low coolant level
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low coolant level
2017 gls550 with 120K km..
so I have some heat related issue and an indy shop replaced the water pump and a few coolant lines. the heat seems to be improving but I had a coolant low level after driving 150km or so.
topped up the coolant and it was low again. based on my estimate, i have to top up 800mL of coolant for every 150 km driven. it seems that the coolant is "disappearing" at a rate of 6ml/km driven.
brought the car back to the shop and they found a leak on one of the pressure relief lines after the pressure test. the line was replaced however the symptom persists.
I brought the car back again today and they performed pressure test again without finding any issues..
i do find small drips of pink coolant on the floor sometimes but it is not consistent.
engine oil looks clean so they don't think it is head gasket.
just to add that since the water pump was replaced, i drove about 700kms and i topped up about 3L of coolant mix..
what else can be the issue? anything that the pressure leak test won't detect?
so I have some heat related issue and an indy shop replaced the water pump and a few coolant lines. the heat seems to be improving but I had a coolant low level after driving 150km or so.
topped up the coolant and it was low again. based on my estimate, i have to top up 800mL of coolant for every 150 km driven. it seems that the coolant is "disappearing" at a rate of 6ml/km driven.
brought the car back to the shop and they found a leak on one of the pressure relief lines after the pressure test. the line was replaced however the symptom persists.
I brought the car back again today and they performed pressure test again without finding any issues..
i do find small drips of pink coolant on the floor sometimes but it is not consistent.
engine oil looks clean so they don't think it is head gasket.
just to add that since the water pump was replaced, i drove about 700kms and i topped up about 3L of coolant mix..
what else can be the issue? anything that the pressure leak test won't detect?
Last edited by nioero; Feb 10, 2025 at 04:10 PM.
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From: unbegrenzt
2017 GLE350 4MATIC
Reservoir leak
hose leak
oil cooler leak
transmission cooler leak
radiator leak
You need to see exactly what is leaking. This requires an hour of careful inspection with a bright LED flashlight.
hose leak
oil cooler leak
transmission cooler leak
radiator leak
You need to see exactly what is leaking. This requires an hour of careful inspection with a bright LED flashlight.
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they told me that the coolant system holds pressure.
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2017 GLE350 4MATIC
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the oil was checked and i dont see any milky stuff. Also there is no unusual amount of white smoke other than what can be seen in a typical winter. I just found it odd that this happens after the indy shop replaced the water pump and a few coolant lines.
my b1 service is due in a few weeks and i will bring the car to another reputable shop in my area to do the service and will see if they can found anything.
my b1 service is due in a few weeks and i will bring the car to another reputable shop in my area to do the service and will see if they can found anything.
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From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
Check the radiator hoses an hour or two after driving the car. If the head gasket is leaking to the cooling system the hose will likely be rock hard. Also, 27 oz in 80 miles, or 800 ml in 130 km, or a quart in 100 miles, all would make a lot of smoke.
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Phew then it is not a head gasket.
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I found it too coincidental that it got worse after the water pump was replaced. I did have to top up coolant once or twice a year since 80k km but it was nothing like now.
maybe the old pump was faulty and the new one made the leak worse since it pumps better now?
maybe the old pump was faulty and the new one made the leak worse since it pumps better now?
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From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
Does your water pump have a vacuum line connected to it? My GLK has a vacuum line that actually closes off the water pump when the engine is cold. It makes the engine warm up quickly, but the mechanism can leak, allowing the vacuum system to be contaminated with coolant, and causing a slow loss of coolant. Nothing like 800 ml in 130 km, though.
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Does your water pump have a vacuum line connected to it? My GLK has a vacuum line that actually closes off the water pump when the engine is cold. It makes the engine warm up quickly, but the mechanism can leak, allowing the vacuum system to be contaminated with coolant, and causing a slow loss of coolant. Nothing like 800 ml in 130 km, though.
the indy shop did replace 4 hoses while they were at it. I was told those lines are brittle though i have no idea what they are except for generic terms like “ coolant line” or “ coolant return line”.
Last edited by nioero; Feb 12, 2025 at 11:33 AM.
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2017 gls550 with 120K km..
so I have some heat related issue and an indy shop replaced the water pump and a few coolant lines. the heat seems to be improving but I had a coolant low level after driving 150km or so.
topped up the coolant and it was low again. based on my estimate, i have to top up 800mL of coolant for every 150 km driven. it seems that the coolant is "disappearing" at a rate of 6ml/km driven.
brought the car back to the shop and they found a leak on one of the pressure relief lines after the pressure test. the line was replaced however the symptom persists.
I brought the car back again today and they performed pressure test again without finding any issues..
i do find small drips of pink coolant on the floor sometimes but it is not consistent.
engine oil looks clean so they don't think it is head gasket.
just to add that since the water pump was replaced, i drove about 700kms and i topped up about 3L of coolant mix..
what else can be the issue? anything that the pressure leak test won't detect?
so I have some heat related issue and an indy shop replaced the water pump and a few coolant lines. the heat seems to be improving but I had a coolant low level after driving 150km or so.
topped up the coolant and it was low again. based on my estimate, i have to top up 800mL of coolant for every 150 km driven. it seems that the coolant is "disappearing" at a rate of 6ml/km driven.
brought the car back to the shop and they found a leak on one of the pressure relief lines after the pressure test. the line was replaced however the symptom persists.
I brought the car back again today and they performed pressure test again without finding any issues..
i do find small drips of pink coolant on the floor sometimes but it is not consistent.
engine oil looks clean so they don't think it is head gasket.
just to add that since the water pump was replaced, i drove about 700kms and i topped up about 3L of coolant mix..
what else can be the issue? anything that the pressure leak test won't detect?
so since the water pump replacement, i topped up maybe 80-100oz or so coolant and all of a sudden it stopped disappearing. Could it be all air pocket? I found it hard to believe.
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just an update: after the 3rd visit to the indy ( i was told that they didnt do anything except verifying that everything’s okay) i drove maybe another 160km or 100 miles i was expecting to fill up another 20oz or so. But to my surprise, the coolant level didn’t drop at all this time!
so since the water pump replacement, i topped up maybe 80-100oz or so coolant and all of a sudden it stopped disappearing. Could it be all air pocket? I found it hard to believe.
so since the water pump replacement, i topped up maybe 80-100oz or so coolant and all of a sudden it stopped disappearing. Could it be all air pocket? I found it hard to believe.
i guess it is kind of acceptable. Based on how much i drive i might have to consume a standard merc jug of coolant a year.
Last edited by nioero; Mar 29, 2025 at 10:59 AM.
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another update on this. So I drove another 670 miles but had to top up 29 oz or so coolant. Definitely better than before but still have to top it up every fill-up of gas.
i guess it is kind of acceptable. Based on how much i drive i might have to consume a standard merc jug of coolant a year.
i guess it is kind of acceptable. Based on how much i drive i might have to consume a standard merc jug of coolant a year.
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when i did my b1 service at another indy shop a couple of weeks ago they didn’t notice anything but did notice that water pump and a few coolant lines are new ( i didn’t tell them water pump was recently replaced)
i also replaced the coolant reservoir cap myself a couple of weeks ago.
i didnlt notice leaks on the floor or anything this time.
i think that is about it. The car did start to require coolant top ups since maybe 2022 but less often for sure.
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From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
Unless there is a known issue, like a vacuum controlled water pump, I'd probably test the coolant for combustion byproducts.
Does the cooling system stay pressurized after it cools down? Does the exhaust have a "sweet" smell, or excess water vapor or white smoke?
Does the cooling system stay pressurized after it cools down? Does the exhaust have a "sweet" smell, or excess water vapor or white smoke?
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When it first started right after water pump replacement it was missing 10x rate of now, the shop basically told me it would be white smoke galore jf the coolant is leaking through the head gasket and it wasn’t the case.
i think the shop did something when i visited them the last time since it is disappearing at a much slower rate now. They just kept telling me everything is fine and they couldn’t find anything.
Last edited by nioero; Mar 29, 2025 at 12:37 PM.
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'17 GLS450, '14 GLK250, Grandpa's Roadster
Did the problem start with the water pump replacement, or was the water pump replacement an attempt to fix the problem?
How about pressure? Does it dissipate when the system cools?
How about pressure? Does it dissipate when the system cools?
