[Ifellapart]

Hello all, I've read quite a few stories on here about the B58 eating up coolant. My 340i unfortunately has the same issue. Since i've owned the car (about a year and a half now) I've had to fill up the coolant reservoir about 4 times. I've also told the dealer about it twice when I've taken it in for oil changes. They pressure tested the system twice and found no issue. My understanding is the system is a closed pressurized system, where can the coolant be going?

[G.Newt]

For most of us, it was just under filled from factory (common sense theory). After about 9-12k miles, we'd get a low coolant warning. Like you, I read the stories and had them top off the coolant and pressure test the system and found nothing. Haven't had a coolant warning since then (at 36k miles now).

[B58togo]

I got the first warning @ 19,500 miles and had to add 24 ounces. After that I started monitoring it and had to add another 24 ounces at around 39k miles. Currently at 52k, so need to check it soon! I don't buy the underfilled theories at all.

[Ifellapart]

Originally Posted by B58togo

I don't buy the underfilled theories at all.

Neither do I. It's gotta be going somewhere...I read that it's possibly the cap itself not tightening properly causing some coolant to be steamed off, but i've also read about a turbo being replaced by BMW to solve the issue

[eksigned]

i've also had this issue. i just check it regularly now. '18 440i that i've had for about 3 years now, albeit i've only had the light once.

[G.Newt]

Originally Posted by Ifellapart

Neither do I. It's gotta be going somewhere...I read that it's possibly the cap itself not tightening properly causing some coolant to be steamed off, but i've also read about a turbo being replaced by BMW to solve the issue

Stumbled upon this: https://www.2addicts.com/forums/show...8&postcount=11

Looks like the under-filled theory was incorrect. Rather, they weren't properly bled from the factory.
Aaaaaaand leaky BMW water pumps are still an issue N54 boys are laughing at us somewhere.

[cfm56d7b]

Adding more information to this thread.

My car: 2017 BWM 440i GC. 29.1K miles.

Started losing coolant in September 2019. The dealer replaced the main tank reservoir cap (a known issue) after finding dry white residue under the cap. Cold and hot pressure test revealed no leaks.

Coolant loss (albeit slow) continued. The vehicle was brought to the dealer in early July 2020. Again, cold and hot pressure test revealed no leaks. I escalated to BMW NA requesting turbocharger be inspected before the warranty expires in September. Waiting for a response.

My local BMW dealer contacted field engineer to follow up on the reported issue (see below) that slow coolant leak was addressed by replacing the turbocharger. No response. The dealer installed tamper proof seals under coolant reservoir caps and asked me to return if low coolant warning appears.

Note of interest:

bayern68 based in France reported that "turboloader changed yesterday on warranty after low coolant message at 12k miles. According to the mechanics, turbo was leaking coolant water, but only internally, that's why no water leakage under the car. Water evacuated through exhaust pipe. Although the leak was very small. Dealer also said it's a known issue on B58 2016 production."

https://f30.bimmerpost.com/forums/sh...1324221&page=5

[lcs1956]

The B58 is vacuum filled at the factory (air sucked out and coolant sucked in) followed by the program bleed. The dealer is required to perform the same procedure when servicing the system. My guess is several bleed cycles may be required and some vehicles are sold with air pockets remaining that eventually bubble up to the expansion tank.

[cfm56d7b]

Following up on an open question: did anyone have the turbocharger replaced as a result of a coolant leak?

Please provide as much information as you can. Repair order with any TSB reference would be greatly appreciated.

[cfm56d7b]

Originally Posted by cfm56d7b

Following up on an open question: did anyone have the turbocharger replaced as a result of a coolant leak?

Please provide as much information as you can. Repair order with any TSB reference would be greatly appreciated.

Bump ... will be grateful for more details.

[_N54]

I have a feeling someday were all going to find out the cooler inside the intake manifold will need to be replaced. Even with my Pure Stage 1 turbo i would occasionally lose coolant. No external leaks and def not the heater core since it never smelled like coolant.

[kern417]

Originally Posted by ///S58

I have a feeling someday were all going to find out the cooler inside the intake manifold will need to be replaced. Even with my Pure Stage 1 turbo i would occasionally lose coolant. No external leaks and def not the heater core since it never smelled like coolant.

Most of us are losing coolant in the engine cooling system, not the IC circuit.

[_N54]

Originally Posted by kern417

Most of us are losing coolant in the engine cooling system, not the IC circuit.

Interesting. I would have to top off both my reservoir at times.

[conejodenieve]

I had the same issue recently. They did a pressure test on mine and ended up swapping out the water pump. I was thinking that mine was going to be a faulty seal on the reservoir cap or something

[Ifellapart]

Originally Posted by kern417

Most of us are losing coolant in the engine cooling system, not the IC circuit.

Yeah this ^. Hadn't had any issues with the smaller reservoir, it has been 100% consistent.

[K13GRY]

Recently picked up a 340i... Upon checking fluids, I noticed the engine coolant reservoir was low, needed approx. 300ml top-up.

I've heard stories of the caps losing pressure and coolant escaping from there, I'll keep an eye on mine.

[Wires]

Originally Posted by lcs1956

The B58 is vacuum filled at the factory (air sucked out and coolant sucked in) followed by the program bleed. The dealer is required to perform the same procedure when servicing the system. My guess is several bleed cycles may be required and some vehicles are sold with air pockets remaining that eventually bubble up to the expansion tank.

I'm willing to bet that the dealer just doesn't do this, and that's why it shows up. If 1/10 cars every experience the low coolant, it would make greater financial sense to do nothing, and wait for the owner to drive into the dealership for a free top up.

In my case, I grabbed a jug from the shelf since I wasn't willing to drive to the dealership. They win 2x.

[M_I_N_D]

I've had to top mine up once in the main reservoir and once in the turbo reservoir in my first year of ownership.

Didn't get an alert for low coolant since (more than a year now) but still keep a bottle of distilled water/coolant mixture in the trunk just in case :P

[Tkent818]

https://www.bootmod3.net/log?id=5f24...729b1e5579ae1f

I'm posting this log to show coolant temp deviation. It peaked at 242 degrees before going down but didn't go down too much. Ambient temp is 90 degrees, and not a ton of throttle. I checked the bigger reservoir yesterday and saw it was below minimum so I added some oreilly 50/50 to the max. Before adding I had gone on a trip to Arizona with ambient temps over 100 degrees and A/C on and didn't see coolant temps over 210. I'm concerned about the way I added the coolant, not vacuum pressure added? 242 albeit as peak and not holding seems pretty hot and the fact that it wasn't running that hot before I added has me concerned. Please let me know what you guys think

[Wires]

There should be no issues adding coolant like that. The only time you need a vacuum fill is when you drain the coolant system, and there is air pockets in the lines/cores/block.

I've never looked religiously at my temps, but it seems you are running around 225F, with a 115F IAT temp which seems normal. Stolen from another thread about the N55:

"On the f30 N55, I think you can say the normal op temp is between 210 F (about 10 o'clock on the gauge) and 250 F. At those temps the ecu controls the amount of oil flow from the oil pump through the oil cooler, depending on the load being placed on the engine. At relatively light loads and relatively low rpms, the ecu lets the temp get up to 240/250. The oil is thinner at that temp and fuel economy increases, but the oil still does a good job of lubricating under the light load conditions. If you start to exercise the engine, the ecu drops the oil temp to about 210 (which is where most modern engines with syn oil run today) to increase the lube cushion under heavier load/rpms. Pretty clever."

[Tkent818]

Originally Posted by Wires

There should be no issues adding coolant like that. The only time you need a vacuum fill is when you drain the coolant system, and there is air pockets in the lines/cores/block.

I've never looked religiously at my temps, but it seems you are running around 225F, with a 115F IAT temp which seems normal. Stolen from another thread about the N55:

"On the f30 N55, I think you can say the normal op temp is between 210 F (about 10 o'clock on the gauge) and 250 F. At those temps the ecu controls the amount of oil flow from the oil pump through the oil cooler, depending on the load being placed on the engine. At relatively light loads and relatively low rpms, the ecu lets the temp get up to 240/250. The oil is thinner at that temp and fuel economy increases, but the oil still does a good job of lubricating under the light load conditions. If you start to exercise the engine, the ecu drops the oil temp to about 210 (which is where most modern engines with syn oil run today) to increase the lube cushion under heavier load/rpms. Pretty clever."

Ok cool, thanks

[Supr3me]

I'm curious about how the vacuum filler technique works exactly.


When I upgraded my turbo I did not use the vacuum filler technique and ever since then it's driven me crazy to think there might be air gaps in the system. I've driven thousands of miles and kept an eye on the coolant levels and they're very stable. But still, I wonder....

I have an appt at the dealership on Thursday for something unrelated - can they hook up the vacuum filler and quick check to see if it needs more coolant? Or would it require a full flush and fill?