[OG Style]

I have a coolant leak on a hose. I think its the o ring and I'm having trouble finding a part number. I attached a picture of the line. 2011 328xi.

Thank you

[jadams161]

Realoem.com

although I don't think you can buy the orings thru BMW. I bought an entire o-ring kit for the N51/52 from AliExpress

[Serf27]

Yes, you need an o ring kit to replace it.
Unless the upper hose is worn down.

[ppointer]

+1 on realoem.com. My go-to resource for part numbers.

[OG Style]

I just talked to BMW parts department and they think I need a new hose. Around $75. I will check realoem.

[gbalthrop]

Originally Posted by OG Style

I just talked to BMW parts department and they think I need a new hose. Around $75. I will check realoem.

That's the place to START. I think you will find the BMW Part# is 17127531579
https://www.realoem.com/bmw/enUS/sho...diagId=17_0350

Inserting that part# in Autohaus, ECS & Amazon site search boxes yields:
https://www.autohausaz.com/pn/17127531579
https://www.ecstuning.com/BMW-E91-32...h/17127531579/
https://www.amazon.com/s?k=BMW+17127...f=nb_sb_noss_1

I would be VERY CAREFUL HOW you remove the Upper Radiator Hose from the Radiator. Plastic that is 16 years-old, and has been through several thousand heat cycles is VERY BRITTLE. A cracked radiator will greatly increase your time & expense.

ANYONE who has successfully separated those fittings, please offer specific tips. I have NOT, but my understanding is that you do NOT Twist the fitting, as there is a locating notch.
George

[OG Style]

I think the leak is coming from the hose that runs vertically. I didn't see the vertical hose on realoem.

[Nando_e90]

Originally Posted by gbalthrop

ANYONE who has successfully separated those fittings, please offer specific tips. I have NOT, but my understanding is that you do NOT Twist the fitting, as there is a locating notch.
George

I've used a heat gun to heat up a bit the hose fitting and it has worked. That upper hose is easier to remove than the lower one.

[jsunma]

Originally Posted by gbalthrop

That's the place to START. I think you will find the BMW Part# is 17127531579
https://www.realoem.com/bmw/enUS/sho...diagId=17_0350

Inserting that part# in Autohaus, ECS & Amazon site search boxes yields:
https://www.autohausaz.com/pn/17127531579
https://www.ecstuning.com/BMW-E91-32...h/17127531579/
https://www.amazon.com/s?k=BMW+17127...f=nb_sb_noss_1

I would be VERY CAREFUL HOW you remove the Upper Radiator Hose from the Radiator. Plastic that is 16 years-old, and has been through several thousand heat cycles is VERY BRITTLE. A cracked radiator will greatly increase your time & expense.

ANYONE who has successfully separated those fittings, please offer specific tips. I have NOT, but my understanding is that you do NOT Twist the fitting, as there is a locating notch.
George

So yeah, I've done this hose and George is correct. The number one failure point for the radiator is that upper mount, which is very easy to crack when you remove the hose. But removing the hose is likely what you will need to do since that particular hose's fitting also has a tendency to break where the overflow tube (the one that runs from the overflow tank across the top of the radiator to that fitting in your picture) connects to the fitting.

All I can recommend is to be gentle and go slow removing it. Try NOT to leaver it with a screw driver or something that would be likely to put pressure on the radiator fitting and crack it.

I have heard that a bit of heat helps, but again, be careful because everything there is plastic.

Ideally, you'll pop off that metal clip, and the fitting will pull off the radiator with just a little tug. Pull as straight back as possible...no twisting.

[jsunma]

Originally Posted by OG Style

I think the leak is coming from the hose that runs vertically. I didn't see the vertical hose on realoem.

That vertical hose is one of the two that connect to the heater core. I believe the one you're asking about specifically is:

https://www.ecstuning.com/Search/Sit...h/64219178427/

It actually costs more than the radiator hose (for which the $25 Rein hose is fine...no real need to spend 3 times more for the BMW-labeled one, IMO).

I'd suggest getting the radiator hose and trying that first. It's an easy fix assuming nothing breaks. In my case, I bought the heater hose too, but never installed it as replacing the radiator hose fixed my issue, and I would just as well not have to bother with the heater hose unless necessary (the EASY end of that is the front end...getting to the end at the firewall requires more work).

BTW, I'd suggest FCP as the parts source if you're intending to keep the car for any significant length of time. Their lifetime guarantee is great for stuff that you KNOW you'll be replacing more than once...such as coolant hoses and radiators.

[jsunma]

One last thing. The more I look at your photo, the more I suspect that it could just be the o-ring inside of that fitting on the heater hose. If so, and you have another car to get yourself to the autoparts store (or even a good sized hardware store), you might pop that off, remove the o-ring and go get it sized up properly and buy a new one. That would be much preferable to spending $45 bucks on the hose (which has the o-rings in it) and digging out the far end of the heater hose at the firewall.

From what I can tell (recall that I have this hose uninstalled, so I just went and looked at mine), the o-ring in question is quite possibly a 22 X 4mm. But I have a 22 X 4 and it seems a hair too big around...so perhaps there's such a thing as a 21 X 4. Anyway, I'd remove the old one and compare it with what's available at the hardware or autoparts store.

Good luck!

[Serf27]

Spray some penetrating oil around the fittings once you remove the clip and let it sit for a few minutes.
Hoses come off much easier.

[OG Style]

I've tried looking for the orings locally before and I had no luck. Thanks for the measurements. I will try looking again. BMW doesn't sell the orings. The radiator hose looks like it might have been replaced before. If I can't find an original I will replace the radiator hose first. The leak isn't real bad but it makes me worry when I drive out of town.

[OG Style]

Something I noticed is that it's leaking around the retaining clip. Is there an oring in the radiator hose or is it in the vertical hose?

[Serf27]

O ring is in the smaller vertical hose.

[mainbearing]

There are o-rings in the upper radiator hose large connectors too. The o-rings are the primary seals, and proved to be less reliable than a plain rubber hose end with a hose clamp. The factory hose connector (including the Mickey flange) obviously is made of a cheap plastic than what is on the radiator.

I also have a Gates upper hose on there now. The old one I cut with a Dremel to help protect the radiator, after hearing all the cracked radiator stories. The Gates upper hose does carry lifetime warranty. A heat gun seems to be the best "non-destructive" method of removal.

My Gates upper hose:

The old factory hose cut, as well as a failed Mickey flange upon removal:


You can use this search function. 4 mm CS o-rings are usually huge, like 100 mm ID. So I played with smaller CS like 2.65 mm. You can adjust the numbers and see:

2.62mm CS x 15.88 ID, FKM is Viton, like the new OFHG from Japan:
https://www.marcorubber.com/store?se...15.88&offset=1

Metric o-ring size chart:
https://www.marcorubber.com/o-ring-s...art-metric.htm

From BMW of Silver Spring's catalog using jsunma's part number. It is quicker just to get a hose in case you cannot find the correct o-ring and still waited for shipping.

[gbalthrop]

Originally Posted by OG Style

Something I noticed is that it's leaking around the retaining clip. Is there an oring in the radiator hose or is it in the vertical hose?

O-rings, whether in Refrigeration fittings, Plumbing fittings, automotive fittngs, usually leak at SOME point. Rather than "run to the store" for "THE correct O-ring" when an emergency arises (wasted time, gas, aggravation) I bought TWO O-ring kits years ago, and have used a dozen+ times.

HNBR, Nitrile, Buna-N, Other(?) compounds are available. It is my understanding that HNBR (usually green) is best for refrigeration systems.
ANYONE have knowledge of type of "Rubber Compound" that is best for a particular use? I have simply used "Imported" supplies from HFT & Amazon, with NO issues in any application from R-134a refrigeration fittings to plumbing

Here are some examples:
https://www.amazon.com/s?k=o-ring+ki...31&ref=sr_pg_1
George

[rt7085]

I always struggle with that question as well. Time to do some reading and googling. For now my simple rule is: You touch an old hose, you replace that old hose. Which is what I am doing today when I replace my water pump and thermostat at 142k. (So, I am doing alright from what I read...)

[OG Style]

I will probably try ordering both the hoses so I have them on hand. I would rather to only replace the radiator hose but it sounds like the oring in either one could be the problem.

[OG Style]

I'm looking a the radiator hose and I can't find the oring on it where it connects to the other hose. Is there 1 oring or 2?

[Serf27]

1 o ring on each connection that has a C-clip
Radiator hose has 2 clips, so 2 rings, 1 at radiator connection and 1 at oil filter housing connection.

Line going up to radiator hose has 1. They’re in a groove in the hoses.

[OG Style]

Thats what I thought. The leak can only be coming from the oring in the vertical hose.