Air in Tranny

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This has not happened to me but I am curious about the consequences of running the tranny dry momentarily while using the tranny pump to remove old fluid from a disconnected cooler supply line. I always pump out a couple quarts, stop engine, add back same amount of fresh fluid and continue until done. If, by accident, I pumped until no more came out, would the tranny pump suck air and do permanent damage? My understanding is nothing bad will happen providing you promptly stop engine. Any air that may be picked up by the pump running dry will quickly self-purge. Thanks.
 
No problem. I run them until i just see an air bubble or two then shut it off.
When you see air bubbles at the end of the line there is still some oil in the pump. It self primes.
 
Rather than disconnect a line and use the pump just to drain, disconnect a line that feeds the ump and fill it up at the same time
wink.gif
 
Originally Posted By: Trav
No problem. I run them until i just see an air bubble or two then shut it off.
When you see air bubbles at the end of the line there is still some oil in the pump. It self primes.


That is my understanding and it makes perfect sense from a hydraulic perspective. Some knucklehead on another forum is arguing that getting air in the system will cause damage. I believe that is utter nonsense as the tranny pump is self-priming and the hydraulic circuits are self-purging.
 
Originally Posted By: artbuc
the tranny pump is self-priming and the hydraulic circuits are self-purging.

They are. Letting it run dry then continuing to run the engine could damage the pump because it runs out of fluid but as long as your still getting some fluid even with some bubbles in it, it isn't a problem.
I never lost one doing it this way. And that started with 2 spd power glides over 40 years ago.
 
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