I have 2014 c63 with about 72k miles the car has been great with no problems until yesterday when I was at a stop it started to rough idle and shake a bit and that’s when the check engine light started flashing and then stayed on solid. I drove the car a few miles back home, turned it off waited a few minutes to turn it back on and same thing happened. I then disconnected the negative side of the battery and connected it 10 minutes later, I go to start it and when I try to start the car it makes almost like a vacuum noise but does not start. Does anyone know what can be the issue? Any help would be appreciated

It could be number of things. I’d start with checking the codes and going from there.

Does the engine crank, is there spark? When you turn to the key to start position, what exactly happens? Do you hear anything else, like clicking noise from engine compartment?

It could be fuel delivery related as well, like a clogged fuel filter. It could also be as simple as dead battery, alternator or even the starter. List can get pretty long if we’re just guessing. Get the codes read.

thank you for your reply, I’m on my way to get a scanner now but when I turn the key the lights on the dash light up so it’s probably not battery but it does not crank at all, I just hear a vacuum sound

The car can have enough power to light the dash lights but not enough to start the car. When the battery voltage falls below a certain level the starting circuit is disconnected by the ECU or some other computer control and the car will not even turn over. The first thing is to check the battery voltage and if it is below 11.5 volts or so (not sure of the exact voltage it cuts off at) then it is probably best to fully charge it with a smart charger (like a CTEK). This may save your battery if it is discharged and get you going again. It happened to me once and has never recurred and the battery in my 2012 is original.

If the vacuum sound is very loud then it is probably the cooling fan on full and you likely have another issue of some sort.

i was able to get the car on a lift and remove the starter, I was definitely not expecting to find this

Nothing a little JB Weld won't fix.

Oh Oh, must have been the starter whirring and not engaging. Better check the gear teeth on the flex plate and the flex plate itself as well.

That is a new one I have not seen that reported on a c63. Has it ever been out and or replaced almost like it was loose or something else is in there loose and hit it

I'm going to go out on a limb here and say that broken starter is a symptom of the larger issue. Not the cause.

+1
Perhaps an injector was stuck open and during the next engine turnover the starter broke due to hydrolock.

I think you may be right im trying to turn the engine over by hand and it gets stuck at a point and when I go the other way it gets stuck again. What are my options now? I’m not too knowledgeable on these motors

Do I remove the plugs and see if it will go by hand?

From what I've seen is you start by removing all 8 spark plugs, and then turn the engine by hand.
If its turning freely crank the engine with the spark plugs OUT, after you disconnect the fuel pump (or remove its fuse) to remove the fuel from the cylinders.
If in fact fuel flooded the engine, replace all fuel injectors, spark plugs, change the oil, and pray that a rod wasn't bent. Plenty of M156 engines hydrolocked and survived without any issues. These are robust engines.

I gathered this info from similar incidents. I am NOT an expert by any means so do search before proceeding forward

Good luck

i tried to turn it with a ratchet and a bar with more force and it was able to turn and there is fuel coming out of the exhaust where I took it out to replace the starter

So here’s where I’m at now:

my initial problem started when I was sitting at a light and the CEL started flashing and stayed on and the car started to rough idle. Driving it home it would be shaky accelerating and going up hills. I hooked it up to a scanner and it told me cylinder 8 was misfiring. I reset the codes and took it for a short drive and realized smoke was coming from exhaust. I shut it off for a while and when I go to start it there is a whirring sound so I took out the starter and replaced it with a new one. Now when I go to start the car the engine actually cranks but won’t fire up. I’m really stuck at this point and thinking about bringing it to the dealer. What could be the reason it won’t fire up now?

Flashing CEL means stop the car right fkn now and call a tow truck. Continually driving with a misfire or other condition that causes a flashing CEL will likely damage the motor.

it started flashing and then stayed solid

So along with the new starter I ended up putting in new injectors spark plugs and air filters and i went to start the car and it’s still idling very rough and the codes are still showing cylinder 8. Is this a sign the rod is bent, what are some tests I can do to confirm it?