cold tranny won't shift from Park until warm-up happens

My friend has a 1994 Buick Park Avenue and has to "warm-up" the engine for 5-10 minutes before the transmission can be shifted from 'Park' into 'Drive' or 'Reverse'. Lever moves, but transmission does not engage. This happens even in summer when the car has been sitting for several hours, but the "warm-up" time is less than in winter months when it can take up to ten minutes. Several repair shops have checked it out and could not locate the problem. Anyone ever hear of a problem like this? Appreciate any info you can pass along.

If it was mine, I'd check the fluid first, then I'd check to see if I had any codes, if none, I'd check for vacuum leaks and the vacuum modulator, if all good, then I'd do a FULL fluid/filter exchange to rule that out. Has any of this been done and/or checked lately?

P.S. This Automotive Forums site has answered every problem I've had with my Buick that those service repair shops couldn't.

You have internal seal problems, this link may help;
http://www.buickforums.com/forums/showthread.php?t=2000

If it was mine, I'd check the fluid first, then I'd check to see if I had any codes, if none, I'd check for vacuum leaks and the vacuum modulator, if all good, then I'd do a FULL fluid/filter exchange to rule that out. Has any of this been done and/or checked lately?

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This is exaclty correct. I was having similar problems, however the transaxle was baked by the previous owner when I bought my car 6 years ago. I rebuilt it then, but it started having minor problems to this effect 2 winters ago, only when extremely cold, then all of the sudden this summer it wouldn't move at all, even after 30 min. of perfectly fine driving. Since I'm still under the "150K lifespan" of the trans and didn't have the time or money to repair or replace, I gave it a shot and now it's shifting even better in the winter than summer and right away.

You have nothing to loose by changing the fluid and filter. I don't think you have a vacuum mudulator tho, yours s/b electronicly controlled for pressure.

If it was mine, I'd check the fluid first, then I'd check to see if I had any codes, if none, I'd check for vacuum leaks and the vacuum modulator, if all good, then I'd do a FULL fluid/filter exchange to rule that out. Has any of this been done and/or checked lately?

P.S. This Automotive Forums site has answered every problem I've had with my Buick that those service repair shops couldn't.

Each shop she had check it out took some corrective steps, based on the symptoms; I will have to check the paper work on what exactly was completed. Supposedly the filter and fluid were changed at least once recently and hoses replaced. The car has only 75K miles and is maintained regularly.

Check the torque converter.

Mike

They call it "Morning Sickness". Inside the transmission there are lip seals , regular O-ring type , and flat. The Lip seals usually dry up get old and brittle-thus shrinking and letting oil pass right by them so the clutch piston cannot engage the pack.. when its cold they shrink that much more. I've taken seals off that were baked on practically- had to chip them off the drum (no seal whatsoever) , and the opposite someone who put a can of tranny fix all which is just a petroleum distilate that softend the ribber up a bit (Quick fix that just doesn't last) . These seals are flabby to say the least. You take they clutch drum out and they fall off. In any regular car As your car warms up, the seals also get warm -expand to the point where they can hold pressure and your on your way. Just something I learned 20 years ago.. Merry Christmas all.