[LUX3]

My 2016 F30 330i has done 28000km since new.
In my ownership over the last year I have driven 6000km, regularly checking the coolant level .
So I'm adding about a cup per 1000km. That's around 2 litres over the year.
There is no visible leaks or sweet smell of hot coolant.
Have tried 2 new caps on the coolant reservoir.
Checked the level about an hour after driving while still hot and there's plenty of pressure so I'm sure it's pressure tight with both caps . No evidence of dried coolant residue around the top of reservoir.
Also loosened the reservoir bleed screw and no air bubbles evident so not a bleeding problem.

So where's the coolant going?
Anyone else have this problem?
What's the fix???

[Aziego]

See my thread.

https://f30.bimmerpost.com/forums/sh....php?t=1908726

Same issue. Had done cap, expansion tank tube and it still consumes coolant. Next on my list is to think about replacing the water pump. I do have higher mileage on my car so may do it as preventive maintenance anyway.

[LUX3]

Hi Aziego
I read your thread; frustrating indeed.
Pretty sure I don't have any leaks because my previous E92 was loosing a small amount of coolant and, whilst it never dripped on the floor, there was always the sweet smell of hot coolant in the engine bay. Eventually pressure test detected hole in radiator where crusty deposits of dried coolant had accumulated. So that was easy fix with new radiator, problem solved in that case.
This car is using a lot more coolant, but no dripping on the floor and no sweet smelling odor of coolant. ... So I'm baffled!
If it's going through the engine, it might show up in emulsion of the oil when I change in a few months, (although oil filler cap is clear). No whispy smoke or odor from the exhaust, but then the quantity being consumed is probably too little to detect in this manner.

Are there many others with this problem?
I have read that B58 owners suffer as well. Similar design engine??

[F32Fleet]

The only way to know for certain is to pressure test the system.

No white smoke - good
No milkshake in oil - good
No oil in coolant reservoir - good.

If all that's good then it's slowly making it's way out by way of the cap. I wouldn't worry about it once you've pressure tested the system.

[damack]

I'm not sure if your 2016 is affected but my 2017 B48 had a service bulletin for a cylinder head ventilation hose. I had some coolant loss over the winter but after I topped a couple of times it never came back. Then I was notified of this hose problem. Dealer fixed it no charge (out of warranty) Here's a thread about it. Some others experienced coolant loss with this issue too.
https://f30.bimmerpost.com/forums/sh....php?t=1889354

[LUX3]

Although I haven't located a leak, I'm considering replacing the cylinder head ventilation hose with the latest version, as preventative maintenance.
I have been told these are prone to failure, and should be replaced every 2 years!!!!!.
I researched and found that the replacement hose could be rubber rather than the original plastic hose.
Did you guys find that the new hose is in fact rubber material?

[Aziego]

At least to my eyes, there is no visible difference as to the materials used in the updated part. It is more likely a different plastic formulation for the plastic connectors as that is the area where it seems to fail at. As others has mentioned, BMW will cover the replacement of the tube (at least in the US).

[LUX3]

Water pump leaking at 28000km!!!!
Finally detected by BMW techs.
So much for buying expensive quality vehicle 😒

[LUX3]

Originally Posted by Aziego

See my thread.

https://f30.bimmerpost.com/forums/sh....php?t=1908726

Same issue. Had done cap, expansion tank tube and it still consumes coolant. Next on my list is to think about replacing the water pump. I do have higher mileage on my car so may do it as preventive maintenance anyway.

BMW service performed a pressure test and NO leaks were detected.
On closer visual inspection it was found that the water pump was weeping coolant, evident by the coolant crystals observed. Just remove the lower cover under the motor and take a look.

[Aziego]

I took the panels off my car today and i do think it is the water pump. It was difficult for me to see as i have xdrive and the front differential blocked the view. But I did see white residue at the top of the water pump housing. So that can only mean that coolant was weeping out.

[amancuso]

I'm having this problem with my 430i. Pressure tested by pumping up to 15 psi and let it sit overnight, by the next morning it had gone down to 14 psi. No leaks (or smells) detected on the ground. Will have to check the bottom of the water pump.

[bluesport]

Keep following the situation for a while before getting into conclusions or replacing parts on hunches.

I had to top at least four times 0.15..0.2 liter of coolant to mine after I bought it second hand. I was about to take to service but then it stopped, I guess air in the system?

After that level has been stable for two years now.

[Aziego]

Originally Posted by amancuso

I'm having this problem with my 430i. Pressure tested by pumping up to 15 psi and let it sit overnight, by the next morning it had gone down to 14 psi. No leaks (or smells) detected on the ground. Will have to check the bottom of the water pump.

The weep hole is on the top of the water pump. Same exact experience, can't smell or see anything until I looked at the weeping hole of the pump.

[amancuso]

Originally Posted by LUX3

BMW service performed a pressure test and NO leaks were detected.
On closer visual inspection it was found that the water pump was weeping coolant, evident by the coolant crystals observed. Just remove the lower cover under the motor and take a look.

Originally Posted by Aziego

The weep hole is on the top of the water pump. Same exact experience, can't smell or see anything until I looked at the weeping hole of the pump.

Lux3, same, but no coolant crystals anywhere near the water pump.