Transmission problem?

[daworz]

Hey,
I have a 95 Pontiac Transport 3800, And have been having problems with the transmission when i run it in Overdrive it seem too shift back and forth, it hard to put words with it, Its just seems too want to shift contuiously, i checked the fluid as it says in the book and the fluid is in the normal operating range! Any ideas would be great....

[LMP]

..mmm..what happened with your wandering idle problem?
'bout transmisison..is this a new problem that has developped on a sudden or did the condition worsen with time? I understand that when the shifter is in position OD, the car will shift in and out of...4th gear?, so between 3 and 4.... or is it the TCC that engages or disengages...
If you keep it on D , what happens? (TCC will also engage on 3rd gear).

[daworz]

Sorry for the delay!
Know it started when i was driving back from Ft.myers Beach when i was in alot of traffice and in over drive it seemed loked it shifted back and forth so i would put it in just D and it seemed ok then when i would get up too speed over 50mph i would shift it too OD. The trip was around 1000 miles down and back, I never had any warning lights come on, What is TCC, I would think if my tranny was going bad i would have lost it by now? Wandering idle problem it idles fine? It seems to be about like it was not any worse or better?

[LMP]

TCC (torque converter clutch) is a small clutch that locks up the torque converter just as a standard clutch once the car is up to speed in 3rd of 4th gear. This avoids fluid slip and saves gas.
SO when TCC operates and you are on D...it will look as having 4 gears cause it will through 1,2,3 and then engage TCC which will lower the engine rpm again. If you are in OD, it may go through 1,2,3,3+TCC and 4+TCC or depending on throttle position, proceed through 1,2,3,4,then 4+TCC
TCC is a small clutch and cannot support high torque from engine so as soon as you move throttle down a little bit fast, TCC will open and you are back on torque converter operation and engine will gain 400 or 500 rpm almost like it has shifted gears, but it has not. As soon as you are at steady speed and throttle, TCC will engage again.
TCC operation can be impaired by faulty Throttle Position Sensor but this will throw the CheckEngineLIght on. YOU did not mention if your CEL is on..in which case you would have to read the codes....

[guido0136]

I was also having the same problem, it turned out the the tranny cooling lines in the rad had blown a leak and fluid was leaking into the rad, and lowering the fluid in the tranny, and I was have the same problem (slipping from 4th to 3rd) I was hoping I would not have to change the rad, so I stuck stop leak in both the rad and tranny, and currently (knock on wood) all seems fine.

Hope this helps.

[maxwedge]

Originally Posted by guido0136

I was also having the same problem, it turned out the the tranny cooling lines in the rad had blown a leak and fluid was leaking into the rad, and lowering the fluid in the tranny, and I was have the same problem (slipping from 4th to 3rd) I was hoping I would not have to change the rad, so I stuck stop leak in both the rad and tranny, and currently (knock on wood) all seems fine.

Hope this helps.

What did you do about the coolant/ trans fluid intermix? The cooler tank in the radiator sealed up with trans sealer/cooling system sealer? This system is under about 25psi, must have been miracle stuff.

[guido0136]

It's only been 2 weeks since I added the stop leak. I'm still unsure if it has worked. So far the tranny fluid is steady. The rad fluid is now a yellowly green mix, it still seams to cool okay, but I have already spent some wasted money on flush and fill. I would like to make sure any and all seals are fixed before I pay for another flush/fill.

Guido

Guido,
rad stop will do a nice job on your heater core as well...plug it up real good.
You are risking blowing your tranny for sure...its only a matter of time...fork out the 250 & save yourself 2,500!!