Low coolant levels

[MichaelInChicago]

I checked both coolant reservoirs today (one in the front middle under the engine cover and one on the front right fender near the firewall) and they were both very low.

In the center tank, there was no fluid visible at all (the yellow plastic min/max lines were visible) and on the one nearer to the firewall, there was fluid visible but far down, right at the bottom of the neck.

Do I simply add fluid to both these areas directly? What type of coolant and how much should I buy?

Thanks very much.

[Opie55]

I thought you just checked those? Yes, you add it directly. Buy a liter of BMW coolant and mix 50/50 with distilled water. BMW coolant is blue. Don't mix different coolants.

[MichaelInChicago]

I had received the strips but had time today to do it but could not test the coolant as there wasn't enough to test.

Can I use coolant that I bought at a local store instead of going to a BMW dealer? If so, is there a special coded coolant I have to buy and how much should I be buying? Can I buy a 50/50 premix?

[Opie55]

No, you cannot buy BMW coolant at an auto parts store. And I have never seen it premixed. Somebody may tell you that you can use some different brand, but I would not. What's the big deal about buying a gallon of distilled water for a buck at the grocery store, and you must be near a BMW dealer since you live in Chicago.

[MichaelInChicago]

There is no problem, but we have some 50/50 premix coolant left that we used on another car so I thought I could use it.

[Walt White Coupe]

The front one has a level indicator. The right rear filler tube has no indicator as to when it's full. You have to use a ruler and diagram below.

[Opie55]

For whatever reason coolants are now many different types and nearly brand-specific. BMW is blue, Audi is orange, MB is very pale yellow, etc. Not sure when coolant chemistry started to go in different directions. It used to all pretty much be the same.

[MichaelInChicago]

The one I have is Prestone European Vehicle 50/50 Antifreeze Coolant that says it is ok to use for BMW's as well as other European cars and can be added to any colour antifreeze.

[Opie55]

Yes, I know you can buy coolant that says that. I would not put that in my car. You do what you want.

[Qsilver7]

FYI...in case you can’t read the image Walt posted above...you can make a tool from old chop sticks or a straw etc if you don’t want to stick your ruler down inside the engine coolant fill tube. Measure off two marks...one that is approx 4” from the top and one that is approx 6” from the top...that way you can tell if you have the correct amount of coolant in the engine coolant reservoir:

[JBF650]

Originally Posted by MichaelInChicago

I checked both coolant reservoirs today (one in the front middle under the engine cover and one on the front right fender near the firewall) and they were both very low.

In the center tank, there was no fluid visible at all (the yellow plastic min/max lines were visible) and on the one nearer to the firewall, there was fluid visible but far down, right at the bottom of the neck.

Do I simply add fluid to both these areas directly? What type of coolant and how much should I buy?

Thanks very much.

Yes my little centre reservoir appeared to be empty too! Having not much to do I washed the car today and hosed the engine bay down to remove dust. I was checking levels and thought I would check this and to my surprise it appeared to be completely empty! I’ll take your advice and only use BMW coolant. I’ll buy some from my dealer up the road.
If this system is sealed where would it be leaking too? I know its not the main cooling system but regardless it performs a function to keep the charge intercoolers cool and the computers cool....or so I’ve read.
Does this system bleed back to the main cooling system or is it completely independent? If so could I have a leak I wonder or perhaps it has never been topped up.....
Thoughts

[Walt White Coupe]

If you haven't seen spots on the floor under the car, most likely it's never been touched and since the systems are not completely air tight, evaporation does occur over time. Same thing happened to my 2013 650 last year. Topped both off and so far so good.

[Opie55]

Originally Posted by JBF650

Yes my little centre reservoir appeared to be empty too! Having not much to do I washed the car today and hosed the engine bay down to remove dust. I was checking levels and thought I would check this and to my surprise it appeared to be completely empty! I’ll take your advice and only use BMW coolant. I’ll buy some from my dealer up the road.
If this system is sealed where would it be leaking too? I know its not the main cooling system but regardless it performs a function to keep the charge intercoolers cool and the computers cool....or so I’ve read.
Does this system bleed back to the main cooling system or is it completely independent? If so could I have a leak I wonder or perhaps it has never been topped up.....
Thoughts

I'm pretty sure it's a totally separate system. It runs at much lower temps than the main system. I do not know where it goes. My car was CPO so I assumed everything had been checked. As time went by, I realized nothing had. My main coolant system was down well over a quart. The secondary system reservoir was also dry. So I filled them and then monitored the levels. After some air burps in the main system that required me to top it up, they have stayed pretty stable. So I don't know where it goes. I guess some just evaporates eventually.

[JBF650]

Great thanks guys I’ll get a few litres of the blue BMW stuff tomorrow from my dealer and check both systems and top up the little centre one and keep an eye on it.
WWC, nah I’ve seen a drop of any liquid under the 6series or even smelt coolant so I doubt it’s leaking out anywhere. As you say it’s probably never been addressed in the 4 years the car has been on the road which I’m a little surprised at I would have though better of my dealership to at least check this as it sits right at the front of the engine and isn’t hard at all the check.....
Opie yeah over time it most likely evaporates. The reservoir while not bone dry did have some moisture in it but not much...... the main system when I checked this looked to be ok. I heard a hiss and pop as I undid the cap, of course the engine wasn’t that warm and I smelt coolant so it has volume there.

Thanks all

[MichaelInChicago]

I just spoke with my BMW dealer and they emailed back that unless the low coolant indicator comes on the dash, there is no problem even if the levels in both reservoirs are below minimums when the engine is cold as the sensors in the car are very sensitive and to only pass by for a top-up when the light comes on.

They said to check them when the engine is warm (not cold) after a drive as the coolant expands and that is what the sensors actually measure.

Does that make sense?

[Opie55]

Not a lot of sense, no. They are correct that coolant expands. But what do they mean by warm? If you open the main coolant cap when the car is hot you may get burned. But let's just look at the facts you presented. As to your main coolant reservoir, you said you could see coolant down there. I will guess that is maybe 10" down from the cap because that is about as far as you can see. The correct level is about 5". But, as I said before, it's just a filler tube at that point, so the volumetric difference between 5" and 10" is a cup or so. So you are "fine." The light will come on when you are about a quart and half low. But your dealer's advice to wait until the light comes on is stupid. What if you are on a long road trip? But now lets turn to the other reservoir because that is where the dealer's advice gets really stupid. You said you could not see any coolant in there. Even without any detailed knowledge of cars - but just as a human who has managed to reached adulthood - does it make any sense to you at all that that is okay? Ask your dealer where the sensor for that system is. Get ready for it - there is none. You need to get over your assumption that all dealer employees and other techs are, as you call them, "professionals". Some are good, some are dumb as rocks. And what is a "sensitive" coolant sensor? It is either immersed in fluid or it is not. That's it.

[Frupal]

Holy smokes! I’d better go check my coolant levels!

[MichaelInChicago]

Opie, no need to be so condescending. This is a forum, where people come to ask questions and to hopefully get respectful advice from others, which you have offered so many times.

It actually does sound logical that the coolant would expand when hot so to bring it to the right level, especially in the front center reservoir, where you cannot see the level below the yellow plastic min/max piece. Now that I know there is no sensor there, I will go to my BMW dealer and have them top it off.

[Walt White Coupe]

Opie is just telling you like it is. Take it to a BMW dealer to top it off?? If you can open the cap, you don't need a dealer.

[MichaelInChicago]

Telling me like it is?

"Even without any detailed knowledge of cars - but just as a human who has managed to reached adulthood - does it make any sense to you at all that that is okay?"

That is not telling me like it is. The rest of his answer was, but not this. If you think this is the way we should talk to one another, then please do not respond to my posts any longer.

[Qsilver7]

I just posted the info below this past Saturday over on BimFest. Re-posting here since it seems kind of relevant to this thread and the N63TU engine's cooling system's "circuits" are an interesting conglomeration. And it is slightly different than the N63 engine that preceded it. Hopefully it can help illuminate how the 3 systems are all connected:

To further explain the N63TU’s cooling circuits (there’s 3 of them)...see the information below. Again, this can be confusing because the early models with the N63 engine has a different set-up.

The N63TU has an:

1. Engine cooling circuit
2. Turbocharger cooling circuit
3. Charge Air cooling & DME cooling circuit

The engine cooling circuit does have a coolant level sensor...but again, the n63tu engine coolant reservoir is located in the left fender so that is where the coolant level sensor is located. You can see the location in the first illustration below (look for #4 and #15):

[JBF650]

wooohooo its getting hot in here and I'm not talking about low coolant in our reservoirs!

Gents we should all be respectful of each other indeed. Some people are more mechanically minded than others.

Michael you started this thread and I'm grateful you did! Your question prompted me to check my car. However I would suggest your dealer telling you to wait till a light comes on is absolutely silly and lazy advice particularly as we can both see our little middle reservoir is bone dry... I'm not a mechanic but I know this isn't right and while not hugely problematic I certainly will not be leaving it this way. Was my car cold , yes however even cold there should be fluid in the reservoir. I would caution anyone checking these pressure systems when hot this is how people get burned. Check when warmish for sure but please don't be taking pressure caps of cooling systems after the car has been on a run... this again is very poor advice from anyone.
I would assume yes there are low warnings for main coolant levels but again why would you wait till these come on if you can check it yourselves and top up if necessary.
Some dealers service people are as 'dumb as rocks'. I'm afraid I agree with Opie here .... I have had a number of interactions with some dealers over the years that I suspect would have difficulty finding their arse with both hands.
So.… all that being said , again thanks Michael for brining this to all our respective attention! very interesting and worthwhile thread and will be prompting us all to check these reservoirs regularly! Now I'm off to get some BMW coolant to store in my garage and for a bit of home checking from time to time.

Cheers all