Century transaxle

I have a 2000 Buick Century. At about 50000 miles the transaxle (4T65E) started shifting very rough, slammed into all upshifts. Dealer replaced the pressure control solenoid in transaxle ($500+). Solved the problem for about a year. Now at about 90000 miles problem is reoccurring. Currently as before, very intermittant. I drive 95% highway miles at 65mph. Anyone have any ideas what would cause this?

Highway miles are the best miles to put on your car, I can't imagine anything being wrong! Wait until Flatrater or pcv comes around.

When it acts up there no doubt that something is wrong. Almost gives me a whiplash on each up shift and theres a definent whine from the engine compartment. After it sits, usually overnight, it's normal again for a few days.

When it acts up there no doubt that something is wrong. Almost gives me a whiplash on each up shift and theres a definent whine from the engine compartment. After it sits, usually overnight, it's normal again for a few days.

My 2000 Buick Century is doing exactly the same thing!
It has approximately 50000 miles on it and hasn't been driven hard.
We checked the fluid when this occurred and it was approximately
3 inches above the full mark. I let the car cool down and then started
it up again and checked it after I drove it around the block and it was
right on the full mark. Our car started shifting hard when we were in
heavy traffic, so I concluded that the transmission overheated.
I'm taking my car to the transmission shop Monday, so I guess I'll
find out then what it is. I'll let you know what I find out.
Joe

Here is a article I found on the problem. http://www.gearsmagazine.com/2002-09/2002_09_48.pdf It maybe of some help to you to read before taking your car into the tranny shop.
When they tell you it needs a new pressure control solenoid keep in mind that I had one put in $500+ and it worked for about a year, then back to the hard shifting. It is very intermittant and it seems if I control my accelleration I can control the problem (maybe). Keep me posted of what you/they find. thanks for the reply.

Also, I had three tranny shops look at mine prior to the dealer installing the pressure control solenoid. Two of the three tranny shops said I needed a $2100 tranny rebuild, the third said a new torque converter was needed. When I called the dealer and described the symptoms, they acted like they new exactly what I was talking about, gave me the impression that they had several similar problems and maybe a service bulletin on the issue.

Also, I had three tranny shops look at mine prior to the dealer installing the pressure control solenoid. Two of the three tranny shops said I needed a $2100 tranny rebuild, the third said a new torque converter was needed. When I called the dealer and described the symptoms, they acted like they new exactly what I was talking about, gave me the impression that they had several similar problems and maybe a service bulletin on the issue.

There is at least one service bulletin on this trans. The one I heard
of has to do with a defective drum in the trans that falls apart and
destroys the transmission!
I think auto makers have been making automatic transmissions since
1932; you'd think they would have them perfected by now!!
Joe

Also, I had three tranny shops look at mine prior to the dealer installing the pressure control solenoid. Two of the three tranny shops said I needed a $2100 tranny rebuild, the third said a new torque converter was needed. When I called the dealer and described the symptoms, they acted like they new exactly what I was talking about, gave me the impression that they had several similar problems and maybe a service bulletin on the issue.

Talked to the tranny man today. He told me he was doing some
updates to my transmission. "Updates" I guess are what should be in
your trans when it was new but isn't. He kinda explained that when the
trans is warmed up it sends a signal to the computer and it compensates
by sending more fluid through an orfice or something like that. Anyway,
he said he has to remove the transaxle to repair it. The repair is sup-
posed to cost around $700-$800; I told him to go ahead and do it.
Joe

Talked to the tranny man today. He told me he was doing some
updates to my transmission. "Updates" I guess are what should be in
your trans when it was new but isn't. He kinda explained that when the
trans is warmed up it sends a signal to the computer and it compensates
by sending more fluid through an orfice or something like that. Anyway,
he said he has to remove the transaxle to repair it. The repair is sup-
posed to cost around $700-$800; I told him to go ahead and do it.
Joe

Latest update on the Buick!
Got the car back today--Parts replaced were a boost valve kit,
EPC solenoid, filter, fluid and gaskets. Total cost, parts and labor,
$675. Turned out better than I thought. Trans man says it should
be good for many miles. Oops... the solenoid thing sounds like what
the other fellow had done. Tranny man also said a trans fluid cooler
wouldn't be a bad thing if I could find a place to put it!!
Joe

you shouldnt need a cooler, but the factory one bolts on in front of the radiator