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Discussion Starter · #1 ·
Thanks to the admins for putting this forum together. I've had periodic low coolant warnings since purchasing my EQV new last year.

After the first two drops the dealer topped it up and said it's fine. After the 3rd and most significant drop (half the reservoir gone and a main battery warning light came on), I insisted it got towed and properly inspected. Dealer says no sign of leakage and pressure test is fine so everything's fine. Everything definitely isn't fine - coolant might be leaking into drivetrain and/battery. I don't want to come to a stop on a busy road with regen braking limiting my options to coast to safety.

I raised it with Mercedes UK, they reviewed the case and said everything is fine. I'm about to get a lawyer involved as a last resort. I would like the fault properly investigated to rule out coolant in the battery or motor.

I note lots of stories with coolant warnings on the main EQ forums, including what appears to be a fleet wide recall in China for the same/a similar issue. Has anyone had this experience with their EQV?


Sport Premium
23k miles driven
Get 190 miles in -4 (cabin heating max 15C, rear heat off, heated seats on, hats on!)
Get 220 miles in summer
Note I've removed all but one of the rear seats so weight greatly reduced
Apart from this issue the vehicle has been incredible - a real game changer for an eco-nut windsurfer
 

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Not EQV but after 15mths my EQC has thrown this up, the level is where it should be at the marker just, for a variety of reasons I have not been able to get any Mercedes’ antifreeze so so far have not topped the car up but the message is not there all the time and disappears as it is used and or warms up from a rise in the ambient temperatures. It reappears in really cold weather leaving me thinking the liquid reduces in volume in the cold, but once I top it up I can see if it reappears.
I am begininng to think there might be an issue with the coolant evaporating during the charge process hence it needs topping up, indeed topping up the antifreeze is a normal thing to do with ICE cars albeit I never had too possibly because it stayed above the min mark and was topped up at the annual service.
Outside of China there seems to be no history of leaks into the motor as far as I am aware though that story has made a lot of us very wary when we get the message. I also think they do not put a lot of liquid in the system, the fill level marker is very low, maybe it is simply a matter there needs to be more liquid to start with? The system is more complex or different than in an engine I suspect and possibly Mercedes’ are learning the hard way their design, either with quantity of liquid or sensitivity of the levels is not correct. However if Mercedes’ are happy I would accept it, keep a container handy and top it up when the car says it wants a top up. Just a check was it an EQ approved Mercedes’ garage who checked the system? My ordinary garage who sold the car would not service it as they are not Mercedes’ EQ approved.
 

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Discussion Starter · #3 ·
Thanks for the thoughts. Brief summary of my last conversation with the service manager.

Me: Can you investigate further before I take the vehicle back?

Service manager: there's nothing to investigate because our tests show it's not losing coolant

Me: wuh? You know it arrived on a flatbed trailer on the advice of your recovery team because of the large coolant drop and main battery warning light?

Service manager: there's nothing to investigate because our tests show it's not losing coolant

Me: have you looked at the document I sent detailing the amount it had dropped as well as the previous drops last year?

Service manager: (becomes aggressive, implies I'm making it up)

So I'm reluctantly going the legal path, have spoken to lawyer. Super annoyed. I paid £70K for this vehicle 18 months ago. They are basically telling me to get lost unless I come to complete halt on the road.
 

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So. Different scenario to me then if you have already sufferred a severe drop? What was the circs of that?
The first time I checked the levels in the tank on the left which is the one you check the level in according to my EQC manual it just covered the T marker at the bottom ie at the level it should be apparently. This am before using the car I went out and checked it and the level was to the top of the tank and the one on the right also had liquid as it always has had about half full. I got the message only on the drivers screen not on the central screen ( I have seen a message there before in basic script like DOS in windows which inc the message go to the garage) but it did not register in the maintenance messages. The liquid was warm not hot but warmer than ambient (it was around -2.5C). Went out did some short journeys and the left tank stayed at the same level. The car has been on charge today and the level was the same after a few hours the left tank was no longer above but was at ambient temperature the right was warm so liquid is clearly circulating around as the battery was charging (from 18 to 60% so the lower end of the range), and indeed I have often heard it trickling back into the right side tank at all sorts of times and scenarios.
I am now left wondering where is the sensor that says the liquid is low as the tank I am required to fill looked full? Perplexing but it does not sound quite the same as your issues.
I really do not want to go back to my garage if I can resolve the issue by just putting some liquid in as it is a 200km 2.5hr round trip so a pain in the proverbial as it is to get MB antifreeze is an hours round trip. I will drop them a line and see what they say but I expect the usual bring it in for us to look at it response which is not that simple!
 

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Discussion Starter · #5 ·
Yes my issue is longstanding and each time accompanied by a low coolant warning on the dash. Picture is of the last drop which my dealer is saying shows no evidence of a coolant leak. It's like the monty python dead parrot sketch.
Vehicle Automotive lighting Motor vehicle Bumper Hood
 

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Do you have 2 coolant tanks? The EQC has one on the left with dark coloured plastic topping it and which is shown asthe tank you refill, and one on the right like the one in your photo.the level looks similar and I have always assumed it was an expansion tank and as I said above you hear the water trickling into it. The level is variable from my experience. It was the left tank which was low when I received the first message and which has been much higher today, the right tank looked more how it always looks as above. I willhave a look at it tomorrow and see if there are any level indicators in it but the manualclearly shows the left as the one you top up but that iswhere theyare generally located in mercedes cars whatever the engine.
 

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Discussion Starter · #7 ·
Yes two coolant expansion tanks - only the left one has been dropping. I don't know if it's the battery, motor, or cabin heat system. Dealership are giving zero information, but I've just found this in the manual:

"Regularly check the drive cooling system and the heating system for leaks. If there is a loss of coolant, have the cause determined and rectified in a qualified specialist workshop without delay."
 

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Just been and taken the lid off the left tank before I pre heat the car and it the level is just on the marker though from the side the tank looks full. The right probably looks like the one in your photo and that does seem avaiable level. They are both expansion tanks so levels will rise and fall depending on the temps of the liquid. Temps are slightly warmer though still below freezing.
I shall buy some merc fluid and top it up ( that will involve and hour round trip🙄) but also send a note to my EQ repairer and see what they have to say. Will update.
 

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Ok went to my supplying dealer today and bought the required liquid and they topped up seemingly thinking to have such an error message in cold weather was quite normal. The error messages which hung around yesterday during some very short and very cold journeys had all cleared by this am and it did not pop up again I assume because it was 10deg warmer!
The service receptionist put in about 350ml and he said he topped up both containers. I have not checked it yet leaving it until tomorrow am so it is like for like conditions. I will then monitor. However the service receptionist (who I know has worked in the workshop as I am a longstanding customer of this garage going back to 2011) said it is not unusual in cold weather as the liquid reduces in volume. So I now need to monitor to see if I continue to loose liquid or not. I will keep you updated.
 

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Yes two coolant expansion tanks - only the left one has been dropping. I don't know if it's the battery, motor, or cabin heat system. Dealership are giving zero information, but I've just found this in the manual:

"Regularly check the drive cooling system and the heating system for leaks. If there is a loss of coolant, have the cause determined and rectified in a qualified specialist workshop without delay."
From forum discussions on the ICE equivilant I think the left will be the main ie engine or battery the right is for other elements.
 

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Upddate checked the car today and there has been no drop in the coolant level it looks the same as in the photos. The car has been used for a few short journeys only and the temps have been mild. Fingers crossed it was just evaporation over a period As opposed to an actual leak.
 
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