Benzlife240

(2015 C300) So the last three times i have driven the temp gauge has been higher than normal and under acceleration will race into the red. when i decelerate it immediately goes back down to a little higher than normal. The car is 2 years old with 24000 miles and has NEVER been out of normal operating temp and now the last three drives i got this going on. The service manager told me as long as a notice doesn't pop up telling me to stop its ok.

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CJG

Mine has never run above normal. ~90. And I’ve driven hard on occasion.

edgalang

Same here. 90 is normal for me too...regardless how it's driven.

Benzlife240

yeah this just started but the dealer sees nothing wrong with it.

S70Houston

I would seek another dealership, as the one you are commenting on obviously has no clue, nor are they concerned about customer satisfaction.
To me, your issue is definitely NOT normal.

Alfadude

That is definitely not normal. Sounds like you talked about it with the service advisor and they did not actually look at the car. If so, the car is under warranty. Just make an appointment to bring it in and have them find out and fix the issue. And if that dealer will not look at it, as someone else said, go to another dealer.

Benzlife240

They had the car for three days AND I had given them a video of it occurring. Still said “normal vehicle operation.”

Alfadude

Incredible. I find that hard to believe. Did you ask the why that is considered normal operation? I have never heard of something like that as being normal on any car. Or did they say they could not duplicate the issue and that is why they said 'normal operation"?

Benzlife240

When I picked it up and they told me it was normal AND they couldn’t get it to do it again I told her it would happen on the way home. It did so I called and she again told me as long as a window didn’t pop up saying stop, I was good. I went off. Explaining the color red was universal for stop or bad. That common sense would dictate that if after owning it for three years and all of a sudden it started doing it everyday something had changed and for the worse. She kept reciting bull**** without using her brain. She discontinued the conversation and said someone would call me Monday. I told her to have someone call who knew something about cars.

keith100

Something is definitely not right if the temp moves into the red. That's why its coloured red.

Either a sensor is broken, leaving you without protection if something goes wrong later, or the motor is overheating.

I'm amazed the service advisor suggested you drive till it breaks.

You don't say where you live, but if possible I would change dealer.

Good luck

S70Houston

No disrespect towards women, but maybe “SHE” needs to be replaced with a “HE”, or at least get some proper training from MB!
My wife definitely knows more about cars than the “SHE” service advisor at your dealership.

FIND ANOTHER DEALER!!!!!!!!

Moto_Guzzi

It seems some people are borned without the ability to understand a complaint regarding "intermittand" conditions/failures/warnings, and couple to that faulty test equipment/operation etc, and you get a handfull of "normal/it's ok". I always wondered about the engineers thoughts reading some stuff about his creation, although he may not speak, his thoughts maybe priceless.

dol4er

My car has never passed the 90 degrees Celsius mark and I definitely think it is not normal to overheat so you must find what is wrong and fix it.

c300white

yep - red zone could be a number of things - and could damage the heads : head gasket if you let it run up there .

Does it overheat in traffic ? At speed ? How hot is it outside when it goes red ? Does heater work at full temp ? Is ac on or off when it does it ? Is coolant level correct at cold ?

sticking thermostat is most likely cause. I’d try bleeding the system to see if any air is in there first and Check if fan is working. Is there debris like leaves in front of radiator / blocking it ? If none of that - could be faulty sensor.

Find another dealer and write to mb-USA about your experience with first delaer ....

Colin G

I'd wager it is a thermostat issue and it needs replacing.

Adi-Benz

This would be my guess as well. Usually when its broken though, it fail-safes and stays open. I wonder what could be wrong.

CJG

Correct. They typically fail open and the motor won’t heat up properly.

Adi-Benz

Yes, but the OP is having the opposite issue. My thermostat failed but it was about 80* consistent.

CJG

Exactly. It was suggested it might be a thermostat. It may, but they typically fail the other way.

Adi-Benz

Ah, I suppose I read it incorrectly, my fault if I came out as rude.

Benzlife240

So Sunday I drove to the airport in DC about 35 miles. It was in the red for about twenty minutes of the ride. Pretty much any speed above around 65mph. I took yet another video for documentation.

Monday came and by 2pm I hadn’t received that promised phone call. Pissed off, I called. I called repeatedly! Sometimes no answer sometimes redirected to a voicemail and sometimes redirected to some scheduling personnel not related to my dealership specifically. Finally I selected the option for a sales rep at my dealership, knowing salesman are hungry for business and someone would snap the call up. I was right. I explained the history and my 30 minutes so far trying to speak to someone. He hand delivered my info to a service coordinator named Milton (chantilly Virginia Mercedes). Milton was the first service member who said, “in the red?! That’s not good!” He set up an appointment for this morning, Tuesday, then hand selected a loaner car for me exactly like mine. I was feeling a little better.

Then last night on the on the way home from the airport of course the temp was in the red again except this time about 5 miles from my house it escalated to the red screen “PULL OVER IMMEDIATELY AND SHUT THE ENGINE OFF.” So I found myself on the side of the expressway at 1030 last night. Lovely. I sat for a half an hour then put it in eco-mode and limped it home on back roads at 35 mph.

Bright and early this morning I limped it all the way over to the dealership on back roads in eco-mode at low speed. Milton wasn’t there that early so I spoke with another agent. I explained the history. She said she truly had no excuse to give for what had taken place. She also informed me the female service manager I had problems with was on her last week at the dealership. I was then given my loaner, nicer than usual model and off I went. I’m iverseas for a couple days then hopefully it will be fixed whatever the cause by next week, considering there is a holiday this week.

Ill keep everyone updated. Thanks for ALL the input so far.

T.

ItalianJoe1

Glad they are actually handling it now. There's no reason for the car to be in the red, and driving it until it breaks is neither safe for you nor wise for the dealership.

Thermostat problems aren't uncommon but affect the CLA more than the C class, in my experience. These cars have an electronically controlled thermostat, and odds are the little vacuum actuator that actually moves the t-stat valve is stuck, not allowing it to open properly. That's why it can cool at low speeds/loads, but not once you start to go faster. The piece is plastic and they are known to get bent and stuck.

Benzlife240

I got a call last night from the dealer. They are replacing the thermostat and the water pump. I asked if they thought all that driving in the red caused any engine damage. I was told it would be very unlikely.

We shall see.

ItalianJoe1

You should be fine. The warning that popped up to stop engine is at a point before you start doing any heat related damage, driving with it hotter than usual, but not with the overheat warning, shouldn't have any adverse effects.