Wrong Trans Fluid Slipping after flush

mmikeman

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Hey folks, got a 2006 Pontiac Montana when first got the van noticed trans fluid was burnt and somewhat brown, left it for 15,000miles didn't have any issues, decided to do a filter change pan drop the other day about one day after doing this procedure 1st gear began engaging slowly when vehicle was cold only....van would rev but not move fast unless started in 2nd gear, figured I was SOL but then noticed I had refilled the 4t65E trans with Dextron 3 instead of the new Dextron 6 the dipstick and manual call for (my older Pontiacs take 3 and have the same trans), after driving it for a few days contaminated I disconnected the return line and flushed the fluid again and refilled with Dextron 6, now it seems to be a little better but problem still exists, once it warms up no issues at all, do you think using the dex 3 really caused all of this? Or maybe this is just bad luck from doing the flush and something clogged up somewhere. Do you think I need to use a machine at this point to completely flush everything out or would me flushing and refilling be enough for now
 

melsg5

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Dexron 6 is thinner than 3 so doubt that is your issue.
When you say flushed, do you really mean disconnected a line and drained?
I would consider the Transgo shift kit for your issue.
 

mmikeman

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First time I changed it when fluid was burnt brown, I dropped the pan changed the filter and added 7.2 quarts of the dex 3, second time I disconnected the return line ran engine for 20 secs which lost another 7 quarts then added dex 6 back into the system again, now I essentially have 60% of dex 6 new fluid and a mix of dex3/6 for the old stuff that didn't drain, shift kit sounds like a good idea too, I talked to a trans guy he seems to think my forward band is on its way out so the goal for now would be raising the pressure as well however I dont think I can do that without a shift kit unless they sell a tuner for these vans
 

melsg5

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Look at the instructions at the Transgo site to see if it is something you want to attempt.
______________________________
 

mmikeman

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Added a cold air intake this weekend, of course now I have the slip clunk while engaging in drive a lot but it doesn't do it when starting in 1st and shifting manually, would shift kit still help this or is there something such as a tuner than could up the pressure in the 4t65E? I am suspecting worn clutches but I could be wrong
 

melsg5

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That is what the shift kit does, look at the Transgo site.
You seem to be still driving it increasing the chances of needing to overhaul/replace the transmission.
The shift kit should have been the priority over the CAI.
 

cammerjeff

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Belleville MI
Yes the shift kit will increase the line pressure and make the shift "crisper" usually the kit will have instructions for 3 different tunes. I would not use the most aggressive tune for a street driven car, but even the least aggressive tune will firm up the shifts, and you can also usually adjust the rpm the trans shifts at by swapping out springs. We did it to our old 99 Grand Prix GTP and it worked wonders on eliminating slippage when shifting.

If you have already had the pan off, the shift kit is not that much more complicated. It usually even comes with the drill bits to use on the shift plate under the valve body.

good luck
 
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