[BeastMode335i]

I am not home and don't have my digital calipers on me, so just seeing if anybody by chance knows the size of the o-ring that goes inside the lower coolant hose that connects to the expansion tank on an E92 335i..?? I just put on my new expansion tank, and the o-ring stretched a little on the oem tank and causes a slight drip when installed on the new expansion tank.. I called BMW and they only sell the entire hose, and I am trying to avoid doing that at all cost today..

I've added a pic for reference just so you can see that I'm referring to the hose that is connected via the little zigzag line to the expansion tank lower connection.

Thanks!

[bmw335ichoppa]

I'm pretty sure it will be like a 18mm. Just take out the current one, measure it and you should be able to find some from the auto store. BMW will charge like $10 here in Australia for that. That's what i done with the lower radiator coolant hose. worked like a charm and cost me $5 for a pack of assorted o-rings

[nickb123]

Did you ever figure out the size?

After replacing my expansion tank earlier today the lower hose is a bit loose and has a slow drip. I'm wondering if it's the O-Ring...

[BeastMode335i]

I actually went to BMW and got it..

[chatch10]

Originally Posted by BeastMode335i

I actually went to BMW and got it..

What was the size or the part number?

[bbnks2]

Originally Posted by chatch10

What was the size or the part number?

I found an o-ring that worked perfectly in this oil adapter kit from advanced auto:

https://shop.advanceautoparts.com/p/...ounting+O-Ring

[BeastMode335i]

Originally Posted by chatch10

What was the size or the part number?

Don't remember, I just told them what the o-ring was, and the guy came back with it and didn't even charge me.. So, I guess free? lol..

[TheMidnightNarwhal]

Originally Posted by BeastMode335i

Don't remember, I just told them what the o-ring was, and the guy came back with it and didn't even charge me.. So, I guess free? lol..

What got something for free other than drinks and food from BMW dealer haha? Wow.

[BeastMode335i]

Originally Posted by TheMidnightNarwhal

What got something for free other than drinks and food from BMW dealer haha? Wow.

Haha yeah bro, BMW of Naples, FL is where it's at! I had a crappy customer service experience there and on my next visit to go get a keyfob for my F30 ($500+), the Manager apologized for my previous bad experience and waived the cost of the fob, so I got that for free too lol!

[ja4an]

reviving this post from the dead...I just had to do the same thing after replacing the coolant reservior tank and I bought a nitrile o-ring set from Harbor Freight. 20mm x 4mm seems to work. I'll know for sure after driving the car.

[eddieboy510]

Originally Posted by ja4an

reviving this post from the dead...I just had to do the same thing after replacing the coolant reservior tank and I bought a nitrile o-ring set from Harbor Freight. 20mm x 4mm seems to work. I'll know for sure after driving the car.

Did this work out ok for you?

[ja4an]

Originally Posted by eddieboy510

Did this work out ok for you?

yep it worked! no more coolant leaks

[steven08coupe92]

Old post but I also did this. I used the kit from https://shop.advanceautoparts.com/p/...ounting+O-Ring that bbnks2 recommended and it fit perfectly. It saves a ton of effort and money to just replace the oring, not the hose. I also have a significant drip/leak from my overflow hose at the top of the tank. Its a new FCP Euro REIN hose but after 6 months it started to leak. Inside there is a little plastic ring and a rubber oring. I bought a slightly thicker o ring from the hardware store and it seals now. I recommend having 1 or 2 on hand if you have the REIN brand hose, bc it might leak on you. Or changing it preemptively.

[Dillyyo]

Reviving this thread. I have a significant drip leak from this area where the lower hose flange mates to the expansion tank nipple. Just saw it this morning. I don't see any threads on this lower hose failing like many of the other hoses and I am hoping it isn't. Can't imagine the o-ring just failed so i am hoping the nipple end of the tank failed.

Any experiences with that hose flange failing or you think male nipple on the tank is likelier?

[northbranchroad]

Originally Posted by Dillyyo

Reviving this thread. I have a significant drip leak from this area where the lower hose flange mates to the expansion tank nipple. Just saw it this morning. I don't see any threads on this lower hose failing like many of the other hoses and I am hoping it isn't. Can't imagine the o-ring just failed so i am hoping the nipple end of the tank failed.

Any experiences with that hose flange failing or you think male nipple on the tank is likelier?

Sent you a PM. Having the same issue, any luck figuring this out? I assume the hose is cracked but it's hard to tell for sure.

[bbnks2]

Originally Posted by northbranchroad

Sent you a PM. Having the same issue, any luck figuring this out? I assume the hose is cracked but it's hard to tell for sure.

I've had to replace the oring on that hose. Picked up a generic pack of orings from AutoZone and luckily found one that was close enough to make it work. Hasn't leaked in a few years since.

[PMT_BOI]

anyone have a link to the O ring that works??
having the same problem