What I'm saying is that yours just didn't fail yet. It's great if one can catch this issue before it fails because it's so simple to prevent it from happening. The o-ring will never come out of its seat until there is enough room for it to do so. You didn't see It because yours didn't fail. Sadly I didn't take a pic from the best angle to show why I'm absolutely certain that regardless of other valid email examples of what can help the problem along, that without the tilting of the seat of the o-ring this o-ring failure would be non-existent.

It's best if somebody can catch it before it failed because then fish a zip tie though without even disassembly and you are done. For a non-pro I wouldn't even recommend messing with the other "seal" that will only drip when it fails.

Simple engineering and geometry plus laws of physics dictate why I'm making my claims. There is a 1" cross section with 18psi pushing down about 1" from the fulcrum. 18 in · lb of torque applied to a plastic part for 4000 hours is apparently enough to bend it enough to get the o-ring close to where it will squeeze out of the seat.

Very possibly a toward the thinner side of spec on the o-ring cs or fatter opening on the plastic part or a spike in pressure will be a contributor to the failure it's rarely just one thing. My contention is that in spite of any of the other contributor factors it will simply not ever fail if the o-ring seat is always square.

You could overcome the problem with a fatter o-ring but it's unnecessary since the primary issue is the not square seat of the o-ring.

The fatter o-ring fit makes a lot of sense and you are more correct than it sounded like I was suggesting only it was not the o-ring that shunk it was the plastic that grew: case in point the other non-seal "seal". I measured that the outer part was a full 0.2mm larger than the inner part and that is without the intense pressure of an o-ring pushing on it for 17 years in my case. I am willing to bet the outer part has grown at least half a mm making a chubbier oring make more sense than the OE spec that will work just fine in my opinion, the fatter cs option will work fine-er.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)