Which way does the tranny fluid flow through the lines?

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Nov 29, 2001 | 09:32 PM
  #1  
What I want to do is flush out the tranny fluid the easy way. I changed the fluid and filter about 1000 miles ago, but I had type F in the tranny before and I want to go back to dexron. Since I only got about 1/2 the type F out, I wanted to flush the rest out. I thougth instead of pulling the pan and making a mess I could unhook one of the lines at the radiator to the tranny cooler and let the fluid be pumped out that way while I added it back through the fill tube. But which line, the lower or upper, does the fluid flow from the tranny to the cooler? Meaning, which line should I unhook?

Also, if anyone has reason to believe that this is a bad idea or that I could hurt the tranny in some way, speak now!

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91 Z28
Come see The Vicious...
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Nov 29, 2001 | 10:47 PM
  #2  
It's the upper hose. Just make sure no to run it too long. It may take quite a while for all the type f to get out of the system.
SSC

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85 Camaro Z28, Cowl induction hood, Black-355/TB400,3:42 posi, Tons of goodies but if you ask, "Its stock"
82 Firebird, White, red in six months-355/TB350,3:42 Powertrax posi. Not an insane amount of goodies but it runs like a motha!
76 Chevy C10, Firemist blue, 355/Muncie HD 3speed,3:73 TorqLine posi. Show me another 12sec@4800ft SBC street truck??
91 GMC 1500 Sierra 4x4, Red, Was 4.3 now the proud recipient of the Firebirds LG4. 305/5 speed.
56 Buick Special, OG Blue&White, V8/auto. Maybee one day I'll get it going.
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Nov 29, 2001 | 10:47 PM
  #3  
From the tranny the fluid flows first into the lower part of the radiator. I know this because I asked same ? when installing a cooler.
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Nov 29, 2001 | 11:41 PM
  #4  
Most TH700R4s that I have seen have the feed to the cooler as the lower pipe and the return as the upper pipe.... I just glanced at my Tech Guide and it shows the feed for the cooler being the lower pipe as well....

EDIT: As far as whether or not to do this goes; I have seen this procedure done quite a few times and it works fairly well. A lot of shops have machines that will do this procedure as well. As suggested, make sure not to run it dry and have a much more than adequate container for the old fluid.....

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

[This message has been edited by Matt87GTA (edited November 29, 2001).]
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