[1/2M]

Hi everyone, today while refilling the coolant which I have to do every two months due to it getting low fast, I noticed some of it had come out of the smaller reservoir( the one connected to the turbo if im correct) and both lids are very loose, while before I had a really hard time removing either one. While I assume shrinking can happen in the winter this seems excessive. Second I noticed a second leakage at the engine block on right side towards the windshield as you’d be looking from the front , right where the upper part of the engine connects with the bottom one. Anyone had similar experience and care to share what this might be due to, what it means in mechanical terms and wether I should have it checked out? Btw car has 24k miles, m240i and never had an issue except the coolant dropping fast. I don’t notice anything different about the cars behavior and no dash light. If you need extra info about the situation lmk.
Thanks all

[Hap]

With that many miles I would be checking in with dealer.
Keep this updated please.

[BEM-S4]

This seems like a no-brainer, take it in for a warranty repair. Your car should not be losing coolant that fast - if at all.

[1/2M]

Thanks, I’ll make an appointment. I wanted to know if its still safe to drive until I get to them. I removed the engine cover and noticed more on top and probably that’s where it first leaked from.

[morphomeman]

These engines do not normally lose coolant.
GO TO THE DEALER AS SOON AS YOU CAN GET THERE!

[1/2M]

Tnx for the extra input

[XutvJet]

The B58s are well known for loosing coolant or at least the water in the coolant is evaporating off. The N55s do this to some extent as well but the B58 really seems to "consume" a decent amount of coolant. It's hard to say if you're B58 is really leaking coolant or not. I'd top off all the reservoirs with BMW coolant or distilled water and go to the dealer as soon as you can.

[1/2M]

When I first got the car, I read on this forum to get accustomed with the pros and cons of this model and quite a few people mentioned the coolant problem and that they just refill it more often. Now wether that’s the case with all of them or just a random thing from manufacture and based on driving habits etc it’s hard to know, but at this point it seems that the leak on top of the engine is very plausible to be linked to the coolant reservoir one.
I added coolant and hope it runs ok until I get to Bmw
From your experience warranty should cover it? Maybe get an m2 in exchange if I pressure them enough... kidding
Now from the category “just for laughs” where is the turbo in this car? That should easily tell you that besides mirrors and front grills I ain’t done much modding to this car ��.
Thanks

[AndDown]

A coolant that’s leaked out will dry leaving white residue - common issue with the E46 engines around the coolant reservoir that was a tell tale sign the reservoir was splitting.

[USA-RET]

Originally Posted by BEM-S4

This seems like a no-brainer, take it in for a warranty repair. Your car should not be losing coolant that fast - if at all.

Echo that.

[1/2M]

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[1/2M]

Agreed

[keylime503]

This seems to be a really common issue with the B58 engine. Almost every time I manually check the coolant levels, it's really low. However, I've never once gotten a warning light or had any issues. I've taken the car to the dealer three separate times (and two different dealers) for this issue, and each time they just say "we can't find anything wrong with your car, just top it off and don't come back unless you get a warning light".

[1/2M]

It definitely seems like a common problem and the problem with it, is that you don’t get a light unless it’s almost dry and to me thats what makes it worse, because if you forget to check it in time bigger things can happen, so you’re better off setting a monthly alarm and check it.

[harma24]

Originally Posted by 1/2M

Btw car has 24k miles, m240i

For comparison, I have a 2017 M240 with >80k miles. I've had the coolant light come on twice (once within the first 6 weeks of ownership, another before the end of that first winter), and I've had to top it off once or twice since then (3-4 times total in nearly 3-1/2 years of ownership). If you're filling it more than that and you're still under warranty, definitely bring it back! That is not normal behavior for the engine.

[Hap]

With this engine using coolant my question is where does it go ?
If you don’t have overflow when parked and no leaks visible where is coolant disappearing to ?

Just trying to learn
Hap

[morphomeman]

It is going into the air, evaporating!
The question is where is it evaporating from.

[1/2M]

Took it to Bmw and supposed to pick it up later today. Will update with what they did and concluded.

[Maynard]

I hear that sometimes it is getting sucked into the turbos? Or is that just oil that can find its way into the airstream?

[1/2M]

So, they changed the bigger coolant tank, but the lids are still much looser than before and at the engine bay they didn’t seem to have done anything since the liquid spill is still there, but I didn’t ask again since I already pointed it out when I brought the car in so I’m assuming they didn’t find it important to look at. I think the reason why the coolant is dropping so fast is less relevant at this point since it happens to so many people and the take away is check it out every 30-45 days and top it off , rather than trying to figure out this and that as long as it’s not causing any other inconvenience. Cheers

[XutvJet]

Remember that coolant is largely comprised of water and water evaporates over time. In my prior non-BMW cars and my wife's current 2015 Outback, it's common for me to add some distilled water to the overflow tanks every 3 to 4 months. I have to do the same to my M235.

Contrary to belief, the cooling systems in these cars are not air tight and they can lose water to evaporation over time, especially considering that these are hot running turbo cars. The N55s have had a history of losing coolant and the B58 more so. My guess is the evaporation is occurring at the caps.

The thing that worries me about the B58 is that the intercooler is liquid to air and is just in front of the intake ports. The M series S55 used in the M2/3/4 has the same general design and there is an issue with the intercooler leaking coolant straight into the motor. Yikes! I hope these B58s aren't having the same issues. I wonder if the techs are scoping the intake manifolds to verify that this is not happening.

[Shovelman]

My B46 gave me a light at 42,000 miles. I called the dealer and was told that "these engines use some antifreeze, just top it off" which I did and am not worried.

However engines do not use antifreeze, they can only leak it. A tiny leak into the combustion chambers should not cause any harm but a bigger leak might. This type of leak is hard to prove and hard to fix. Mine is likely of this type. Any leak to the outside of the engine is clearly a leak and the dealer should fix it under warranty.

One other problem is with overfilling, which can cause the engine to spit the excess out.