Coolant use?
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From: Maryland
2024 S580
Coolant use?
My 2020 S560 has 27,000 miles on it, twice now I have gotten a low coolant warning on startup and needed to add coolant. Has anybody else experienced this? I have never had a car I had to continually add coolant to like that...
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From: Fort Worth TX
2020 S560, 2014 SLK55 (Prev. 2016 S65, 2013 SLK350, 2008 CLS63, 2006 E350, 2006 CLS500, 2005 C230K)
You likely do have something to look into with that consumption. It could be something simple like a pinhole in a hose or something more complicated.
Would advise to inspect all hoses and water pump for signs of dried up coolant as a next step. Also check reservoir for signs of contamination.
If nothing found an oil analysis at next oil change.
Would advise to inspect all hoses and water pump for signs of dried up coolant as a next step. Also check reservoir for signs of contamination.
If nothing found an oil analysis at next oil change.
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S600
The pressure cap is a place where coolant can leak (in vapor form) without leaving traces--the water leaks out but the glycol does not.
I had an incessant leak in my Ferrari until they fingered the cap.
If the rubber seal does not look abso-friggen-lutely perfect; suspect the cap.
I had an incessant leak in my Ferrari until they fingered the cap.
If the rubber seal does not look abso-friggen-lutely perfect; suspect the cap.
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From: Charlotte NC area
2019 WS222 S450 4-Matic / 2007 W211 E350 4Matic (Sold) / 2008 X164 GL320 CDI
You need to add UV tracer dye to the system, and find the leak.
Also get an oil analysis in case it is internal.
Dealers will just start swapping parts and are just as likely to cause more problems later.
Also get an oil analysis in case it is internal.
Dealers will just start swapping parts and are just as likely to cause more problems later.
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From: New Orleans Area
2015 E400 Sedan
closed system which means should not loose coolant:
So have the system pressure tested to see if there is a leak and where it is located.
And have cap tested which is all Standard diagnosis of coolant leak.
In mean time check oil for chocolate mousse looking stuff in engine oil fill cap which is sign of possible head gasket issue or at worse a cracked block.
So have the system pressure tested to see if there is a leak and where it is located.
And have cap tested which is all Standard diagnosis of coolant leak.
In mean time check oil for chocolate mousse looking stuff in engine oil fill cap which is sign of possible head gasket issue or at worse a cracked block.
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From: pittsburgh
'25 740i; '15 targa4s; '24 cayenne
i had to top off my 2020 560 last winter. dealer said just put some water in. lol. i did! it worked fine. this summer, i took the car in for its annual maintenance, they found a cracked coolant reservoir and replaced it. when i asked them why i didn't see any evidence of a leak on the garage floor, they said there is a pan under that section of the reservoir to catch drips. musta been a slow drip! anyway - yes it happens. it is an easy fix. mine was under warranty.
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2019 S560, 2015 Honda Civic Hybrid
Interesting ... I had my coolant light come on after first year of ownership and topped it off with about 8 oz of distilled water. My Indy did a pressure check and found no leaks, so I'm just going to keep an eye on it.
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From: Maryland
2024 S580
Definitely nothing in the oil filler cap...one of those times I'd like to have a dipstick to see the oil. I'm going to add distilled water, I'm about 2,000 miles from the 30K A service and I will bring it to their attention then. The dealer filled it around 10k miles and they didnt seem concerned that it was low at all.
I only get the low warning in the morning at the first startup, then I don't get it again.
I only get the low warning in the morning at the first startup, then I don't get it again.
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Joined: May 2011
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From: Fort Worth TX
2020 S560, 2014 SLK55 (Prev. 2016 S65, 2013 SLK350, 2008 CLS63, 2006 E350, 2006 CLS500, 2005 C230K)
A single fill after being placed in service is normal as the fill from factory could have had an air gap. But OP continued need to add is a problem.
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From: Palm Beach, Fl
2016 S550 sport, 2018 GLC300, M3, Zo7, 2021 Sierra Denali
As Tom said above, once 2 years ago I had to add a couple of ounces of coolant. I had same concern, where did it go? I have seen some say they had leakage at a joint in some hoses . Easy fix. But not my issue. I have a lift in my garage, and give a good inspection with led lights everywhere, and have never found any seepage from anything in 46,000 miles. So me adding was 17,000 miles / 2 yrs ago, nothing since. I'd have it checked, but wouldnt be too concerned.
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From: Charlotte NC area
2019 WS222 S450 4-Matic / 2007 W211 E350 4Matic (Sold) / 2008 X164 GL320 CDI
As Tom said above, once 2 years ago I had to add a couple of ounces of coolant. I had same concern, where did it go? I have seen some say they had leakage at a joint in some hoses . Easy fix. But not my issue. I have a lift in my garage, and give a good inspection with led lights everywhere, and have never found any seepage from anything in 46,000 miles. So me adding was 17,000 miles / 2 yrs ago, nothing since. I'd have it checked, but wouldnt be too concerned.
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From: Florida
2013 ML350, 2019 S560
The pressure cap is a place where coolant can leak (in vapor form) without leaving traces--the water leaks out but the glycol does not.
I had an incessant leak in my Ferrari until they fingered the cap.
If the rubber seal does not look abso-friggen-lutely perfect; suspect the cap.
I had an incessant leak in my Ferrari until they fingered the cap.
If the rubber seal does not look abso-friggen-lutely perfect; suspect the cap.
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Joined: Aug 2017
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2019 S560, 2015 Honda Civic Hybrid
Oh yes, the telltale white residue, that's definitely coolant. Oh, and btw, one of reasons I took off those useless covers to be able to keep an eye on things like this.
BTW, didn't mention in my reply earlier but when I first got my car in 2021 it had a bad cap with white residue underneath and needed coolant. I bought a $6 replacement on Amazon and no more white residue, but could still be losing a little bit of vapor here and there. Does seem to be a bit of a weak link in the cooling system
BTW, didn't mention in my reply earlier but when I first got my car in 2021 it had a bad cap with white residue underneath and needed coolant. I bought a $6 replacement on Amazon and no more white residue, but could still be losing a little bit of vapor here and there. Does seem to be a bit of a weak link in the cooling system
Last edited by Tom in Austin; Sep 17, 2022 at 12:04 PM.
Senior Member
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Posts: 497
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From: Palm Beach, Fl
2016 S550 sport, 2018 GLC300, M3, Zo7, 2021 Sierra Denali
I'd say you saved yourself a dealer visit! Clean that up and put a new MB cap on, and I bet your good. I'd inspect weekly for a while. Looking at the dealer parking lot and service drop off gives me anxiety about getting a ding or scratch. I avoid the dealer at all cost! Good find, thanks for posting!
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From: Lower Alabama
2000 E320 Original Owner 2007 CLK550 Cabriolet 2015 S600
Glad you figured out the problem. My problem is I get a low coolant message every time I start the car but the coolant level is fine when I check it.
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From: Maryland
2024 S580
Originally Posted by homepukes;[url=tel:8636539
8636539[/url]]Glad you figured out the problem. My problem is I get a low coolant message every time I start the car but the coolant level is fine when I check it.
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From: New Orleans Area
2015 E400 Sedan
remember caps are the RELIEF VALVE of the coolant system.
They are what limit the pressure build up in the system so yes they can vent sometimes.
Pressure in system is important to increase coolant boiling pointkeep boiling point lower but too much can cause other leaks.
They are what limit the pressure build up in the system so yes they can vent sometimes.
Pressure in system is important to increase coolant boiling point
Last edited by ygmn; Sep 19, 2022 at 06:42 AM.
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SL500 R230
Definitely nothing in the oil filler cap...one of those times I'd like to have a dipstick to see the oil. I'm going to add distilled water, I'm about 2,000 miles from the 30K A service and I will bring it to their attention then. The dealer filled it around 10k miles and they didnt seem concerned that it was low at all.
I only get the low warning in the morning at the first startup, then I don't get it again.
I only get the low warning in the morning at the first startup, then I don't get it again.
Out Of Control!!
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From: Charlotte NC area
2019 WS222 S450 4-Matic / 2007 W211 E350 4Matic (Sold) / 2008 X164 GL320 CDI
The mayonnaise in the oil filler cap being caused by a failure in the cooling system is largely an urban myth.It can happen but normally It's caused by using the car on short trips where the engine doesn't get get to full running temperature. Head gasket failures and cracked heads show far more obvious symptoms before you see milky oil.
Lots of moisture is a sign of a problem.
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From: Phoenix
222 S-65
The pressure cap has multiple tasks.... Prevent leaks.... Keep the cooling system pressurized as the coolant expands up to the point where it will blow off pressure to keep radiators, hoses from blowing up.... Allow air to enter the reservoir once coolant has cooled so the cooling system is not ever in a partial vacuum.
