[Cobra358]

Originally Posted by UrbanCarCulture

I doubt BMW would change the water pump without having any warranty since its their manufacture defect?



Im also experiencing that white saltine. Im assuming my coolant lose is not just from this issue around the cap but the actual water pump itself?

Also, should I change the cap as well? I heard that's something that is recommended.

My main tank has been low twice in the last 10k miles, 44k total miles. I have that white residue under the cap. I am wondering if the cap has a design defect and doesn't seal, this would explain why it will still lose water over time even with a replacement cap.

[BWbimmer]

Not sure what age your car is (profile?) but BMW updatet their cap with a new number.
17117639020. Do you want to have a look if you still got the old one?

[calidude]

42K miles and my water pump is leaking and the dealer wants $2,238.45 to replace it and my warranty just expired less than 30 days ago

[BWbimmer]

Originally Posted by calidude

42K miles and my water pump is leaking and the dealer wants $2,238.45 to replace it and my warranty just expired less than 30 days ago

Are you talking about the mechanical one?

https://www.leebmann24.de/kuehlmitte...517643067.html

They must be having a laugh? Will they take the engine out?

[UrbanCarCulture]

Originally Posted by calidude

42K miles and my water pump is leaking and the dealer wants $2,238.45 to replace it and my warranty just expired less than 30 days ago

Dude the pump is under $200 bucks. Plus another $200 for labor at a BMW indie shop, $60 for coolant. Way cheaper and just saved yourself a ton of money.

[Mick.86uk]

Originally Posted by Cobra358

My main tank has been low twice in the last 10k miles, 44k total miles. I have that white residue under the cap. I am wondering if the cap has a design defect and doesn't seal, this would explain why it will still lose water over time even with a replacement cap.

I had the same issue.

Cleaned off all the white residue and applied some silicone grease to the threads.

Cap now screws on and off easily and no coolant loss for over a year - 5k miles.

[dmaxdmax]

I'm 'sipping' very little coolant, but it is going somewhere. Not out the caps. Maybe an ounce every 1,000 miles. I'll get to looking better when it gets worse.

...and now I'm hearing b58s might be having oil pressure issues, though perhaps only in our tuned variants...idk. I'm keeping mine stock and praying!

[Cozmo Kraemer]

I have a coolant issue as well. I had gotten the low coolant warning intermittantly every 6 months or so, for the last year. I just put more coolant in, fine. But this last month, I have gotten the warning 4 times. I always refill... comes back. The last little while I get a puddle under my car some mornings.

Took it to BMW. They pressure test. No issues they say. Send me the video of the inspection, say everything is dry. I see the white residue on parts under the car, but they wont listen to me. If the car leaks on heat soak after shut off... that would probably be cap related? I'm guessing? It's a weird issue no doubt.

[BWbimmer]

If you've got to refill so often now, I would invest in a new lid

[Cozmo Kraemer]

My car is under the full extended warranty. They can deal with it.

[BWbimmer]

Originally Posted by Cozmo Kraemer

My car is under the full extended warranty. They can deal with it.

even better

[blaxer007]

I'm also having the coolant loss problem. Took a guess and replaced the main reservoir cap. That didn't help. Finally found that after the engine reaches operating temperature and while operating around 2500 rpm (in park) the coolant pump appears to be leaking. Ordered a new water pump last week. Hoping that once the old pump is off the failure mode will be obvious. What helped me get to this diagnosis was a very thorough investigation after driving the car and found some small pools of moisture on the plastic underbelly of the car.

[BWbimmer]

Originally Posted by Cozmo Kraemer

My car is under the full extended warranty. They can deal with it.

Was your problem resolved?

[ZoranTerzic]

What year models is this happening to? Does anyone know if they've revised the system on a particular year model?

[kern417]

Originally Posted by ZoranTerzic

What year models is this happening to? Does anyone know if they've revised the system on a particular year model?

My car is a 2018 and had some loss. Also the cause of leaks are pretty widespread, so it could be anything. It's not limited to a specific model year.

[ZoranTerzic]

Originally Posted by kern417

My car is a 2018 and had some loss. Also the cause of leaks are pretty widespread, so it could be anything. It's not limited to a specific model year.

Thanks for the help mate!

[auburnf30x]

Want to add my experience here, hopefully it will help others...

I too, am experiencing coolant loss. 2017 (07/17 SA build) 330i xDrive. Bought in January with 28k miles, now at 34k (REALLY need to stop taking joyrides).

At 31k, was having an issue that I thought had nothing to do with coolant. AC system was short cycling and therefore not working very well. After trying to figure it out myself (couldn't) I brought it to my dealer. They found the secondary coolant tank to be bone dry, the one for the AC and intercooler system. AC was short cycling to protect the engine and prevent overheating. No warning light, but it looks like the auxiliary tank does not have a sensor. Added coolant, pressure tested twice over two days, found no leaks and everying was working great again, so off home it goes.

Now at 34k, I found my AC short cycling again. Popped the cap, and while not bone dry, it was low again. Added coolant and everything is fine again for the time being. I didn't have to add very much, maybe a cup tops.

This thread has given a lot of helpful information, so I'm going to dig further into this on my own and post my results. I have not checked the main tank yet, or checked for evidence of coolant loss near the caps. Naturally, I spilled some filling it so I'm going to have to clean everything off and keep an eye on it.

My guess is, at least in my case, that the cap(s) are the main culprit here. With the small amount lost, regular 3k top off intervals, and two negative pressure tests, it would make the most sense given the consistency and lack of worsening progression.

I'm going to clean, inspect, and fully top off both tanks and caps. I'll monitor them, watch for any signs of leakage, replace one or both caps and return with my results. BTW, caps can be found for $10 each at RockAuto, so if this appears to be increasingly common, it would make a good first start to inexpensively try to correct the issue without a trip to the dealer.

Unless of course, the caps themselves are just a defective design and regular top offs are going to become necessary.

*EDIT* Sorry, didn't read closely enough...thread title clearly says B58 but my mind saw B48. I'll still follow up, might be useful information anyway.

[auburnf30x]

Ok, so a few things...

Part numbers for the coolant caps appear to fit virtually all BMWs made for several model years, regardless of the platform or engine involved. I’d be curious to know if other platforms have the same issue.

I got a recent (last 1000 miles) oil analysis back from Blackstone, no antifreeze at all found in the oil.

I can’t find anything directly saying so, but I’ve gotten the impression that these things are regular wear maintenance items and must be periodically replaced. Given that they are simple mechanical devices with rubber seals working under pressure it would make sense.

Moving on to mine in particular, I found evidence that there is coolant escaping around the cap seals, from one side in particular.





One side shows both the threads and cap have recent residue all the way down to the base.

My main reservoir is full with no signs of recent leaking. Threads and cap are dry. It does, however, show the white dust that others have mentioned as a possible sign of past leaks, so I may replace it anyway.



I’ll report back after I’ve had the new one on for a while to see how it improves.

[BWbimmer]

Originally Posted by auburnf30x

Want to add my experience here, hopefully it will help others...

I too, am experiencing coolant loss. 2017 (07/17 SA build) 330i xDrive. Bought in January with 28k miles, now at 34k (REALLY need to stop taking joyrides).

At 31k, was having an issue that I thought had nothing to do with coolant. AC system was short cycling and therefore not working very well. After trying to figure it out myself (couldn't) I brought it to my dealer. They found the secondary coolant tank to be bone dry, the one for the AC and intercooler system. AC was short cycling to protect the engine and prevent overheating. No warning light, but it looks like the auxiliary tank does not have a sensor. Added coolant, pressure tested twice over two days, found no leaks and everying was working great again, so off home it goes.

Now at 34k, I found my AC short cycling again. Popped the cap, and while not bone dry, it was low again. Added coolant and everything is fine again for the time being. I didn't have to add very much, maybe a cup tops.

This thread has given a lot of helpful information, so I'm going to dig further into this on my own and post my results. I have not checked the main tank yet, or checked for evidence of coolant loss near the caps. Naturally, I spilled some filling it so I'm going to have to clean everything off and keep an eye on it.

My guess is, at least in my case, that the cap(s) are the main culprit here. With the small amount lost, regular 3k top off intervals, and two negative pressure tests, it would make the most sense given the consistency and lack of worsening progression.

I'm going to clean, inspect, and fully top off both tanks and caps. I'll monitor them, watch for any signs of leakage, replace one or both caps and return with my results. BTW, caps can be found for $10 each at RockAuto, so if this appears to be increasingly common, it would make a good first start to inexpensively try to correct the issue without a trip to the dealer.

Unless of course, the caps themselves are just a defective design and regular top offs are going to become necessary.

*EDIT* Sorry, didn't read closely enough...thread title clearly says B58 but my mind saw B48. I'll still follow up, might be useful information anyway.

It's fine, you sharing your findings, it doesn't really matter if it is the B58 or B48 since the cooling system is basically the same.

Thanks

[kern417]

Originally Posted by auburnf30x

Ok, so a few things...

Part numbers for the coolant caps appear to fit virtually all BMWs made for several model years, regardless of the platform or engine involved. I’d be curious to know if other platforms have the same issue.

I got a recent (last 1000 miles) oil analysis back from Blackstone, no antifreeze at all found in the oil.

I can’t find anything directly saying so, but I’ve gotten the impression that these things are regular wear maintenance items and must be periodically replaced. Given that they are simple mechanical devices with rubber seals working under pressure it would make sense.

It's not a wear item but it is something that can fail just like any other seal. But people like me that experienced coolant loss while my car was <10k miles indicates they had a bad batch of caps.

[JoHnMuir]

I chased this issue around for a few months, today I discovered that my issue is a leaking water pump seal. So, anyone whose issue is not solved by cap replacement may want to check there.

[cfm56d7b]

Originally Posted by JoHnMuir

I chased this issue around for a few months, today I discovered that my issue is a leaking water pump seal. So, anyone whose issue is not solved by cap replacement may want to check there.

How many miles are on your vehicle? Was the issue diagnosed by the dealer?