I've got moderate vibration (almost a knocking sound) in my '87 944S, most noticeable at idle and low RPM. Here's the weird part--it tends to appear/get worse when I'm moving under power and I turn to the right. It's not a wheel bearing; it's definitely related to engine RPM, and it sounds like it's coming from the front half of the car somewhere. The right motor mount has been changed, and both looked okay last time I was under the car, but I'll measure them both this weekend to be sure. There's also quite a bit of vibration in the shifter. I'm going to check the balance shaft alignment, too, while I'm under there.

Could this be happening because I've got two different types of engine mounts (left side original)?

Thanks.

 

check if your power steering pump pulley , i've heard it comes loose often.... makes great sense for the one thats effected by turning. have somone turn the wheel while its running while you look? (keep your fingers out of there while its running though!