Transmission Qwirkyness

[ptcfast2]

98 3.1L

My transmission has 224,000 miles on it. It's been serviced regularly and has not really had any problems until the past 3,000 miles or so. It's starting to have a rough time down-shifting (3rd --> 2nd shakes the car at times) and has a noticeable "clunk" at times when shifting up from 1st --> 2nd. These symptoms normally occur when the transmission has warmed up and had had to do a full shift through multiple gears a few times in a row (hitting stop lights about 2 miles apart for example).

The fluid itself was last changed at around the 215,000 mark. I added Auto-RX to the fluid about 1,000 miles ago to see if it cleared up a locking torque converter (it did for the most part - can still be a bit lazy at times but it is much improved). The transmission has never slipped or miss...just runs a bit rough right now.

Anyways, this transmission has never been flushed, so as of now I'm wanting to get the most dirty fluid out as possible to see if I can get it to run a bit smoother. I'm willing to bet some old fluid is the culprit at this point.

So, how should I deal with this:

• Should I just drop the pan and change the filter/fluid in shorter intervals (every 5,000 miles) until I can get most of the old fluid out?
• Get it flushed (I know this can be harmful to older transmissions) since the transmission has never had any problems?
• Deal with it and save up for a new transmission?

I'm no transmission expert, so any suggestions would be appreciated.

[maxwedge]

Do not flush the trans more issues will pop up, it sounds like you may be nearing an o/h.

[jamesmetairie]

how much does it usually cost for overhaul at a good shop?

[ptcfast2]

Quick Update: I went ahead and installed a transmission cooler (the tranny is these cars runs hot to begin with) and changed the fluid & filter. It helped a bit, but not enough...

So, in randomness I decided to disconnect the electrical connector from the knock sensor in the block. I figured that since the engine is older it's possibly generating more noise than normal and causing the ECU to retard the timing a bit more.

With the knock sensor unplugged the engine ran smoother and shifting was smooth as butter. Better pickup, no more shaking on deceleration, no more hesitation. I took videos of both driving with the sensor plugged in and without it plugged in (pardon the shoddy camera).

No Knock Sensor
Note the ringing during the first acceleration 1:10 or so. It dissipates once I hit cruising speed at 60mph or so. It's normally around the most when the engine is cold, but the noise will come back randomly. Is this what engine ping sounds like? (Never heard engine ping before).
http://www.youtube.com/watch?v=JwdABMGLIWk

Knock Sensor
At around the 1:40 mark you will see the RPM suddenly jump. I didn't change my position on the pedal, but this is the main problem I'm talking about.
http://www.youtube.com/watch?v=kA-_T1zyCsQ

Maybe it was just me "imagining" it felt better, but the car just seemed to better with the sensor disconnected.

From the videos what would be your conclusion? I'm having a hard time diagnosing this one...