As stated I have a 85 seville with a 4.1 (34000 mi). The problem is that after a long drive at interstate speed the motor sound like it has a knock coming from the front drivers side of the motor. I suspected the vacume pump so I removed it after driving the car long enough to get it to make the knocking sound. that stoped it. So I put the new vac. pump on then a couple days later after driving at highway speed it started knocking agian.If I let it sit for a while it wont do it and it won't do it on short trips or if my avg. speed is below 55mph or so. I am suspecting the p/s pump maybe? any one heard of or had this problem? Any help is greatly appreciated.