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E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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Old 04-23-2012, 07:28 PM
bigblueoval bigblueoval is offline
Location: Statesboro Ga
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Mein Auto: 325i
Expansion Tank Replacement

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Ok, so I changed the expansion tank...upon crank up, it it leaking like crazy up top. There are 2 fittings on the top hose going to the motor..one goes to radiator, other small one goes to expansion tank. The snap ring is in good..I took it off several times and reinstalled it. QUESTION..Is there supposed to be an Oring inside the piece on the radiator hose that slide up over the small male fitting on the tank? Thats the only reason I can figure its leaking.


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Old 04-23-2012, 08:26 PM
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RSPDiver RSPDiver is offline
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Hmm... If I recall the part I think you're talking about, then I think there is. But you might want to PM Smolck and/or add some pics to your question. Smolck has probably seen as many E46 cooling system refreshes as any BMW tech on any floor (read: not saying the service mangers) of any BMW stealership around. And he gives a rip, or he wouldn't be so active on here and in his community for DIY and maintenance support.
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Old 04-23-2012, 09:20 PM
alpinweiss alpinweiss is offline
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Yes, there should be an O-ring inside each hose end. If the O-ring is missing (or displaced), it would leak like crazy.

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Old 04-24-2012, 06:42 AM
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J. Kidd J. Kidd is offline
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Make SURE it is pressed in tightly. I've done this twice and both times it initially leaked on me even though the snap ring was able to be pushed down and everything appeared to be nice and snug. Turns out I just needed to push it in a bit further. Once I did (it took a bit more effort), the snap ring was able to go down again and everything was fine. The difference can be 1/16-1/8" - that's all it takes. Good luck.
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