97 Sierra tranny problems?

[1997Sierra]

Hi guys. I just joined the forum and it seems like a great place. I have a few questions one my 97 Sierra. It has a 350 and a automatic tranny. THe truck has 90,000 miles and has been good to me until a few weeks ago. The tranny in the truck started to shift hard all the sudden. I drove it on the freeway for about twenty miles and then stopped and tried to take off. The tranny jammed into gear between first and second and second and third. I brought it in and the guys at GM said that it was in need of a flush. They flushed it and it was ok for a week then it started again. Not as bad but it is still apparent. I was told these trucks had problems with the valve bodies? I beleive this is the 4L80E tranny. Any suggestions. I am still driving it around and it runs good but the shifts are not what they should be. My Dad has the same tranny in his 2003 Silverado with the 5.3 but they were known to make noise. Any help would be great.

[GMMerlin]

Originally Posted by 1997Sierra

Hi guys. I just joined the forum and it seems like a great place. I have a few questions one my 97 Sierra. It has a 350 and a automatic tranny. THe truck has 90,000 miles and has been good to me until a few weeks ago. The tranny in the truck started to shift hard all the sudden. I drove it on the freeway for about twenty miles and then stopped and tried to take off. The tranny jammed into gear between first and second and second and third. I brought it in and the guys at GM said that it was in need of a flush. They flushed it and it was ok for a week then it started again. Not as bad but it is still apparent. I was told these trucks had problems with the valve bodies? I beleive this is the 4L80E tranny. Any suggestions. I am still driving it around and it runs good but the shifts are not what they should be. My Dad has the same tranny in his 2003 Silverado with the 5.3 but they were known to make noise. Any help would be great.

You most likely have the 4l60-e trans in your truck and for the most part they do not make any noise.
The harsh shift may be from a sticking valve. There are some valve body issues with those trucks when they get some miles on them.
I am concerned when trans flushes are done on vehicles over 50k and those with transmission issues.
You may be heading back with a slipping trans in the future.
BTW..have you ever serviced the trans before this problem occurred?

[1997Sierra]

Originally Posted by GMMerlin

You most likely have the 4l60-e trans in your truck and for the most part they do not make any noise.
The harsh shift may be from a sticking valve. There are some valve body issues with those trucks when they get some miles on them.
I am concerned when trans flushes are done on vehicles over 50k and those with transmission issues.
You may be heading back with a slipping trans in the future.
BTW..have you ever serviced the trans before this problem occurred?

Thanks for the help! I have never serviced the transmission before in this truck. The flush seemed to help. I think the sticky valve body is the problem. I have talked to others and they have said that the valve body is most likely the problem. Any idea what it costs for a valve body? I do not know if you can buy individual parts or not. Any ideas or suggestions. Thanks again.

[MyTOY]

My 97 5.0 had same prob. Slamming into 2nd after
going into overdrive. I found out it's common &
there are valve body bore kits to fix but
too late for mine - needed rebuild. When I had this
prob., turning it off for a second & restarting would
stop the computer from telling the trans. to go nuts.
Also, it wouldn't go back into overdrive in that condition.
Probably why I needed a new T.C. also.

[aaamillertime]

Originally Posted by 1997Sierra

Hi guys. I just joined the forum and it seems like a great place. I have a few questions one my 97 Sierra. It has a 350 and a automatic tranny. THe truck has 90,000 miles and has been good to me until a few weeks ago. The tranny in the truck started to shift hard all the sudden. I drove it on the freeway for about twenty miles and then stopped and tried to take off. The tranny jammed into gear between first and second and second and third. I brought it in and the guys at GM said that it was in need of a flush. They flushed it and it was ok for a week then it started again. Not as bad but it is still apparent. I was told these trucks had problems with the valve bodies? I beleive this is the 4L80E tranny. Any suggestions. I am still driving it around and it runs good but the shifts are not what they should be. My Dad has the same tranny in his 2003 Silverado with the 5.3 but they were known to make noise. Any help would be great.

So familliar. Mine 97 silverado does the same thing. It started when I had about 80,000. It's been over two years now. I have 131,000 on it. Guy at the tranny shop told me that more than likely it's a valve sticking, I could rebuild or learn to live with it. For $1200 bucks I decided to learn to live with it.

[70camaro]

it may be too late for some but for others try using the max life trans fluid when you flush. mine started doing it too, had it flushed good asap with max life and now it's working fine.

[blabhern]

I just use a good trans conditioner when I replace the fluid and filter every year in mine.