Two coolant resevoirs?
Thread Starter
Senior Member
Joined: Jul 2019
Posts: 307
Likes: 74
From: New Orleans. LA
amg C63s
Two coolant resevoirs?
I'm new to this forum and a new owner of a 2018 AMG C63s. It appears the car has two coolant resevoirs? Front corner passenger side and also a smaller middle front resevoir? If so why?
Senior Member
Joined: Jul 2010
Posts: 424
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From: Sac, Ca
‘17 GT F1A E85 Monster ‘16 C63s
The coolant tank on the passenger side is for the engine cooling system like every other car uses. The little coolant tank in the center between the turbos is a separate cooling system for the transmission and air/water intercoolers. Make sure both are full when the car is cold.
Senior Member
Joined: Jul 2010
Posts: 424
Likes: 41
From: Sac, Ca
‘17 GT F1A E85 Monster ‘16 C63s
Correct. Separate pumps for each system, however the over flow from the little tank ties into a line for the engines system and can bleed off excess fluid if needed.
Junior Member
Joined: Mar 2019
Posts: 19
Likes: 2
From: Munich, Germany
w205 C63s T-Modell facelift
Man I wish I had seen this thread earlier. There is nothing in the manual about keeping the middle reservoir topped off - I didn’t want to mess with it. Still it will be interesting to find out why mine is bone dry when Mercedes look at my car tomorrow.
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Thread Starter
Senior Member
Joined: Jul 2019
Posts: 307
Likes: 74
From: New Orleans. LA
amg C63s
Is there a fill line when the coolant is cold on either of these resevoirs? The manual makes no mention only something about a marker bar (I've not found) inside the large coolant resevoir. It must reference the C 300 model. Many aspects of the AMG C63s are not mentioned in the owners manual. Too bad Mercedes didn't make a manual supplement for the AMG C63.
Junior Member
Joined: Mar 2019
Posts: 19
Likes: 2
From: Munich, Germany
w205 C63s T-Modell facelift
Replying to my own message in the hope that this might help others. Mods I hope you don't mind the cross post to a couple of threads - this is a potential lifesaver (for the car) so I thought I would try and broadcast it
Keep an eye on that central coolant tank that is in the middle of the engine. If it goes dry you have a problem. This does indeed feed the secondary coolant system for the turbos and gearbox. The pumps are not robust and fail frequently. It's a €250 part so not the end of the world and of course if you have warranty it should be covered.
Your gearbox oil temp will keep going up and there is no warning or shutdown - so check that reservoir every time you check your oil (which is every two weeks, right?).
Keep an eye on that central coolant tank that is in the middle of the engine. If it goes dry you have a problem. This does indeed feed the secondary coolant system for the turbos and gearbox. The pumps are not robust and fail frequently. It's a €250 part so not the end of the world and of course if you have warranty it should be covered.
Your gearbox oil temp will keep going up and there is no warning or shutdown - so check that reservoir every time you check your oil (which is every two weeks, right?).
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Joined: May 2009
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'18 C63A Cabriolet
My auxiliary cooler just took a blow from a pebble or something and a $1700 pin hole was the result. No warranty for "outside influence" failures. Maybe a mesh of some sort is in order here. Anyone protected these highly susceptible parts better than MB did in the design?
And I've looked everywhere in the manual and there's no mention of this second expansion tank. When this tank runs dry, there is no warning or alert. You have to discover it on your own.
And I've looked everywhere in the manual and there's no mention of this second expansion tank. When this tank runs dry, there is no warning or alert. You have to discover it on your own.
Thread Starter
Senior Member
Joined: Jul 2019
Posts: 307
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From: New Orleans. LA
amg C63s
Yes, there is no info in the owner's manual to cover the AMG C63 and C63S. I did not receive an AMG manual supplement when I purchased my car. Is this omission of information for all AMG C63 owners?
Last edited by mstraka; Sep 24, 2020 at 11:09 PM.
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Joined: May 2015
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From: Miami, FL
2003 CL 600
I found them empty quite often, and the system needs to be vacuum filled if it suffers a leak or pump failure (fluid boils out from not moving), so just topping of a reservoir that has been empty for an undetermined amount of time may not be enough.
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Joined: May 2021
Posts: 2
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C63s 2016
[QUOTE=gOt BoOsT;7823054]The coolant tank on the passenger side is for the engine cooling system like every other car uses. The little coolant tank in the center between the turbos is a separate cooling system for the transmission and air/water intercoolers. Make sure both are full when the car is cold.[/
Hi All, I’m new to this first time using wondering if someone can help me.
I have a 2016 C63s coupe and was damaged by a friend who was borrowing it.
It only suffered damaged from passenger wheel, coolant pump passenger side and the coolant rad passenger side and also corner of 2 rads at the front one being the main rad and one at the front which is connected to the passenger small rad. The old pump was broken in half (maybe short too) I have now fitted everything brand new from MB. once fitted I filled up both water tanks one on the driver side and one in the middle of the engine.
the one in the middle of the engine didn’t take much water at all considering it was all empty.
I am now worried that the small electric pump isn’t working how as the water isn’t flowing in the small rad on the passenger side any ideas how I can check if it’s working or when does it work? Also if anybody knows if there is a fuse or relay for it.
thank you very much I would be grateful if someone can help
Hi All, I’m new to this first time using wondering if someone can help me.
I have a 2016 C63s coupe and was damaged by a friend who was borrowing it.
It only suffered damaged from passenger wheel, coolant pump passenger side and the coolant rad passenger side and also corner of 2 rads at the front one being the main rad and one at the front which is connected to the passenger small rad. The old pump was broken in half (maybe short too) I have now fitted everything brand new from MB. once fitted I filled up both water tanks one on the driver side and one in the middle of the engine.
the one in the middle of the engine didn’t take much water at all considering it was all empty.
I am now worried that the small electric pump isn’t working how as the water isn’t flowing in the small rad on the passenger side any ideas how I can check if it’s working or when does it work? Also if anybody knows if there is a fuse or relay for it.
thank you very much I would be grateful if someone can help
Newbie
Joined: Dec 2022
Posts: 12
Likes: 2
From: Lincolnshire, U.K.
2016 C43
When the engine is running, you will see the inlet to this tank go pink as fluid enters the tank. You can’t really see a flow but you can see the presence of coolant.
(if you only have water in there then I’d suggest shining a torch one side and looking the other, not long before getting proper coolant in there!)
I have a small leak on the coolant pipe leading directly from that small tank and so have been looking at this part of the engine for a few days now. By the way does anybody know the part number or name for that exact tube?
(if you only have water in there then I’d suggest shining a torch one side and looking the other, not long before getting proper coolant in there!)
I have a small leak on the coolant pipe leading directly from that small tank and so have been looking at this part of the engine for a few days now. By the way does anybody know the part number or name for that exact tube?
Junior Member
Joined: Aug 2022
Posts: 29
Likes: 5
From: Miami
2019 C63s
I was looking for a thread similar to this as I just had to take in my 2019 C63s. My secondary coolant tank was also empty, and I only found out because I got a warning on my car saying the transmission was overheated and needed to cool before the car was turned off, so I took it in immediately.
Does someone know whether it's normal for this second tank to empty over time.. as far as I thought coolant systems are closed systems and a drying of the reservoir would indicate there is a problem somewhere in the coolant system.
Does someone know whether it's normal for this second tank to empty over time.. as far as I thought coolant systems are closed systems and a drying of the reservoir would indicate there is a problem somewhere in the coolant system.
MBWorld Fanatic!
Joined: Sep 2016
Posts: 1,717
Likes: 608
From: Australia
⏱️ 700HP Facelift converted C63 S Coupe with Drexler 3.06 plated LSD
I was looking for a thread similar to this as I just had to take in my 2019 C63s. My secondary coolant tank was also empty, and I only found out because I got a warning on my car saying the transmission was overheated and needed to cool before the car was turned off, so I took it in immediately.
Does someone know whether it's normal for this second tank to empty over time.. as far as I thought coolant systems are closed systems and a drying of the reservoir would indicate there is a problem somewhere in the coolant system.
Does someone know whether it's normal for this second tank to empty over time.. as far as I thought coolant systems are closed systems and a drying of the reservoir would indicate there is a problem somewhere in the coolant system.
Junior Member
Joined: Aug 2022
Posts: 29
Likes: 5
From: Miami
2019 C63s
Yeah first thing this am I move the car to make my way to work, small coolant leak. Guess I'm taking it back to the dealership again and this time hopefully they actually look at the damn thing instead of charging me a diagnostic fee without finding a problem. I don't understand is this something that wouldn't show up on a pressure test or is some tech in the shop just literally not doing the work they are charging for during the diagnostic?
Newbie
Joined: Jan 2022
Posts: 6
Likes: 1
Mercedes GLC 250d 4Matic
Have a similar problem.
Took the car in for the annual maintanence and dealer showed me the lower coolant reservoir covered in dried/aged pink coolant. He said that the intercooler has an internal crack that significantly increases the pressure in the low coolant reservoir causing it to leak around the cap.
But I’m wondering if maybe the reservoir is just old and the sealing around it isn’t doing the job anymore?
Any feedback is much appreciated!
Took the car in for the annual maintanence and dealer showed me the lower coolant reservoir covered in dried/aged pink coolant. He said that the intercooler has an internal crack that significantly increases the pressure in the low coolant reservoir causing it to leak around the cap.
But I’m wondering if maybe the reservoir is just old and the sealing around it isn’t doing the job anymore?
Any feedback is much appreciated!
Newbie
Joined: Dec 2022
Posts: 12
Likes: 2
From: Lincolnshire, U.K.
2016 C43
I would say he’s talking out of his **** to create work.
There are far too many examples (if you search for it) of coolant caps being replaced and fixing leaks like that.
I would replace the cap, and the reservoir at a push first.
There are far too many examples (if you search for it) of coolant caps being replaced and fixing leaks like that.
I would replace the cap, and the reservoir at a push first.
Newbie
Joined: Jan 2022
Posts: 6
Likes: 1
Mercedes GLC 250d 4Matic
Sure, I guess it’s not completely 100% impossible for the intercooler to have an internal leak through which compressed air enters and increases the pressure in the coolant system, but what would cause such a leak in the first place. Moreover I expect this kind of thing would decrease the car’s power/performance enough that it would be noticeable, right? Especially if the leak would be so pronounced that it causes the coolant to bubble up and out of the reservoir.
MBWorld Fanatic!
Joined: Sep 2016
Posts: 1,717
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From: Australia
⏱️ 700HP Facelift converted C63 S Coupe with Drexler 3.06 plated LSD
@Evo23 @Fishcakes87 @tp767
Are any of you 3 blokes getting a coolant smell as well? From outside of the car after you drive her hard?
Or is it just the empty reservoirs for now?
Are any of you 3 blokes getting a coolant smell as well? From outside of the car after you drive her hard?
Or is it just the empty reservoirs for now?
