[OG Style]

I think its fixed. It was the radiator hose. It was running down the back side into the other fitting. I didn't replace the vertical hose. I only used the o ring out of it.

[StradaRedlands]

Originally Posted by OG Style

I think its fixed. It was the radiator hose. It was running down the back side into the other fitting. I didn't replace the vertical hose. I only used the o ring out of it.

Good job getting apart without causing more damage... that's the trick!!!

[OG Style]

I did it cautiously. I actually cut the old radiator hose in have then removed each half separately. I knew I was replacing it and had no reason to try to save the old one.

Thanks for all the help.

[bimmbo]

Had a similar problem after replacing my radiator, radiator hoses and expansion tank and hose. Prior to replacing everything, I had a coolant leak that I thought was coming from the top of the radiator so I ended up just buying all this hardware as I've heard it's a pain to get the hoses and such off in one piece. While pinpointing the leak, after removing my intake manifold I could see the expansion tank hose running along the top of the radiator spraying out liquid. So I thought I could just replace that and hold on to the other hardware until I knew they'd need to be replaced. I tried to remove the hose from the upper radiator hose and it immediately snapped right off with little force. Ok, fine, so now I needed to replace the upper radiator hose. Started tugging on the connection at the radiator and boom, snapped the fitting off the radiator, doh. Guess I was going to have to replace the radiator today after all. Glad I bought the all aluminum CSF radiator so this hopefully doesn't happen again while I own this car. After putting in all the hardware and refilling with a flush kit and distilled water, found a leak at the upper radiator hose. It was coming from the vertical hose connection and everytime I'd flex the hose, liquid would gush out of the vertical hose end. I looked at the hose and fitting and saw no signs of damage, but the o-ring definitely looked compression set and no longer making contact with the upper radiator hose vertical fitting. I measured the new Rein hose's vertical fitting and it was about .016" (I know, shouldn't be working in inches but it comes in handy later) smaller than the old Contitech I pulled off. Used o-ring had an ID of .879" which was larger than the .865" new hose fitting. Went hunting for o-rings on McMaster-Carr and couldn't find the right metric size (I think 21.5 or 22 mm ID x 3.6mm) in a suitable compound that would cover the temp range, so went with a .859" ID x .139" CS in Viton 75 Duro, good from -15 to 400 deg F (I'm in CA so not that cold but I know Viton still works below the -15 deg F rating anyways). I got a 5 pack for $6. Shipping ran me another $10. Hope to get the part tomorrow and give it a whirl. Will update then...

Update: o-ring is holding fine, no leaks after 20 minutes drive. Hose felt a bit tight to install after putting the new o-ring with light film of Dow vacuum grease. My guess is it's fine since the new upper radiator hose lower connection was slightly smaller OD than previous but I think stock o-ring is actually 22mm ID x 29mm OD if anyone's wondering.

[KevinAnLipscomb]

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

For me, the trick was applying heat to the connection (with a heat gun) before implementing a very sophisticated wiggling process.

[thecos]

Just confirming that the McMaster o ring mentioned above is the same one used in the hose that connects to the bottom of the expansion tank. The original is 22mm id x 29mm od (3.5mm thick). McMaster also sells the metric version but the 7/8” id 1-1/8” od ring is very close in size and working just fine.

https://www.mcmaster.com/product/1288N172

[1st time BMW owner]

Speaking about upper radiator hose removal, I've a 2009 328i coupe and I replaced all hoses about a year ago. That upper hose connection port on the original radiator broke when attempting to pull the hose off, moving it up and down slightly while pulling the hose straight off. No "twisting" motion was applied. The point where hose connection port meets the radiator tank, where it fractured, was only .010/.012 inch thick where thinnest. Apparently, coolant turbulence around the bend area had, over 16 years and 120,000+ miles of service, worn the area so thin just a little force broke it off. I am 2nd owner, the original owner did all recommended maintenance at the dealership, and coolant system is very clean. It is an "Super Ultra Low Emissions" car, the replacement radiator with special coating and sensor for the emissions, was over $600 US for this car and took days to arrive. My hose replacement job got very expensive, even though I do all my own work, saving labor costs. Given the thinned plastic, i really doubt anyone could have avoided breaking mine when removing the upper hose. Regardless, BE EXTRA CAREFUL AS THE OLD PLASTIC IS BRITTLE. LUBE THE HOSE WELL BEFORE REMOVAL!
Hopefully, my bad experience will help people realize the extra care required with plastic parts, even then mishaps are sometimes unavoidable, so be forewarned, and good luck.

[OG Style]

I haven't broken any plastic yet. Since this post I've had to replace two more lines. One going directly to the water pump. It takes patience getting them off. The plastic degrades over time and the heat cycles doesn't help any.