Ours went out on our ML550. Turn key, power comes on the dash, but motor doesn't turn over. How hard is it to replace? Thanks!

 

Don't assume that it is the starter. Remove the starter relay, check to make sure that it is the relay by reading the chart on the cover, and does it look exactly like the photo below?

 

Thanks, I will verify...but assuming that it is the starter (dealer performed diagnostic), how hard is it to replace?

 

Don't believe the dealer. To replace the starter the complete exhaust system must be removed.

 

Please UPDATE YOUR PROFILE in USER CP to include the year and model of the ML.

 

Thanks for the documentation. You don't have to remove the exhaust system. As a hint, you can remove the motor mount on that side and support that side with a block of wood, at least that is what I have read.

 

I didn't find much help in changing the starter on a 2010 550, though I found a lot on the 350, etc., so here is some information for someone else as I have just finished the job. It is basically the same as an ML without the V8, but much harder since you don't have as much room. Don't get frustrated. It is really straight forward, just a pain. I was sore the next day!

The dealer wanted $1,600 parts/labor. I got the starter was $98 shipped from eBay.

It took about 6 hours total, but that was from learning as I go. It would probably take about 4 hours now that I have done it before.
The passenger motor mount needs to come off, period.
Remove the engine cover and pass side intake tube to provide clearance to get to the top of the motor mount bolt.
You will have to have either a 16mm (5/8) short stubby ratchet wrench that is for tight spaces or you will have to grind on the head for clearance. MB also sells a specialized "motor mount removal" wrench that you can get on Amazon. The bolt is torqued pretty good from the factory so you have to use some strength on a 5 " wrench to get it off. And you will be laying across the front of the engine reaching around with your left hand between the inner fender and motor. If you have burly arms, you won't be able to squeeze you arm in there so check before you begin. There is NO other place you can get access to this bolt. The Mercedes specialized tool may help.
You can use metric 12 point sockets on the male torx bolts that are on this vehicle.
You must remove the driver's side 2 lower motor mount bolts so you can lift he motor.
Remove the passenger tire (not required) to allow you to get under the vehicle easier and provide more light.
Remove the starter heat shield and brackets before trying to remove the starter. Remove the 2 starter mounting bolts.
Once the 3 motor mount bolts on the driver's side are removed, jack the motor up with a 4x4 block of wood at the engine bell housing right in front of a cross member support. Put a jackstand with a 2x4 or 2x6 under the transmission pan as backup. It doesn't need to be resting on it but as close as you can get it.
Slide the motor mount out of the front of the motor from the top.
Pull the starter back out of the bell housing and remove the 2 wires from the starter.
Before you install the new starter, bench test it by putting 12 volts to the main stater lug, ground the starter, and get a wire and touch the solenoid with 12 volts. I did this by using jumper cables with one end clamped to the starter and the other end to the neg side of the battery. The positive cables went to the positive side of the battery and the other end to the lug on the starter. Make sure you are holding on to the starter firmly, then get a piece of 8 gauge (or thick wire) wire to the solenoid and jump/cross it to the starter lug. It would suck to install a bad starter (yes, some are bad right off the bat!).
Reverse the order to reinstall.

 

I am not a mechanic but have plenty of tools. It's really not hard if you have a variety of tools. It's really hard, maybe not possible, if you don't have the tools. I didn't remove the muffler or motor mount. Took about 3 hours
Here is what you need
High torque cordless impact wrench. Not the compact/small impact gun that people use for decks
Stubby sockets
Varying length socket extensions and swivel sockets

The key is to remove the two bolts that hold the starter in place with extensions connected to the impact wrench
Unscrew the heat shield from the starter and remove it
slide the starter out and try twisting or pulling out until you find the right angle to fully remove it
Bend the heat shield under the catalytic converter slightly or just enough to slide the starter down

 

So was it the starter?
Is it starting properly?

 

Yup. It starts. Just check the fuses and relays under the hood and the relay in the trunk.