Engine Coolant Level
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Joined: Apr 2009
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From: Alexandria, VA
07 E63 AMG, 10 C63 AMG, 07 E63 Designo, 07 E350, 09 C300, 07 C230
Engine Coolant Level
Check this out.... Last Sunday, before departing to Pittsburgh, PA from VA, I did a pre-trip inspection and the only thing, that I found was low engine coolant.
So I filled it up, fast forward to Monday, I did another pre-trip inspection before heading back home, and the coolant was low, so I again filled it up.
Come Tuesday, I checked it again, and the level was at the same level that it was filled to on Monday, the same for Wednesday and again this morning.
Why would the coolant be down, for two straight days in a row, and the last three days the level is full. Someone explain this to me. I was thinking that I have a leak somewhere.
I just had the radiator replaced a few months ago, and last year I replaced the coolant reservoir. I informed my tech that I will monitor it, and provide feedback.
This is really baffling.....
So I filled it up, fast forward to Monday, I did another pre-trip inspection before heading back home, and the coolant was low, so I again filled it up.
Come Tuesday, I checked it again, and the level was at the same level that it was filled to on Monday, the same for Wednesday and again this morning.
Why would the coolant be down, for two straight days in a row, and the last three days the level is full. Someone explain this to me. I was thinking that I have a leak somewhere.
I just had the radiator replaced a few months ago, and last year I replaced the coolant reservoir. I informed my tech that I will monitor it, and provide feedback.
This is really baffling.....
my guess - it could have had air pockets in the system from the replacement parts and your road trip massaged them out,, turn on the heater and run it around too,, there are a couple of valves that may not have opened to allow good flow , I would keep an eye out and do a pressure check on the system, ,, if it continues to go down it could be a simple hose connection,. water pump, or worst case its getting sucked into your cylinders via head gasket (but you would likely see white smoke from tailpipe) - do the pressure test - can do them yourself with inexpensive equipment
Thread Starter
MBWorld Fanatic!
Joined: Apr 2009
Posts: 6,024
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From: Alexandria, VA
07 E63 AMG, 10 C63 AMG, 07 E63 Designo, 07 E350, 09 C300, 07 C230
I will try the heater in the morning, as it's too dam hot to be using the heater after work. 
I'm prepared to monitor this for a bit longer. Don't want to over react, I'm planning on visiting my shop next week anyway, for them to do a pressure test of the system. If the coolant level shows signs that it is down for whatever reason, I will take it in sooner. Also I'm installing my new CF instrument cluster cover. And if it has arrived in time, install my new CF interior trim pieces. It may be a blessing that I'm getting new head bolts installed next month. Fortunately, no white smoke from exhaust, which is a good Omen. 
I'm prepared to monitor this for a bit longer. Don't want to over react, I'm planning on visiting my shop next week anyway, for them to do a pressure test of the system. If the coolant level shows signs that it is down for whatever reason, I will take it in sooner. Also I'm installing my new CF instrument cluster cover. And if it has arrived in time, install my new CF interior trim pieces. It may be a blessing that I'm getting new head bolts installed next month. Fortunately, no white smoke from exhaust, which is a good Omen.
Last edited by Yuille36; Aug 22, 2019 at 08:52 AM.
Thread Starter
MBWorld Fanatic!
Joined: Apr 2009
Posts: 6,024
Likes: 532
From: Alexandria, VA
07 E63 AMG, 10 C63 AMG, 07 E63 Designo, 07 E350, 09 C300, 07 C230
Good News, no more low coolant levels. I honestly don't know what the issue was, but my coolant level has stayed consistent for the last five days.
I know that we have an overflow, could that have caused the heated coolant to discharge, thereby given me a low coolant level. I tried a experiment this morning, by driving the car with the heater on.
I then checked it again, when I filled up with gas, and the coolant level did increased the the point where some overflowed out of the reservoir, keep in mind that the coolant wasn't blazing hot, but hot enough to get burned.
I think that might have been the cause of my issue. Any opinions on this???
I know that we have an overflow, could that have caused the heated coolant to discharge, thereby given me a low coolant level. I tried a experiment this morning, by driving the car with the heater on.
I then checked it again, when I filled up with gas, and the coolant level did increased the the point where some overflowed out of the reservoir, keep in mind that the coolant wasn't blazing hot, but hot enough to get burned.
I think that might have been the cause of my issue. Any opinions on this???
Thread Starter
MBWorld Fanatic!
Joined: Apr 2009
Posts: 6,024
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From: Alexandria, VA
07 E63 AMG, 10 C63 AMG, 07 E63 Designo, 07 E350, 09 C300, 07 C230
I will have Benz Elite Automotive perform a pressure test, on my coolant system this Friday, for peace of mind. Until I get the head bolts changed out next month.
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I wouldn't pressurize the system, just wait until after you do the head bolts. Then if you have a leak do the pressure test. I would just look around for coolant leaks. Look around clamps and fittings and check hoses for now.
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Thread Starter
MBWorld Fanatic!
Joined: Apr 2009
Posts: 6,024
Likes: 532
From: Alexandria, VA
07 E63 AMG, 10 C63 AMG, 07 E63 Designo, 07 E350, 09 C300, 07 C230
And has been normal ever since Aug 20th. I understand expansion and contraction, with regard to fluid dynamics. So I thought maybe, I had a coolant leak somewhere.
I will follow your guidance, as they will have to pressure test the system anyway after replacing the head bolts.
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Thread Starter
MBWorld Fanatic!
Joined: Apr 2009
Posts: 6,024
Likes: 532
From: Alexandria, VA
07 E63 AMG, 10 C63 AMG, 07 E63 Designo, 07 E350, 09 C300, 07 C230
Well, we've determined that I had an anomaly. No engine coolant in the oil, so no milkshake, no leaks anywhere. We figured that maybe the heater core valve was shut, and when it finally was opened that was the cause of my low coolant level.
It was hot when I had the coolant changed last. So go figure.
It was hot when I had the coolant changed last. So go figure.
