Power brake systems using "hydro-boost" may leak power steering fluid from the hydro-boost unit located behind the brake master cylinder. Replacement of the hydro-boost unit is the common repair to correct this concern.
Car Problem Reports
GMC 3500 Pickup Power Brake Units May Leak Fluid From Hydro-Boost Unit
GMC 3500 Pickup Problem
Average Mileage: 160,750 mi (125,000 mi - 198,000 mi)
Visitor, 1998 GMC 3500 Pickup, 170,000 mi
leak at brake booster
Visitor, 1997 GMC 3500 Pickup, 150,000 mi
not fixed yet but checked out defently leaking there
Visitor, 1990 GMC 3500 Pickup, 198,000 mi
cant find booster with pushrod instaled from reman. company anywhere
Visitor, 1997 GMC 3500 Pickup, 125,000 mi
Leaking from P/S fluid from hydroboost unit, replaced unit.