[fpvsportsguy]

My 2017 530i with 120k miles just started dripping coolant pretty fast out of nowhere while parked last week. I've replaced the turbo coolant lines and the coolant reservoir return lines a couple of months ago and they still are holding just fine. I could not see where the leak was coming from top of the engine bay, even after jacking the car up, removing the underbelly panel, I still could not quite tell where it was coming from. The acoustic shield around the oil pan were all soaked and dripping, but still no obvious broken pipes/lines were in sight.

After some research, apparently this was quite common on the 330i with the B48 engines as well. The culprit was the oil filter housing, which of course is made of plastic, and one of the coolant passage gets brittle with time and would crack. See attachment, this is what mine looked like compared to a replacement. Notice right in the center, the housing is missing a big piece of the lip. The updated part had more reinforcement right around that area, indicating that BMW knew this was a problem but choose not to issue any service bulletins or extended warranties. Shame on them.

Anyways, this fix was not for the faint of the heart. It requires removing the intake manifold, which in turn requires a ton of hoses and lines to be disconnected. The manifold is held down by two easily visible e-torx bolts, 3 T30 bolts on the throttle body, and 5 very hard to see 10mm bolts buried around the wires by the intake ports.

And that's not even the hard part. The oil filter housing has 4 E10 bolts, left top and left bottom is easy, but right top is buried under even more wires and right bottom is basically blind and you have to reach around from under the car. Having a swivel E10 socket helped immensely, but these two were still the most difficult bolts I've removed in my life. At one point I was planking over the engine bay with one foot against my garage wall in order to reach.

While you're in there, chances are the engine block coolant connector (11118511205) is gonna need replacement too. It's a $10 part, just replace it so you don't have to remove the intake manifold again in the future for this job. After putting everything together, refill the coolant (about 1.5 gal in my case), start the engine and let it idle, check for leaks, top off coolant as needed. Pat yourself on the back since you just saved 3000 dollars by not going to the dealer.

One thing I'm curious about, and if anybody has experience please chime in, is the quality of aftermarket aluminum housings. I see them all over ebay for not much more than the plastic ones. Do these hold up over time too? At least the newer plastic ones have the reinforced flange so they'll prob last longer than original, but if I have to do this all over again in a few years, I'd rather just get the aluminum one in the first place.

[fpvsportsguy]

Just a follow up for post-mortem, I found the broken piece of plastic in the heat exchanger part of the oil filter housing. So good thing coolant was flowing that way. If it ended up in the engine block then it would be no bueno.

[Warp Ten]

Quite a project and glad you were able to find the broken part. As you noted it could have been much worse. Always better to be lucky than good. --Bob

[540iSUP]

I currently have this issue with my 2017 B58. $2400 to repair at the dealership. I usually DIY these things, but I need my car sooner than later and the dealership would have it fixed a lot faster than I would. I just replaced the expansion tank a few months ago.

[Joe-BMW33]

Originally Posted by 540iSUP

I currently have this issue with my 2017 B58. $2400 to repair at the dealership. I usually DIY these things, but I need my car sooner than later and the dealership would have it fixed a lot faster than I would. I just replaced the expansion tank a few months ago.

That actually doesn’t sound like a bad price for the dealer. I would do the same thing for the sake of time and knuckles.

[magbarn]

Originally Posted by fpvsportsguy

My 2017 530i with 120k miles just started dripping coolant pretty fast out of nowhere while parked last week. I've replaced the turbo coolant lines and the coolant reservoir return lines a couple of months ago and they still are holding just fine. I could not see where the leak was coming from top of the engine bay, even after jacking the car up, removing the underbelly panel, I still could not quite tell where it was coming from. The acoustic shield around the oil pan were all soaked and dripping, but still no obvious broken pipes/lines were in sight.

After some research, apparently this was quite common on the 330i with the B48 engines as well. The culprit was the oil filter housing, which of course is made of plastic, and one of the coolant passage gets brittle with time and would crack. See attachment, this is what mine looked like compared to a replacement. Notice right in the center, the housing is missing a big piece of the lip. The updated part had more reinforcement right around that area, indicating that BMW knew this was a problem but choose not to issue any service bulletins or extended warranties. Shame on them.

Anyways, this fix was not for the faint of the heart. It requires removing the intake manifold, which in turn requires a ton of hoses and lines to be disconnected. The manifold is held down by two easily visible e-torx bolts, 3 T30 bolts on the throttle body, and 5 very hard to see 10mm bolts buried around the wires by the intake ports.

And that's not even the hard part. The oil filter housing has 4 E10 bolts, left top and left bottom is easy, but right top is buried under even more wires and right bottom is basically blind and you have to reach around from under the car. Having a swivel E10 socket helped immensely, but these two were still the most difficult bolts I've removed in my life. At one point I was planking over the engine bay with one foot against my garage wall in order to reach.

While you're in there, chances are the engine block coolant connector (11118511205) is gonna need replacement too. It's a $10 part, just replace it so you don't have to remove the intake manifold again in the future for this job. After putting everything together, refill the coolant (about 1.5 gal in my case), start the engine and let it idle, check for leaks, top off coolant as needed. Pat yourself on the back since you just saved 3000 dollars by not going to the dealer.

One thing I'm curious about, and if anybody has experience please chime in, is the quality of aftermarket aluminum housings. I see them all over ebay for not much more than the plastic ones. Do these hold up over time too? At least the newer plastic ones have the reinforced flange so they'll prob last longer than original, but if I have to do this all over again in a few years, I'd rather just get the aluminum one in the first place.

I thought you couldn't refill the cooling system in these cars without a vacuum coolant exchanger/filler?

Is this a potential ticking time bomb? Should we be proactively replacing these at the 75,000-100,000 mile mark? I'm worried as my car is now 6 years old and just hit 70,000 miles. Seems like the N63 last revision G30's might have the last laugh, this post and the tuber videos makes this look like a serious PITA. Curse the stupid engineers who moved this to the back of the engine. The N55 had issues with leakage at the OFH, but so much easier to fix when it was at the front of the engine!

[kraymond]

I currently have this problem with mine. I changed the oil filter housing and I then noticed I have a oil leak I don’t know if the mechanic didn’t install the part correctly. Do you have any idea why this would happend

[billycal]

Originally Posted by kraymond

I currently have this problem with mine. I changed the oil filter housing and I then noticed I have a oil leak I don’t know if the mechanic didn’t install the part correctly. Do you have any idea why this would happend

I have the same issue, quite a bad oil leak as well

[kraymond]

Did you find out what was causing it ?billycal

[kraymond]

Originally Posted by billycal

I have the same issue, quite a bad oil leak as well

@billycall
Did you figure out what it was