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Originally Posted by HPIA4v2
FSETH,
I did the ATF trans on the link provided above so I may add a few things.
My X5 had inspaection II done @30000 miles (1 or so year before I flushed the trans) and I asked dealer to do ATF flush for $250.
I doubt they dropped the pan. In any rate when I did the flush @42500 you can see how dirty it was. So my dealer probably just drained and filled back ATF w/o filter change or pan dropped.
BTW,
not sure why trans gone bad after flushing on higher mileage, but maybe the metal shaving actually clogged the valave body passages and worn out check ball actually happy in this situation. But once cleaner fluid running in valve body it may disolve the crud and makes the worn check ball stuck in valve body, check this one to see how valve body looks like:
http://www.bimmerboard.com/forums/posts/356031 |
Your dealer likely did drop the pan (can't be sure, but it would be usual) but they probably wouldn't have drained the torque converter. That means that they took out five quarts or so, leaving half of the fluid in the transmission. New fluid mixes with old, and after 10 miles or so it looks exactly like old fluid. This is one of the reasons why the value of transmission fluid changes is debated.
On higher mileage transmissions it isn't the metal shavings you have to worry about, although there could be some. If you have metal shavings, it doesn't really matter if you change the fluid or not as the transmission is likely on its way out. What wears inside a transmission are the clutch packs (multi-disk wet clutches) and the bands; both are surfaced with a non-metallic friction material that wears over time. That material is what can clog a valve body. It sits there undisturbed but can be moved by a fluid change. Clean fluid doesn't dissolve it, but draining the fluid and then starting it up and repressurizing the clutch packs can move it around. It may not happen, but in any case that is the theory behind the risks of changing fluid on high mileage transmissions.
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