E55 won't start
 

So my parents had reported this problem once before, but I have never seen it. We just stopped at a rest stop, and when I went to start the car back up, it refuses to crank. It shows all of the warning lights on the dash on when you try to start the car, there is a slight buzzing noise for a moment after you turn the key, but then nothing happens. In my parents case, it just started after waiting a few minutes. Not sure what will happen this time.

Anyone heard of this issue and know the cause?

I should mention, the problem surfaced immediately after replacing the secondary coolant pump, and the engine has felt more coarse than normal today. Almost like the engine mounts are going out.

You replaced CPS?

Would need to know what that is to answer

Crank shaft position sensor, common problem on these cars.

Okay, no I have not replaced that. The car did start right up again after about 15 minutes. Oddly, both days this happened involved driving from relatively high altitude down to lower altitude. First time parents were coming back from Switzerland to Central Germany, and today we went to the Eagles nest and then drove to Munich.

I will have to look up the Crank Position Sensor.

Your symptoms are definitely pointing at CPS

"it refuses to crank" (starter turns the motor or not?) "there is a slight buzzing noise for a moment after you turn the key, but then nothing happens" turning the key and starter does not engage??
Just did the CPS on the m112 (C320); Symptoms of CPS are car dies when it gets hot, then the the starter will spin the motor, but it won't start. Then after a cool down period the motor will start. (expansion from heat causes the a break in the signal from the CPS. Then when it cools, contact is made again....the signal is sent and the car starts.

A no crank situation is not solely a bad CPS. You need to pull some codes.

Need to know..... year and mileage

It is a no crank situation. Starter does not engage at all. Turning the key yields nothing at all except a light hum, which happens when the "run" position is reached, but quickly stops. Would guess it is fuel pump priming or something along those lines.

The car is an 06 E55 Wagon with 118,000 km.

CPS should be as preventative maintenance. I'm on my out the door, so I got to keep it short. Search no crank. Could be grounding strap, fuse, selonoid or starter it's self. Any CEL's?? (check engine light) Pull codes.

Check the starter relay as well. Check for corrosion too.

No codes. I have a Bluetooth code reader and torque but I'm not seeing anything.

Check for voltage to the starter solenoid....or jump the solenoid to bypass the ignition and see if she cranks. If it does not crank, you may have a failing starter.

It does crank after 15 minutes or so. Starter seems fine. Just won't even attempt to crank for a while when the issue happens.

Your problem is not even related to the CPS, so ignore that. Battery voltage, and cables? Go into UB Volt measuring mode, and check. Are you using a Key (EIS), or keyless go on the shifter?

Look at this, ( even though not exactly the same as your problem). https://mbworld.org/forums/w211-amg/...ont-crank.html

Since the starter works by jumping it (as suggested by SICAMG), what is the voltage at the solenoid?

Don't need to jump anything. Just wait 15 minutes and it starts entirely normally. Haven't had the opportunity to check things but should be able to tomorrow. Car is currently parked in an underground garage in Munich and a bit hard to get to. Not to mention have other things on my mind at the moment, such as the giant schweinhaxe in front of my face at the moment.

Will report voltages tomorrow with a little luck.

Enjoy your meal.... My guess is your starter or solenoid is on it's way out......starts fine....... heats up.....won't crank.....cools down...starts fine:popcorn:
Trouble shoot it when it's acting up. Forgot to say... next time it won't start, smack the starter with a hammer. You can get at it from the top of engine bay with a piece of pipe. If it works with the smack, it's on it's way out.

Voltages were 12.3 with the vehicle off, and a stable 14.1 after the idle settles on startup. Car has been starting normally again for the last 2 days since the most recent incident.

What is the voltage under load? What happens to the voltage when you try to start the car? Have you looked at the fuses, relay, solenoid connections?

Your starter died. Same exact thing happened to me. Beat on it with a hammer until you hear it crank for a second to diagnosis. CPS is crank no start. No crank on these cars if the immobilizer is disabled during ignition startup = dying starter. Rockauto has the improved one from Bosch cheap. Sounds like a spaceship when it turns. Absolutely amazing.

P.S. - I skipped ahead after the first 3 posts. Replace it when convenient, because it will happen again eventually.

Not sure exactly what you mean by under load. If you mean when you run the engine hard, it appears to top out at around 14.3 volts, and otherwise stays steady at 14.1-14.2 volts while the engine is running with the exception of an occasional blip down into the 13s which seems to be tied to the transmission shifting gears on deceleration, but doesn't always register, possibly due to timing etc. On startup, the voltage drops to somewhere in the 11s, but it starts so fast it's difficult to be more precise.

Can you explain how it's a dead starter when it works perfectly fine 98% of the time? Just curious.

Solenoid starts to go, or armature starts to fail. I noticed that my car would crank, hesitate for a half crank, continue to crank but ultimately not start. That was the beginning symptoms of the starter failing. Then eventually, it just died without warning, and wouldn't start.

You get all kind of weird symptoms of a bad starter. Short version: If you turned the key, and it didn't crank, it's either your battery or the starter. If it's the original starter, consider replacing it. If you want to verify the diagnosis then the next time it does it, hit it with a hammer. It'll crank, or turn over a few turns after you do and you'll know for sure.

Where is the starter motor located on these cars, and would I be able to hit it with a hammer with the car on the ground?

Passenger side, look for the furthest spark plug in the rear and go straight down.

In your case it sounds like the solenoid, so tap on that first.

E55 not cranking!!
 

Well replaced my battery, still didn't start, turn key on hear fan or blower comes on and esp light dash!! think I should try CPS? was starting fine month ago!
Thx 👍