The dreaded 'top up coolant' warning, but level is fine?

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Fivehunnit

Active Member
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Jun 26, 2015
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203
Car
CLS63 AMG (W219)
So after a dreaded 'top up coolant' warning on my CLS63, I checked the water level and it's pretty much where it's been for the last 6 months Oil level has gone down very slightly if anything, not risen, no excessive white steam from exhaust even in this cold weather, only thing I can think of that may have caused that is I was parked on a very steep incline when I started it up and got that message? No misfires or CEL, thoughts?
 
Top the water level upto where it should be, make a note of the mileage and drive it until you get the message next time is what id do.

Maybe nothing to worry about, Most AMG engines use a little bit of oil "so ive been told"
 
So after a dreaded 'top up coolant' warning on my CLS63, I checked the water level and it's pretty much where it's been for the last 6 months Oil level has gone down very slightly if anything, not risen, no excessive white steam from exhaust even in this cold weather, only thing I can think of that may have caused that is I was parked on a very steep incline when I started it up and got that message? No misfires or CEL, thoughts?

Parked on steep incline.............I think you have answered your own question.
Tony
 
Parked on steep incline.............I think you have answered your own question.
Tony

Parked there a few times before and it never happened, topped up and will see how it goes
 
How much did you have to top up to the correct level?
Half a cup I would imagine.
Tony
 
Lots of hard driving after topping up, level hasn't moved. I guess it doesn't totally rule out slow coolant loss via a stretched bolt etc?
 
When I topped up, I added until the level was just barely covering the tops of these cells, then overnight the level dropped very slightly with the cold temps to here
image.jpg

Then for the last few days, it's been ranging from here when cold, to about 1cm from the lid when hot, the level rises by around 2" after driving, I'm not sure if there's a secondary valve somewhere that helps prevent coolant gushing out if you open the cap when hot, but I unscrewed it earlier and saw coolant beginning to run under the tank along the metal plate, but checking all around the cap as this was happening, none was coming from there
Anyhow, if all's well, it's certainly a wake up call to get the weistec studs in there.
 
Top the water level upto where it should be, make a note of the mileage and drive it until you get the message next time is what id do.

Maybe nothing to worry about, Most AMG engines use a little bit of oil "so ive been told"

Yeah so I hear also, what I was wondering is, if the coolant was contaminating the oil, would the oil not be higher than before? Or could this also be variable depending on whether or not oil is entering combustion chambers along with coolant?
 
Just now...image.jpg
 
Update: the level when cold sits around the same place as the initial pics, varying depending on how cold it is (particularly cold the last 2 days) it goes from there to anywhere between the top of the White plastic tab and the lid depending on how hot the engine is, after topping up to the white tab, it went below there after diving and letting it sit overnight, and noticing almost daily wet patches of coolant on top of the expansion tank as if it's been pushed out of there, but in all, I can't say for sure if any has been lost, other than bits here and there out of the cap? I daily the car, thinking it would be much more apparent than this if it were a stretched or snapped bolt?
Also (I know it's far from the most conclusive test) I took out the oil dipstick while the engine was hot and reached it down and dropped some onto the cat to check for sizzling, no sizzle.
 
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Update, all seems well with the coolant level despite many miles, over 1,000, every report I've seen of the head bolt issue varied from there being no symptoms to instantly CEL, steam and misfires to gradually losing coolant, but even the cases where 'slow' coolant loss was the first signs, they were losing a lot more than this maybe seemed to have, unless there are any of which I'm unaware?
 
Ok update, to me there does seem a very slight loss now, when I topped up, I ensured it was cold and level on my driveway, I topped up to cover the 'tab' which sticks up inside the tank, which the manual states is minimum cold level, now after over a month, the level has dropped around 2cm to the seam of the tank, between the black half and white half, the tab sits higher than this by a few cm, other models such as the C63 don't have this tab and the level is stated as being between the black and white seam correct me if I'm wrong?
Will continue to monitor this and prepare for the new studs to be installed.
It's certainly the slowest loss of coolant I've seen reported if the bolts are either stretched or corroding, usually within a week people reported that the tank was very noticeably drained of coolant, that's the ones which didn't have the very sudden loss and engine light and rough running, steam etc.
 
In the process of: updated head bolts, SLS valve buckets, iPE headers with catless down pipes and a custom map with MSL, acid worked around my budget and soon I will be making the trip to finally see this awesome place I've heard so much about.
 

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