacuum leaks on the BMW E46 3 series vehicle.
1. BMW E46 starter motor (required) – There are many brands of starter motors on the market…we always recommend going with an OEM quality motor if longevity is important to you. Cheaper starter motors do not last as long as those from superior BMW aftermarket manufacturers.
Starter motor – Bosch 12412354693
Starter motor – Bosch 12412354709
2. Intake manifold gaskets (optional) – As discussed above, since you will need to remove the intake manifold to perform this repair, now is an excellent time to replace the gaskets. The intake manifold gaskets on you 1998-2006 3 series are a common source of vacuum leaks and should be replaced whenever possible.
Intake Manifold Gasket Set – Ajusa 11611436631
Intake Manifold Gasket Set – Genuine BMW 11611436631
3. Throttle body gasket (optional) – Another common source of vacuum leaks is the throttle bosy gasket. Since the throttle body will need to be removed for this repair, now is an excellent time to replace it.
Throttle Body Gasket – Genuine BMW 11611716174
Throttle body gasket – Genuine BMW 13547504728
Throttle Body Gasket – Genuine BMW 13547504729
4. Intake boot (optional) – One of the most common casualties when removing your intake system is the intake boot. Age and heat cause the intake boot to become brittle, literally causing it to crack during disassembly. Now is a great time to replace this inexpensive but but critically important part of the intake manifold.
Intake boot – Genuine BMW 13541705209
Intake boot – Genuine BMW 13541435627
Intake Boot – Genuine BMW 13541438761
Intake Boot – Genuine BMW 13541438759
8mm socket wrench
10mm socket wrench
13mm socket wrench
E12 external torx socket
Torque wrench- low range
Socket wrench – low profile dual head
Socket drive adapter
Blaster PB Lubricant
Hammer – ball-peen
In order to perform a BMW E46 starter replacement, the intake manifold must be removed. This should not be an intimidating process…in fact we urge home mechanics to look at this as an opportunity to install new manifold and throttle gaskets, as well as replace old vacuum lines that are prone to leaking.
For detailed step by step instructions on removing the intake manifold for this repair, please see our article BMW M52 Intake Manifold Removal – 1995-2000 3,5,7,Z3 Series 6 Cyl.
The BMW E46 starter motor mounting bolts are notoriously difficult to remove from the engine for two reasons; there is very little clearance to get a socket wrench squarely on the head of the bolts, and the bolts are usually seized from age. These two conditions can create a recipe for disaster if you are not careful…you can strip the mounting bolt heads. We have found the best method for removing the starter mounting bolts is to use a long 1/4″ drive swivel head ratchet, with a 3/8″ adapter and E12 external torx socket. The reason why you must use a 1/4″ socket wrench is that the head on a 3/8″ wrench is to large….it will not allow the torx socket to fit squarely on the head of the bolt. It is also important to use a long handle ratchet in order to get the proper amount of leverage to loosen the bolts. If used correctly as shown in the below steps, you will be able to safely extract the mounting bolts without any issues. If you need to order any of these tools prior to starting this repair, we have the same ones we used in the above tool list.
- Locate the BMW E46 starter motor. It is located at the rear of the engine.
- Use a 13mm socket wrench to remove the positive battery cable and alternator cable from the starter solenoid.
- Use an 8mm and 10mm socket wrench to remove the two wiring harness leads from the starter solenoid.
- Using a metal pick or small flat blade screwdriver, remove the coolant line on the side of the engine block. Have a 5 gallon drain pan ready to catch any coolant that comes out.
- The starter is anchored to the engine with two E12 torx bolts. Before attempting to remove them, spray both bolts liberally with Blaster PB penetrating oil and allow to soak for 5-10 minutes. You may need to apply the penetrating lubricant several times if the bolts are seized (see next steps). Not pre-soaking the starter mounting bolts with penetrating lubricant could cause the heads to strip during removal.
- Using a long 1/4″ swivel socket wrench with 3/8″ adapter and E12 torx socket, remove the first mounting bolt as shown below. If the bolt is seized, proceed to the next step. If you are able to remove the bolt, proceed to step 8 below.
- If the bolt is seized and won’t break free, spray it again with penetrating lubricant and allow it to soak for a few minutes. Using a ball peen hammer, gently tap on the bolt 10-20 times. Keep repeating this process until the bolt breaks free and can be removed. Be patient…it may take some time. We had to repeat this procedure 6 times before our mounting bolt finally loosened.
- Repeat the above steps on the second mounting bolt.
- When both mounting bolts are removed, grasp the starter and remove it from the engine.
Installing the new starter is a simple process except for one caveat. It is virtually impossible to get a torque wrench on the starter mounting bolts…there is simply not enough clearance to get the wrench in place. This raises the issue of proper torquing of the bolts. As we have always said here at the BMW Repair Guide, sometimes an important procedure within the repair must be changed or adapted to avoid more complicated circumstances. In this instance, “guessing” at the final torque values of our starter mounting bolts presents less of a risk than dropping the transmission so they can be tightened with a torque wrench. In simple terms, make your starter mounting bolts as tight as you can without stripping the heads and you will be fine.
- Install a new starter motor back into the engine. Make sure the mounting holes are properly aligned.
- Install the mounting bolts and tighten as much as possible without stripping the heads. You unfortunately will not be able to get a torque wrench on them. (see our discussion at the beginning of this section).
- Reconnect the engine coolant line. Make sure to put firm pressure on it until it clicks into place.
- Reinstall the two wiring harness leads and torque their nuts to 6 Nm (4.5 ft-lb).
- Reinstall the positive battery and alternator cables. Torque their mounting nut to 12 Nm (9 ft-lb).
- Reinstall the intake manifold following the procedure in our article BMW M52 Intake Manifold Removal – 1995-2000 3,5,7,Z3 Series 6 Cyl.
- Refill the coolant reservoir and check to make sure there is no air in the system. For more information on refilling the coolant system on your BMW E46 3 series, please see the end of our article BMW E46 Water Pump Repair – 1998-2006 3 Series – All Models.