from your description there are 2 possible places to look closely


1. the line connection from the front of the car which become a short rubber flex line as it becomes airborne to connect it to the junction fastened to the top of the axle

2. or the junction on the top of the axle.


if it is #2. you can loosen, clean it up and re tighten or merely retighten to see it that does it

it if it is #1 you are likely looking at replacing that flex line. this can be seriously difficult because you often a have a lot of rust where the rubber line fastens to the all metal line from the front of the car