4th gear slipping

[RickA]

Hi all,
New to the forum here and hoping for some advice. My 2000 GT 3.8 is slipping in 4th/OD. I have replaced the filter and fluid but no change. It shifts fine and only slips in 4th. $$ is tighter nowdays than ever. I am a pretty good home mechanic and I have done all of the maintenance on this car since it was new. I also have the factory GM service manuals for the car. Anyways, my main question is there a chance of fixing this problem without removing the transmision. If it comes to having to remove the tranny, I will likely have a pro do it. Which leads me to ask if I can't do this job without removing the tranny, does anybody have any referals to a good honest and fair priced tranny guy around Atlanta GA.
Thanks for your help.

[QUICKSILVER462]

My Tranny had a slight overrun going shifting from 3rd to 4th and I just raised the shift pressure with my JET DST a few psi and it solved the problem, it does have 150,000 on it!
Maybe you get get someone to try to tune it out untill you get a chance to get a rebuild.
Mines a 2000 too.

Dean

[TheOtherNick]

Yeah you would try having some one bump up the line pressure in the tranny a bit to see if it will help.

[RickA]

Thanks for the replys. You think this has a chance of helping even though it shifts into OD with no problems at all, it is just that 4th/OD slips real bad. The tach goes to about 3400 at 65mph and there is a bad whining noise. If I shift back to 3rd, all is well and it will shift back into 4th with no problems, well except for the slipping. I don't know a lot about automatic trannys but I figured the pressure would affect shifting, not slipping.

[QUICKSILVER462]

Chanses are, if you drove with it slipping like that for any amount of time, the clutches are turning to toast. When they get like that, it;s all down hill from there.
I would get some sort of scan tool so you can see what the pressures are in it if I were in the same situation.