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Dear Forum, My car is a 2003 BMW 530i. My coolant expansion tank has 2 hoses that clip onto it on the bottom. I assume they have rubber o rings in the coupler. Do any of you know where I could purchase them and if so what part number they would be? I just replaced the expansion tank and noticed that they seemed to leak a bit around the coupler when I connected the hoses. Once connected the leak seemed to stop but I suspect they are failing. Thanks.
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RealOEM breakout is here: 530i Cooling System Water Hoses. O-rings may only be part of hose assemblies since breakout only shows engine fitting o-rings. You might not actually have a problem if they sealed once pressurized.
Last edited by sleuth255; 02-04-2023 at 10:45 AM.
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The best place to purchase these O-rings is your local auto parts store or nearest HF. For about $10, you can buy a box of 100 O-rings of different sizes. Then use Realoem to find the size of the specific part o-ring you are interested in.
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I bought the HF assortments, inch and metric, years ago without paying much attention to the sizes they contained. SELDOM is there a useful size for automotive or anything else I work on in them. They are also poor quality, surprise, right.Originally Posted by Chedley
My recollection is BMW doesn't offer the O-rings separately. Perhaps the same size is used elsewhere and they would actually have them but they aren't cataloged regarding those hoses. They expect you to buy the assembly. Same with the sensor that plugs into the hose.
My suggestion is to measure for the size you need and buy good quality O-rings as needed.
The HF assortments I bought were a waste of money.
https://www.theoringstore.com/store/...e%20other%20ou
Last edited by ross1; 02-04-2023 at 04:06 PM.
If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue
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The issue could also be the expansion tank itself.
There are quite few brands out there and some of them are bad enough that either opening or the o rings themselves are too big or simply bad quality.
2010 BMW M6 SMG Coupe * Black Saphire Metallic * Full Leather Merino Black
2019 BMW X3 M40i * Alpine White * Mocha Leather
Former:
1997 BMW 532M (528i with 3.2 S52 engine from E36 M3 / 5 speed manual)
1998 BMW 540i 6 Speed
2003 BMW M5
Donny
I always give O rings like these a light smear of silicone grease before re-assembly. I have disconnected/reused the O ring in those quick-couplings many time with no leaking or issues.
-Donny
Dismembered
The expansion tanks don’t contain the o-rings, the hoses that plug into them do.
Set the controls for the heart of the sun
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Snotty ... welcome back!
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Hey Stephen! Yep, they once again made the mistake of letting me back….
Set the controls for the heart of the sun
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As far as I've found, there are no part numbers for the o-rings in the hoses.
The 6 cylinder cars use a 38mm x4mm (id x cross section) in the radiator hoses.
Nissen gives you spare o-rings when you buy a radiator from them... and I think
they're onto something, as I've had even 6- month old hoses leak after
disturbing them.
t
Member
Noted. This is the kind of information that ought to be assembled into a data base. Not that I'm raising my hand.
Last edited by ross1; 02-05-2023 at 03:53 PM.
If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue
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