We have a 99 buick regal that has a little over 100K on it, it has the 3400 engine. When it'* cold when starting in the morning I have to shift into reverse to back out of the driveway. When shifting into reverse there'* a harsh bang. This doesn't seem to do it as bad when it'* warmed up and it'* only when shifting into reverse. Any ideas on what I can try to fix this?

I think that your engine mounts are bad. I wonder if the engine isn't idling higher when it starts cold and it really jumps when put into gear.

Could be a sticking or stuck reverse servo piston. This in on top of the trans near the shifting linkage. If the piston is stuck you will have a harsh engage. The piston acts as a shock absorber to give a smooth engage of the reverse band. When stuck the line pressure jumps right up to max and the shift is harsh.

Hey thanks for the quick reply. It is idling faster when it'* cold so this very well could be it. Is it an involved job replacing the mounts on this car? I have the repair manual at home and can check later on the details of the job, just wondered what I'm in for. Thanks again.

Mounts arn't real hard. But open the hood, with engine off and in park, push the car back and forth. Really get it rocking. Does the engine move a lot in the bay? If not, the mounts are not bad. If you see it moving a lot, try to look around while it'* rocking. The front drivers side trans mount is a good one to go back, unless you have dog bone mounts, I don't recall.

Thanks for the reply. Is this servo piston external to the transmission? I replaced a few of these transmission on a 3100 engine but I can't remember many details about them. Is there a way to check this? Thanks.

I'll check this out tonight and get back to you guys with what I find, thanks again for the help.

Is this a 4t65e trans? If so, yes, it'* right on top, drivers side behind the throttle body. You should see a round disk, that'* the top. I believe it'* held in place by a retaining ring.

Honestly, I thought all of the Regals got 3800s and Centurys got 3100s.

You will likely see plenty of rocking in this car. But uh.. 99 Regal wasn't available with a 3400 and as far as I know the Century was only available with a 3100. Either way.. all the mounts are the same. The two lower ones are easy to see through the wheel wells. Likely the passengerside lower is soaked in oil and has disintegrated.

On the upper mounts, you may want to flip the rubber in the front pieces. That helps take a lot of play out of the mounts.