Automatic transmission engaging with a thud on cold days

I don’t know enough about automatics to assess what’s wrong with my son’s transmission, so any advice would be appreciated.

The car is an 89 Grand Am with 113,000 miles. What is happening is that when you put the car into a forward gear nothing happens until you increase
the rpm’s and then it engages with a thud. The odd thing is that it only happens on cold days and then only on initial start up, after it engages the car seems to drive and shift find. The colder it is the higher the rpm’s has to be raised before it will engage. The problem does not occur in reverse no matter what the temperature.

Any ideas?

Thanks in advance for any replies.

Gene from Georgia

Sounds like a bad trany, possbly the torque converter is broken.
Have you tried to get it scanned for trouble codes ?

a clogged transmission filter could cause your issue

Sounds like a sticking solenoid in the trans to me. I been around trans shops for several years, and that's a fairly common problem. There a fairly simple change (for a trans shop) that doesn't require removal of the trans, but it needs to be fixed before all that rough engagement breaks something else.
I hope that helps.

I changed the transmission filter, but there doesn't appear to any difference. It's hard to tell though, because the problem is directly effected by the outside temperature and that's been all over the place of late.

Again, the car drives and shifts find after the initial engagement and on cold days that comes with a thud, on warm days there is little or no thud.

Since the car is going 20 years old my son will just live with the problem until the transmission dies completly and then get rid of it.

Thanks for all the replies.

Gene from Georgia

Hi Gene,

I had a '71 Mustang that did the exact thing. Cause it went into reverse I figured the pump was still working fine. Bought a kit and torque converter and rebuilt it myself. Worked great after. Don't think I would try it on a newer car. I agree that your son should drive it til it quits and then get something else. Probably the most cost effective way to go. Heck, it might go another 50k if he's careful with it. Good luck.

Well the TCC is prone to failure on this model grand am. It can be changed by a DIY'r. :2cents:

http://autorepair.about.com/cs/doityourself/l/aa011703b.htm