Bit Rough from Park into Reverse after startup?

[r171mb]

In the new to me 08 Aero with Automatic 6 Speed:

After startup especially cold start up, when I go into reverse it's rougher than I experience in other automatics. It's not a clunk necessary, you just really "feel," it.

Now, if the transmission is warm from driving, it doesn't really seem to do this when going from park to reverse.

Is this probably normally operation? Any guesses? How does yours feel? Thanks!

[Burnsside42]

This is a normal feel for those V6 cars. how is your brake function/feel @ cold starts? If you have a lack of brake @ cold start then it needs the check valve/pump located in the right front fender.

[r171mb]

Thanks Burnsside42, good to hear that is normal.

Sadly, yes I have that lack of brake boost on cold start. I was going to replace this vacuum line with check valve: 12847289.

However, I understood this was all behind the engine near firewall. I have read this part has fixed the issue for others.

Is this pump and check valve you mentioned of in the fender on a V6 too?

I wonder which I really need or both?

Thanks.