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Old 01-08-2013, 12:26 PM   #21
WDE46
Registered User
 
Join Date: Sep 2012
Location: Old Greg's Cavern
Posts: 8,952
My Ride: 2004 330Ci OBM
Quote:
Originally Posted by ///MPR77 View Post
Why do these things have such a weird, spread out failure rate?
Aside from the O Ring, why do these fail for some, and last longer for others.

Here is my old one.

I pulled this out at 293k miles.
Replaced it with a new one, but I feel like the old one was fine.
It might come down to the dimensional tolerences of the injection molded parts. Here's a couple scenarios with possible outcomes:

Scenario 1:
The square yellow piece is in the upper range of it's size tolerence.
the flap's square hole is on the lower range of it's size tolerance.

This scenario creates a tight fit which may prevent the flap from ever jiggling and wearing down the inner surface of the flap/outer surface of the yellow arm

Scenario 2:
The square yellow piece is in the lower range of it's size tolerance (bordering on too small)
The flap's square hole is in the higer range of it's size tolerance (almost too big)

This scenario creates a situation in which there may be a small amount of play b/w the yellow piece and the flap, and the parts experience increased wear. The play will increase over time which will continue to increase the wear.


It could also come down to driving habits, but I think the above is possible.

Last edited by WDE46; 01-08-2013 at 12:28 PM.
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