leaking new expansion tank
 

just installed a new coolant reservoir expansion tank on my 3.0 and im getting a leak at the small nipple near the cap. i already have a replacement but i just want to make sure im not doing something wrong. after i installed the new tank, i lifted both clips and just snapped it on the tank but i noticed that the larger one that attaches to the radiator was hard to get on and the smaller fitting just snapped onto the tank real easy.

Depending on the brand but if its oem it could be defective and if its aftermarket try to return it and get the oem one from the dealer or rock auto. Found one for my x5 on rock auto for $40 brand hella (same as behr, oem quality)


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I looked at my m54 expansion tank and I do not see a nipple hear the cap... Do you mean on the actual cap? If it is leaking at one of the hoses just replace the oring in the hose and lube it with some silicone grease and throw it back on. Not replacing orings usually causes leaks.

where could I find an o-ring that would fit? home depot?

I circled where it's leaking from so u know I'm not talking about the actual cap

You are leaking from the oring is my guess. They get smoothed over after awhile. I am not sure what size it is, if you go over to e46fanatics and search their you will probably find a few threads about that.

We have oring shops here that sell things like that and maybe you have one too. The only thing is they will not sell you just one, usually you have to buy a like 10 or 20.

My Nissen radiator I replaced on my e46 came with a spare oring for that hose. I would contact them and ask them what size it is and maybe they can help you source one.

I would recommend pulling the old seal out, measuring it (inside and outside dia) and replacing it. The seal more than likely is pinched/cut during dis-assembly. If your lucky it will be the same as many hose or A/C seals and be available over the counter at your local auto parts distributor/store. Going into to an big box auto parts store will not get you what you are looking for as no one there will have a clue on misc small parts like this.

Any BMW dealer can get you matched up if the counterman/girl knows the misc section. There is no part number listed when that seal is included with the hose.

Found the assortment package (there are lots of other sources) ECS O Rings ES#2938443 Metric O Ring Assortment
http://www.ecstuning.com/b-atd-tools...t/atd3601~atd/

just installed the new tank and its leaking from the same place so now I'm thinking it's the rubber o-ring inside that could be the problem

Get this stuff - temporary assembly lubricant Seal O-Ring Rubber etc. This is a must have for any DIY mechanic. It critically eases the installation of components with seals etc and thereby preventing them being crashed/cut during application of force while installing the component. It's also used to install bushings with ease. It works miracles. You can use it to install even stuff without rubber and it just makes things significantly easy - they just slide through. I use it all the time and saves me time, effort and tears (literally). You just apply it sparingly and that single tube will last over many, many applications.

P-80 Emulsion Temporary Assembly Lubricant Seal O-Ring Rubber Assembly Aid | eBay

P-80® Emulsion Temporary Assembly Lubricant is a biodegradable assembly aide that eases installation of tight-fitting rubber and plastic parts by reducing the force needed for insertion. Once assembly is complete, the lubricant dries and the part returns to its original condition. P-80 Temporary Assembly Lubricants can be applied manually or automatically, by dip, brush, or spray techniques.
P-80 Emulsion Temporary Assembly Lubricant is used to install hoses, o-rings, seals, bushings, gaskets, grommets, grips, and many other rubber and plastic parts. Use P-80 Emulsion when a thin film of lubricant is desired.

i didnt have a problem with it being too tight, the problem is that it isnt making a tight seal. it actually comes on and off way easier than all the others