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6-Cylinder Starter Replacement
 
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Pelican Technical Article:

6-Cylinder Starter Replacement

Nick Czerula

Time:

3 hours3 hrs

Tab:

$250

Talent:

*****

Tools:

10mm sockets, 10,mm 13mm stubby wrenches, E12, E14 sockets (external Torx), floor jack, jack stands, wheel chocks, safety glasses, torque wrench

Applicable Models:

Mercedes-Benz W211 (2003-09)

Parts Required:

Starter motor

Hot Tip:

Work with a cool engine

Performance Gain:

Reliable and working starter

Complementary Modification:

Replace battery

The starter motor is an electric motor powered by the battery, commanded on when the driver rotates the key to start the engine. The modern Mercedes-Benz starter motor is a permanent magnet direct current electric motor with a solenoid mounted on it. When current from the vehicle battery is applied to the solenoid, the solenoid engages a lever that pushes out the drive pinion on the starter driveshaft and meshes the pinion with the starter ring gear on the flywheel of the engine.

The solenoid closes the high-current contacts for the starter motor. The starter motor then turns the engine. Once the engine starts, a spring in the solenoid assembly pulls the pinion gear away from the ring gear, and the starter motor stops.

On W211 models, the starter solenoid signal is controlled via an integrated relay housed in the driver side SAM control module from the input of the ignition switch. The engine control module grounds the starter relay housed in the SAM module activating the starter. The engine control module receives the start signal via computer data lines. Diagnosing the start signal can be tough, as in some modules it runs through multiple control modules. If your starter motor is good, but lacks the solenoid signal, start by acquiring a wiring diagram for your vehicle and tracing the circuit. Once you are familiar with the layout, check where the signal fails to flow.

When a starter motor fails your engine will not start. You may turn the key and attempt to crank the engine but nothing happens or maybe only a few clicks. It is important to be sure your battery is fully charged and in good condition and that the battery terminals, positive connections and ground cables are tight and corrosion-free before condemning your starter.

Another cause of a no-start condition could be failure of the electronic immobilizer system. If the ignition key does not communicate with the immobilizer or one of the electronic modules responsible for granting access to the starting system fails, you may have a situation, which mimics a failed starter. To test the starter itself, you need to make sure that full battery current is available at the main starter terminal (B+) and that battery current is switched on at the small starter terminal when the ignition switch is engaged. If electrical current is not available at either of those terminals then the no-start condition is caused by an electrical or electronic failure and not necessarily by the starter motor.

The engine starter motor is located on the right side of the engine below the exhaust manifold. It is not the easiest part to access on your Mercedes-Benz W211. To replace the starter, you have to remove the front exhaust pipe.

Remember that your car may have been serviced before and had parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve, as they grow older. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Jack up the front of your vehicle. See our article on jacking up your vehicle.

Remove the engine splash shield. See our tech article on splash shield removing.

Disconnect the negative (-) battery cable. See our tech article on battery replacing.

The engine starter motor (green arrow)is located on right side of the engine below the exhaust manifold.
Figure 1

The engine starter motor (green arrow)is located on right side of the engine below the exhaust manifold. It is not the easiest part to access on your Mercedes-Benz W211. To replace the starter, you have to remove the front exhaust pipe (red arrows). You only have to remove the right side front exhaust pipe. See our tech article on exhaust removing.

Next, working at the center of the vehicle, the center exhaust support has to be removed.
Figure 2

Next, working at the center of the vehicle, the center exhaust support has to be removed. Start by loosening the four 12mm nuts (red arrows). Then remove the two 13mm fasteners (green arrows). Then remove the insulator plate from the vehicle. If you're replacing the driveshaft with the exhaust installed, remove the entire right side support. Just remove the 12mm nuts, then the support.

If you removed the right side front exhaust pipe, the next step is to remove the heat shield.
Figure 3

If you removed the right side front exhaust pipe, the next step is to remove the heat shield. Start by removing the E12 Torx fastener (green arrows). The inset photo shows a better view. There is only one to remove. Then remove the two 10mm heat shield fasteners (red arrows).

Working at the back of the starter, remove the 13mm battery positive (B+) cable nut (green arrow).
Figure 4

Working at the back of the starter, remove the 13mm battery positive (B+) cable nut (green arrow). Then, remove the 10mm nut for the electrical lead (red arrow). The 13mm nut is covered by a plastic cap. Pull this cap straight off to remove it. Leave the cables attached to the starter for now.

Working at the side of the transmission bell housing, detach the battery cable from the holder (green arrow).
Figure 5

Working at the side of the transmission bell housing, detach the battery cable from the holder (green arrow). The green arrow points to the locking tab. Detach the tab. Then lever the holder open (inset) and pull the cable out of the holder. The mount further back (red arrow) is held on with a starter bolt and will be detached in the following steps.

Pull the starter cable straight up and remove it from the holder.
Figure 6

Pull the starter cable straight up and remove it from the holder.

Next, you will remove the starter fasteners (red arrows).
Figure 7

Next, you will remove the starter fasteners (red arrows). The fasteners are E14 external Torx. Use a long extension with a swivel adapter. When you remove the upper fastener, the final cable holder will be removed (inset).

With the bolts removed, detach the electrical connections from the starter solenoid (green arrow).
Figure 8

With the bolts removed, detach the electrical connections from the starter solenoid (green arrow). First pull the large cable off (yellow arrow), then the small starter lead (red arrow).

Now you can remove the starter from the engine.
Figure 9

Now you can remove the starter from the engine. Just pull it out of the engine toward the front of the vehicle. Wiggle it if it is stuck. They usually come right out with no problem. Angle the rear of the starter motor toward the right. Then angle the rear of the starter motor up and remove it from the engine.

Remove the starter motor as shown.
Figure 10

Remove the starter motor as shown. It is a tight fit. Follow the steps mentioned to orientate the motor for removal. Then guide it down, drive end first.

Before installing, I like to place the main starter cable on top of the exhaust flange.
Figure 11

Before installing, I like to place the main starter cable on top of the exhaust flange. This keeps it out of the way. Install the starter into the engine. Install the starter fasteners and tighten.

Install the electrical connections.
Figure 12

Install the electrical connections. Do not over-tighten the battery positive (+) terminal or the starter lead; the studs can break. Use a pry bar to engage the cable mount (red arrow). Press it in and listen for an audible click. Reassemble the exhaust and reconnect the battery. Check the operation of the starter. Then recheck that all the wiring is routed as before.




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