Overheating?
Visual inspection of the coolant level looked OK, they topped it off, no codes show up in tests, no leaks nothing.
2 days later, I am on a freeway, and doing 60-65, all is fine. Go into left lane to overtake a car, and go into 70-75, and the temp goes hot again, AND this time also shows the Coolant Hot, Please Shut down the Engine warning, and within 10sec or less, I am on the shoulder, engine off.
Towed to the dealership, so far nothing looks wrong, car will be there to troubleshoot and a possible ride on the freeway again by the techs. Again, coolant is topped off, no codes etc show up in diagnostics.
EDIT: No obvious overheat smell or anything in/around the car when on shoulder or driving.
Thoughts?
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I assume, its something that is not activating at right time leading to the warning.
I assume, its something that is not activating at right time leading to the warning.
But, the tech was able to reproduce the scenario on freeway and the coolant pump control level is now found to be stuck and not operating. Waiting for time to fix etc.
Thanks!
The coolant gauge sits at about "7" or "8" of those progress boxes in the gauge. Not sure if that is the normal operating temperature for C300s.




The coolant gauge sits at about "7" or "8" of those progress boxes in the gauge. Not sure if that is the normal operating temperature for C300s.
That's where mine sits.
Yesterday, I had to drop off my C400 for a sunroof repair (little piece of plastic broke, entire assembly needs to be replaced... ) and they gave me a C300 loaner - brand new 2017 w/very few miles on it.
I get home, change, leave and head towards the park for my evening walk. Car gets 10 minutes from home and overheats. Like, boiling coolant spraying over the ground. Nasty overheating situation.
I let it cool down, limp it back to the dealer (only a few miles away), and get yet another 2017 C300 as a consolation prize.
So that's my experience with overheating. I have put 43k miles on a C400 over the last 2.5 years - never seen the temp gauge move past the first tick right of 80. And it is running the DINAN piggyback in Race mode.
@l3it3r
Just to let you know. I already replaced my sunroof twice. Once, the sunroof got stuck while being operated and the sunroof was left open permanently. Luckily it was not raining. The next time the screen (that thin piece of cloth) sagged and the sunroof got stuck again. This time it was permanently closed for a change.

For the past 1 month, I have had irritating rattles from the sunroof fixture. I am sure they will have to remove it and assemble it again to fix that. God save me after I run out of warranty.
Last edited by Unnimon; Jul 25, 2017 at 04:31 PM.
Yesterday, I had to drop off my C400 for a sunroof repair (little piece of plastic broke, entire assembly needs to be replaced... ) and they gave me a C300 loaner - brand new 2017 w/very few miles on it.
I get home, change, leave and head towards the park for my evening walk. Car gets 10 minutes from home and overheats. Like, boiling coolant spraying over the ground. Nasty overheating situation.
I let it cool down, limp it back to the dealer (only a few miles away), and get yet another 2017 C300 as a consolation prize.
So that's my experience with overheating. I have put 43k miles on a C400 over the last 2.5 years - never seen the temp gauge move past the first tick right of 80. And it is running the DINAN piggyback in Race mode.

For the past 1 month, I have had irritating rattles from the sunroof fixture. I am sure they will have to remove it and assemble it again to fix that. God save me after I run out of warranty.
If the car rattles any more than I've had to deal with (5-6 times in the service bay for rattles) after this, I'm definitely moving on. That Porsche has been calling my name anyway
Here's the issue with that argument: In order to throw a code, the manufacturer had to have the forethought to anticipate that specific measurement, combination of measurements or issue as being out of spec and program the car to respond by doing XX or YY. There's NO possible way MB could predict every single thing that could go wrong with the car.
That being said [or typed], if they said there's no codes, I would change to a different dealer. There HAS to be a coolant warning or an overheat warning stored that would generate a code. Anything that appears in the instrument panel is also stored as either a temp fault or a permanent fault.
Personally, I don't like getting 1/2 the story from the dealer, but i would push this.
Hopefully you have pictures or a video of the issue from the display.... I ALWAYS take an immediate picture of any "warnings" from the car so the dealer can't respond with "there's nothing wrong"....





