Are you toping up your Coolant?
Thread Starter
Member
Joined: Sep 2007
Posts: 210
Likes: 16
From: Sydney Australia
W205 C250BT & R320cdi-L V251 (sold c220 cdi Elegance)
Are you topping up your Coolant?
Hi,
Interestingly my W205 and W251 have popped up with the Top Up Coolant message this week.
We have seen a few 35°C (95°F) temps here in Sydney Australia the last few days.
My questions are:
1. are you simply topping up your Coolant? Or have you done a coolant flush as part of a major service?
2. Im not expecting this to be the case, but do the diesel mercs require a different coolant?
3. Should i be able to use the same coolant in both vehicles?
Thanks in advance.
Interestingly my W205 and W251 have popped up with the Top Up Coolant message this week.
We have seen a few 35°C (95°F) temps here in Sydney Australia the last few days.
My questions are:
1. are you simply topping up your Coolant? Or have you done a coolant flush as part of a major service?
2. Im not expecting this to be the case, but do the diesel mercs require a different coolant?
3. Should i be able to use the same coolant in both vehicles?
Thanks in advance.
Last edited by GLO; Dec 23, 2021 at 07:19 AM.
Thread Starter
Member
Joined: Sep 2007
Posts: 210
Likes: 16
From: Sydney Australia
W205 C250BT & R320cdi-L V251 (sold c220 cdi Elegance)
My new mechanic says the sensor is located near the top of the coolant overflow, so apparently its triggered when some evaporation has occured.
Supposedly, i can just add de-mineralised water (or cooled boiled water) to bring the level back up.
Supposedly, i can just add de-mineralised water (or cooled boiled water) to bring the level back up.
MBWorld Fanatic!
Joined: May 2021
Posts: 1,317
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From: Plainfield IL
Amg C43
I believe there’s 2 on our vehicles
the overflow is the one closer to the middle of the car
Cap should not be tight on that one.
but don’t overfill
the dealer will do that and it will leak out all over
the overflow is the one closer to the middle of the car
Cap should not be tight on that one.
but don’t overfill
the dealer will do that and it will leak out all over
Senior Member
Joined: Feb 2018
Posts: 333
Likes: 102
2019 CLS450 (C257)
the older W205 had 2 coolant tanks, the 2nd one just over the turbo... while the 2017 and above would have a single coolant tank only.
Likewise the larger CC engines would also have 2 coolant tanks.
For coolant the W205 uses the coolant spec 325.5 (pink in color), part number A000 989 28 25 11.
Hope this helps.
Likewise the larger CC engines would also have 2 coolant tanks.
For coolant the W205 uses the coolant spec 325.5 (pink in color), part number A000 989 28 25 11.
Hope this helps.
Senior Member
Joined: Aug 2019
Posts: 284
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2019 GLC300, 2017 E300
yes, i check and top off frequently even if it's just a splash. I check concentration once a year to make sure it's all good. I replaced the cap recently as the old one was leaking a bit much for my liking when it was venting.. cap replaced and fits much tighter and less of a coolant smell when hot/
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Super Member
Joined: Aug 2003
Posts: 772
Likes: 81
From: Bayarea, California
2003 C320 coupe/c450 in Feb 2016
i got a message that said "Check coolant level"
i looked at the tank, it's really low.
i'm afraid to drive it, is it safe to drive to Mercedes dealer that is like 10 miles away to buy antifreeze/coolant ?
i looked at the tank, it's really low.
i'm afraid to drive it, is it safe to drive to Mercedes dealer that is like 10 miles away to buy antifreeze/coolant ?
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Senior Member
Joined: Feb 2018
Posts: 333
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2019 CLS450 (C257)
you can top up with distilled water (recommended), and in worst case scenario you can even use tap water if you cannot find distilled water.
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Joined: Nov 2016
Posts: 350
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2015 C400
My light came on a few times last fall. C400, slightly over 50,000 miles. After researching the forum, seems like there’s no exact reason why, but the level drops over time. I bought the proper coolant at O’Reilly’s and topped it off. No light since, but this thread is reminding me to go check it.
I think the other coolant tank is a separate system for the turbos? (I could be wrong)
I think the other coolant tank is a separate system for the turbos? (I could be wrong)
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Joined: Feb 2014
Posts: 308
Likes: 20
benzw205
the older W205 had 2 coolant tanks, the 2nd one just over the turbo... while the 2017 and above would have a single coolant tank only.
Likewise the larger CC engines would also have 2 coolant tanks.
For coolant the W205 uses the coolant spec 325.5 (pink in color), part number A000 989 28 25 11.
Hope this helps.
Likewise the larger CC engines would also have 2 coolant tanks.
For coolant the W205 uses the coolant spec 325.5 (pink in color), part number A000 989 28 25 11.
Hope this helps.
Thank you, but can you tell me where are the 2 coolant tanks exactly ?
Senior Member
Joined: Feb 2018
Posts: 333
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2019 CLS450 (C257)
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Joined: Dec 2014
Posts: 480
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From: Waterloo, Ontario Canada
C300 4Matic Tenorite Grey
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Joined: Oct 2019
Posts: 5,151
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From: Colorado
G550
A gallon jug of 50/50 Zerex G40 coolant costs only $20 at most auto stores and is better than diluting your coolant with distlled water or contaminating it with tap water -- would you top off your engine oil with Crisco?. If being down a cup of coolant is worth worrying about, properly topping it off is worth the cost and effort.
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Joined: Feb 2016
Posts: 1,577
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From: Portland, OR
C450, GLC43
Nope
I've only ever had to top off coolant when the seal for the reservoir cap failed and was leaking. Otherwise, never. My C450 is at 128,000 mi since new, is driven spiritedly and kept well maintained.
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Junior Member
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2021 CLA 2.0 AMG W118
Interesting coincidence — seeing that message on both your W205 and W251 at the same time.
Same coolant for both vehicles? Most likely yes, especially if both are using the standard Mercedes-approved coolant (e.g. MB 325.0 / G48 spec). Just make sure you're not mixing different types (like G48 with G40 or Dex-Cool), as that can cause issues.
Also, those high temps definitely can cause a bit more coolant loss through expansion or pressure release, so that could explain the timing. Might be worth a quick inspection for any minor leaks, just in case.
Hope that helps!
Same coolant for both vehicles? Most likely yes, especially if both are using the standard Mercedes-approved coolant (e.g. MB 325.0 / G48 spec). Just make sure you're not mixing different types (like G48 with G40 or Dex-Cool), as that can cause issues.
Also, those high temps definitely can cause a bit more coolant loss through expansion or pressure release, so that could explain the timing. Might be worth a quick inspection for any minor leaks, just in case.
Hope that helps!
Junior Member
Joined: Apr 2025
Posts: 24
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2021 CLA 2.0 AMG W118
MBWorld God!
Joined: Dec 2019
Posts: 32,217
Likes: 6,275
MBWorld God!
Joined: Dec 2019
Posts: 32,217
Likes: 6,275
Interesting coincidence — seeing that message on both your W205 and W251 at the same time.
Same coolant for both vehicles? Most likely yes, especially if both are using the standard Mercedes-approved coolant (e.g. MB 325.0 / G48 spec). Just make sure you're not mixing different types (like G48 with G40 or Dex-Cool), as that can cause issues.
Also, those high temps definitely can cause a bit more coolant loss through expansion or pressure release, so that could explain the timing. Might be worth a quick inspection for any minor leaks, just in case.
Hope that helps!
Same coolant for both vehicles? Most likely yes, especially if both are using the standard Mercedes-approved coolant (e.g. MB 325.0 / G48 spec). Just make sure you're not mixing different types (like G48 with G40 or Dex-Cool), as that can cause issues.
Also, those high temps definitely can cause a bit more coolant loss through expansion or pressure release, so that could explain the timing. Might be worth a quick inspection for any minor leaks, just in case.
Hope that helps!
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From: DFW
SL63
Anytime your coolant is low, your first suspicion should be a leak somewhere in the cooling system.
streborx had a great reply, when he talked about topping off with a 50/50 mixture. In lieu of that, if you find you are topping off on some regular basis, alternate between distilled water one time, and the recommended anti freeze the next.
One reply talked about tap water, and although not ideal, if you are trying to limp to the repair shop, it will do in a pinch, especially if your cooling system is going to get flushed and filled when you get there.
If I had to guess, the most likely cause of a slow leak like you are experiencing, is a water pump seal. Regardless, coolant leaks don’t fix themselves, and generally, eventually get worse.
There are some other interesting(to me) aspects to anti freeze combinations, but I will not bore anyone, unless someone begs me.
streborx had a great reply, when he talked about topping off with a 50/50 mixture. In lieu of that, if you find you are topping off on some regular basis, alternate between distilled water one time, and the recommended anti freeze the next.
One reply talked about tap water, and although not ideal, if you are trying to limp to the repair shop, it will do in a pinch, especially if your cooling system is going to get flushed and filled when you get there.
If I had to guess, the most likely cause of a slow leak like you are experiencing, is a water pump seal. Regardless, coolant leaks don’t fix themselves, and generally, eventually get worse.
There are some other interesting(to me) aspects to anti freeze combinations, but I will not bore anyone, unless someone begs me.
