THe proportioning valve (height sensing) could be leaking or the brake lines going to it. You need to check the brake lines to make sure there are no holes from rust, make sure the fittings are tight, and if there is still a leak, the valve may need replaced. PLEASE NOTE: Chances are it will only get worse. Therefore, I recommend repairs before using the vehicle.
Let me know what you find or if you have other questions.
Joe
Friday, December 17th, 2010 AT 12:34 AM