Lower Coolant hose on Expansion Tank, O-Ring size??

BeastMode335i · 02-03-2018, 12:28 PM

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 · 02-07-2018, 12:14 AM

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 · 03-09-2019, 09:14 PM

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 · 03-15-2019, 11:47 AM

I actually went to BMW and got it..

chatch10 · 03-20-2019, 07:59 AM

Quote:

Originally Posted by BeastMode335i

I actually went to BMW and got it..

What was the size or the part number?

bbnks2 · 03-20-2019, 08:51 AM

Quote:

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 · 03-21-2019, 07:37 AM

Quote:

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 · 03-21-2019, 08:03 AM

Quote:

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 · 03-21-2019, 09:26 AM

Quote:

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 · 01-11-2023, 12:37 AM

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 · 01-28-2023, 11:37 PM

Quote:

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 · 02-13-2023, 02:17 PM

Quote:

Originally Posted by eddieboy510

Did this work out ok for you?

yep it worked! no more coolant leaks

steven08coupe92 · 03-14-2023, 01:45 PM

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 · 10-25-2023, 10:21 AM

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 · 10-31-2023, 06:47 PM

Quote:

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 · 11-01-2023, 07:21 AM

Quote:

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.

02-03-2018, 12:28 PM	#1
BeastMode335i Maximus Decimus Meridius 1129 Rep 4,584 Posts Drives: F30 335i Join Date: Apr 2014 Location: Down South iTrader: (2)	Lower Coolant hose on Expansion Tank, O-Ring size?? 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! Attached Images __________________ F30 335i Melbourne Red Metallic M-Sport Package
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02-07-2018, 12:14 AM	#2
bmw335ichoppa Registered 1 Rep 4 Posts Drives: 2010 BMW E90 335i LCI Join Date: Feb 2018 Location: Sydney, Australia iTrader: (0)	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
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03-09-2019, 09:14 PM	#3
nickb123 Registered 4 Rep 4 Posts Drives: 2011 335i Cab Join Date: Mar 2019 Location: Toronto iTrader: (0)	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...
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03-15-2019, 11:47 AM	#4
BeastMode335i Maximus Decimus Meridius 1129 Rep 4,584 Posts Drives: F30 335i Join Date: Apr 2014 Location: Down South iTrader: (2)	I actually went to BMW and got it.. __________________ F30 335i Melbourne Red Metallic M-Sport Package
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01-11-2023, 12:37 AM	#10
ja4an New Member 9 Rep 24 Posts Drives: 2011 x3 xDrive35i Join Date: Aug 2018 Location: Bay Area, CA iTrader: (0)	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.
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03-14-2023, 01:45 PM	#13
steven08coupe92 New Member 6 Rep 17 Posts Drives: 08' BMW e92 328xi 6mt Join Date: Mar 2022 Location: Tucson Arizona iTrader: (0)	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.
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10-25-2023, 10:21 AM	#14
Dillyyo New Member 2 Rep 19 Posts Drives: 2011 BMW E93 N55 LCI Join Date: Dec 2022 Location: NJ iTrader: (0)	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?
	Appreciate 0 Quote