I've got a transmission that seems to shift fine until it hit 3rd, then it slips.   When I bought the car it slipped in most gears, I drained the oil twice thinking they may of mixed the wrong oil in from the diff.  After the second time it is much better but still slips as mentioned. 

 

So, drain and fill again or take it to a tranny shop to see if the can figure out if she's shot or if it is just a solenoid.

 

Comments,suggestions?

 

Thanks

Change again. Only a small percent of fluid comes out of an AT with a drain.

 

Is the AT pan dented or damaged?

 

Read the AT trouble codes and engine codes. Anything?

 

Describe the slipping.

 

You can disconnect the TCU and run it in purely mechanical mode which is 3rd gear. If it slips then that may give suspicion that it's a mechanical failure. I'm not sure if internal solenoid failures or others could still bleed off or cause issue indknt know the fluid flow or hydraulic functioning of the trans.

I will change again.   Pan is not dented.   I will check for codes.  It will shift fine as mentioned and then when goes to 3rd, it will shift but will slip, tach revs and the trans is not moving the car forward.  I will try the TCU as mentioned.

 

Thanks for the quick response.

3 drain/fills gets you about 85% new fluid. If that has helped already, you could try it again. Most folks like Valvoline MaxLife in the 4EATs.

 

some folks that continue to have delayed engagement or other issue have reported that a bottle of Trans-X  (K&W or CRC brand ?) helps.

I didn' t do another drain and fill yet but here is what I have for codes - P0733, P0734- Gear 3 and Gear 4 incorrect ratio.

 

I disconnected the TCU and the trans was stuck in 3rd as mentioned and the car went down the road fine - a little sluggish at the start - a bit of slipping. Easy on the gas and it was fine.

They drive funny like that only in 3rd gear - slow to accelerate and different feel.  So some of that is normal.  Does it feel like it's slipping exactly the same as before or less or different or more?

 

Those aren't good codes, doesn't look like something as simple as a solenoid. I'm not well versed in transmissions but I'd be thinking mechanical failure, a used transmission would be one easy and least expensive option:

www.car-part.com

 

if you wanted to diagnose I think you'd check solenoid resistance and maybe pull the pan/check the internal filter/magnet for debris or metal. 

You could replace the screw on external filter as well - although they're pricey and not likely to be the cause.

 

But I have no idea - maybe it's something else or maybe they can run indefinitely like this if the thing is at all driveable. 

I drove(TCU disconnected) it around my area without issue where before it would go into 3rd and just slip.