New expansion tank..still leaking.

[takumidrift30]

On my 525i, had a leak at the bottom of my expansion tank before, so change the whole tank with new o-rings and new seal did it exactly the way as DaveVoorhis described in his thread. I actually pulled the whole radiator down to clean the radaitor and front section of the engine bay. Put it back put coolant, started the engine rev at 3500 rpm, bleed, let it runnig at idle for couple of minutes and no leak.
This morning as I was about to go to work saw it again leaking on the same spot. I cleaned the radiator and the area for the expansion tank very thoroughly made sure there's no gump or any form of debri on tank section. When I installed it used a rubber mallet to make sure it was properly fitted.
What should I do to next? Thanks in advance.

[DaveVoorhis]

Did you lube the tank o-ring with antifreeze before hammering it in? You sure it's leaking around the expansion tank and not from the radiator endpiece that the tank fits into?

Are you sure the endpiece isn't cracked? Sure it isn't a leak in the rad core near the tank? If it's either of these, put in a new radiator. It's not worth fixing, and worth the cost of a new rad not to have to think about it for the next decade or so.

[takumidrift30]

Did you lube the tank o-ring with antifreeze before hammering it in? You sure it's leaking around the expansion tank and not from the radiator endpiece that the tank fits into?

Are you sure the endpiece isn't cracked? Sure it isn't a leak in the rad core near the tank? If it's either of these, put in a new radiator. It's not worth fixing, and worth the cost of a new rad not to have to think about it for the next decade or so.

Got an update Dave, it's now leaking on the housing of the bleed screw. Guess at this point I don't have any choice but to put a new radiator. Does a new radiator comes with a new expansion tank?

[winfred]

yes

ps don't get the CSF (cooling systems and flex) brand they suck


Does a new radiator comes with a new expansion tank?

[mzarifkar]

Ive had a similar problem, here is what i did http://www.bimmer.info/forum/showthread.php?t=29573

[takumidrift30]

Ive had a similar problem, here is what i did http://www.bimmer.info/forum/showthread.php?t=29573

Mzarifkar I actually ran into your thread also as I was doing my search on how to fix it, mine didn't have any goops or grime on it, and before I installed it back cleaned everything very thoroughly, guess as Dave had mentioned it's the housing for the tank leaking itself.
Winfred thanks! I bought Behr.