Maintenance: Transmission Flush

[Shimmy23]

i am no expert at auto's but i have overhauled two A4ld's with good results. If you are certain that the fluid is at the correct level than i would try using the shift lever to start in first and lightly accellerate to 3k rpm than manually shift to second but back off the throttle as soon as it shifts and basically drop it into 2nd gear than use the same technique to go from 2nd to 3rd and drop it in the same way. The point is to have maximum circuit pressure at the shift point but no fwd torque on the 3rd clutch thus eliminating as much slippage as possible, and "jarring" the 3rd gear clutch and all asociated components/bands to lock 3rd up. Your staring down the barrell of a $4k rebuild, if your cautious ill bet you can get this "hickup" to fix itself. After repeated attempts if this dosent work, The 4L60E is a simple pan removal, drop it and inspect for sediment/debris. At 66k miles there will absolutely be silt adhered to the magnet but nothing chunky or gritty. it should feel like oiley dust between your fingers. unless the prior owner was running 6 bottles of trans medic in the drained fluid Ill bet your trans will resusitate itself. Hey you didnt mess with the harness that attaches to the trans in any way?

Nope didn’t touch the harness. I’ll give your suggestion a try. I’ll report back tomorrow AM

 

[Rocket Man]

Following.

 

[Shimmy23]

Tried feather the gas and working the gears manually... didn't work.

 

[thompsoj22]

Tried feather the gas and working the gears manually... didn't work.

I would drain it using the same method and use non synthetic fluid to replace. I know it is a total waste, the dex fluid you used is one of the lightest viscosity trans fluids avail. It is likely that 3rd has an issue. However i am cheap and do all my own maint so from a cost standpoint removing the new fluid is the most cost effective troubleshooting that you can do. Im guessing that you dont want to lay on your back and take a bath in auto trans fluid dropping the pan so go to wallmart and buy 13 qts of their budget brand non synthetic fluid and give a try using your method. your frustrated, retrace your footsteps. your not the first to be reminded that "no good deed go's unpunished". Ie flush the coolant and a week later the water pump/heater core starts pissing, replace the battery and the alternator fails! hang in there.

 

[SnowDrifter]

Been thinking about this. Just spitballing some ideas here. Keep the brainstorm going

1. What's in the pan?

2. Possible contamination from the process used? Or dirt infiltration from removing the lines? Not sure how the trans cooler flow is set up and the internal plumbing associated with it. Dirt intrusion blocking valves from operating appropriately?

3. Pinched o-ring or other oddity obstructing flow through the cooler. If the trans slips at all temps, that much is easy to check. Disconnect the lines at the trans and check for flow. Potentially rig up some sort of bypass

4. Does it slip in 4th? This could help you determine if it's a clutch issue or solenoid

5. How does it behave in other gears?

6. Any trans codes? Might need access to a tech 2 for this one. What are your pressures?

7. How are you checking your fluid? Hot? Cold? Running? Off? Right out of the tube or do you wipe the dipstick first? Any difference in level between the two sides of the dipstick?

8. Did you disconnect or touch ANYTHING electrical while you were doing it? Throttle body? MAF? Etc. The trans relies on some of that info IIRC

9. Try a PCM reset? Disconnect both battery cables, tie them together so the ends are touching, then hook it back up after leaving it for an hour.

10. How old is your radiator? It's possible fussing with the cooler damaged it and is causing coolant contamination in your trans fluid

11. Describe the slip condition more for me. Can you feel it shift? Does it have any "grab" at all or does it feel like it's in neutral? Throttle or temp dependent? Please be careful if you're checking any of this. Don't let it "slip" under any load, and not for more than 2 seconds. I don't want you to be in a situation where we can find the issue, only to have a clutch pack shot down in the process and now you're looking at a rebuild.

12. Not sure if synthetic is the issue here. As mentioned previous, dex6 is pretty light. It's supposed to be backwards compatible, but if it's fussy, who knows? FWIW I've used amsoil torque drive, amsoil multi vehicle atf, valvoline maxlife (the normal stuff, not high mileage), and redline d4 atf in mine. It seems to prefer the thicker stuff: Amsoil and redline over the thinner valvoline(I also have 140k on mine, parts are wearing, tolerances are larger). But even then, the valvoline never caused issues. Just shifted a little too soft for my tastes if the trans got got in traffic or something (I have a tune, shift firmness set higher). The AC Delco Dex 6 is thicker than the valvoline. And with that said, I'd think a viscosity issue wouldn't cause a hard failure like this, and only in one gear.

 

[Heyj]

Hey guys have a question for you all. Have a tahoe ppv 2012 75000. While driving when it shifts from 3rd to 4th it's like it slips in to neutral. Any suggestion.