How Do you Purge Air Bubbles Out of ATF?

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Apr 4, 2009
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Ontario, Canada
I've been reading on the AT Oil Cooler method ATF replacement technique, as opposed to the regular drain & refill method - but what I've come across is some people introducing air bubbles into the system and causing some problems. I don't know if it's because they idled the car for too long when the old dirty oil leaves the cooler, and the reservoir in the tranny get's empty? What causes this - and is there a way to avoid it or at least purge the air or suspected air once the procedure is complete...as a safety measure.
 
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I never had this problem. 1 litre out 1 litre in. Or drop 1 line into discharge bucket and the other line into the new bottle of ATF. I know you can have air pockets in cooling system but never heard of it in AT.
 
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It sounds like you might have read about people who've ran the transmission dry by having the transmission pump out too much fluid at a time. You suppose to only pump out half of the capacity of the pan at a time and replace the fluid and do it again until you see clean fluid coming out. When I did mine I had 4 quarts of fluid in the pan and started the car for 15-20 seconds at a time and was able to get out 1.5-2 quarts each time.
 

1993_VG30E_GXE

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Hey dudes, here's where I read it: http://www.cardomain.com/ride/748507/24 And I've heard other guys talk about it on a Maxima (the ORG) forum that I read all the time. He says what you say to, to do 1 L at a time, and it shouldn't happen. ANd guys, the method where you the first hose goes into the discharge bucket, then you put the new fluid in the reservoir OR you said feed it through the return hose - is there a risk of running the trans dry, or not with your 1 L amount - it would never risk running dry? Also does the return line feed into the same chamber as the dipstick tube - so it doesn't make a difference if you use one over the other?
 
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kansastan
I've only used the bucket-flush method once. I just overfilled the transmission by 6 quarts, then pumped 6 quarts out. Worked great.
 
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I personally flushed over 100 Nissans via the cooler line without ever get any issue with 'air'. I've always let them run 'til the cooler hose burped air. Its sounds to me that some of they backyard yahoos don't have a clue. You can not feed ATF through the return tube. Shut 'er off and top off completely via the dipstick tube. Learn to measure amounts removed so that you can add that amount back. And, don't go answer the phone without shutting it down. Skips the beer until your finished.
 

PT1

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 Originally Posted By: unDummy
And, don't go answer the phone without shutting it down. Skips the beer until your finished.
Just wondering if there is a good story attached to the "phone" and "beer" warning.....
 
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PT1, too many good stories. From neighbors coating their driveway with ATF, to friends driving away while I look at the metal thing(drainplug) in their driveway wondering if its a spare, a blown headgasket during a coolant flush(diligent husband answering wifes phone call), wheels falling off after a rotation.........and plenty of flying tools(occasional digits too) from encounters with moving pulleys/belts
 
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 Originally Posted By: aaxb970
I never had this problem. 1 litre out 1 litre in. Or drop 1 line into discharge bucket and the other line into the new bottle of ATF. I know you can have air pockets in cooling system but never heard of it in AT.
The return cooler line to the transmission drain pan has zero suction. I doubt it ever worked dropping a cooler line into a new bottle of ATF.
 
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If you drain via the cooler line until you see air bubbles in the clear tubing. Almost nothing is rotating in the transmission when its in park so a few air bubbles are no problem.
 
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