Car Problem Reports

Chevrolet Astro Power Brake Units May Leak Fluid From Hydro-Boost Unit

Chevrolet Astro Problem
29 Reports
Me Too

Model Years Affected: 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005

Average Mileage: 178,567 mi (138,000 mi - 229,571 mi)


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.

  •  Rookie

    Leaks power steering fluid from the hydro-boost unit located behind the brake master cylinder

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  • Visitor, , 176,000 mi

    Fluid leaks from my 97 astro Hydro boost, so I rebuilt it and now it's leaking again. Someone out there has to have a fix or recall for this problem. You buy a rebuild kit and it comes with 4 page instructions, and does not go far enough to help.

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  • Visitor, , 138,000 mi

    hydro-boost pump suddenly began to leak large quantities of power steering fluid.

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  • Leaking PS fluid out of Hydro Booster. Replaced Hydro Booster.

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  •  Rookie


    CAR, YEAR, MODEL: Chevy Astro 8-Passenger Van Rear Wheel Drive, ABS Disc Brakes.

    DIAGNOSIS: HYDRO BOOST UNIT BROKEN/CRACKED, resulting in loss of Power Steering and Braking functions.

    DATE OF INCIDENT: Dec 06, 2012: CAR,YEAR,MODEL: 1999 Chevy Astro 9-Passenger V-6 Van. Brake Failure was complete surprise, because I had just retrieved my van from specialist brake shop where I'd taken it to have my brakes inspected and repaired because brakes felt "spongy". Repair shop found my brakes worn to a dangerous 5% surface and needed replacement. Cost $643.95 for CE Front Brake Pad, Rear Brake Shoes, Rear Brake Hardwear Kit, Front Grease Seals, Brake labor,Turn Rotor/Drums, Front Outer Bearings, Front Inner Bearings.

    I thought it was unusual to need this Dec. 06 brake job because I'd had my brakes inspected and repaired about a year previous, for the same symptoms..they felt "spongy" and had worn down to a dangerous level. I thought this rapid wearing down of my brakes was due to driving conditions on a long downhill slope to town (I average about 150 miles per week, stop and go in town (30 mph)and highway driving (60 mph).

    DRIVING CONDITIONS ON DATE OF BRAKE FAILURE: Downtown, suburban 5:00 PM rush hour traffic, driving speed 25-30 mph, on well maintained dry and smooth road surface in early evening daylight and clear weather, in San Anselmo, CA Red Hill Shopping Center area.

    SEQUENCE OF EVENTS DURING FAILURE: While pressing brake pedal to stop at red light, I heard cracking-clunking noise. Suddenly felt no resistance from brake pedal and simultaneously felt steering go "hard". Also smelled burning odor (rubbery-chemical) coming from dashboard. Fortunately, there was no cross traffic, or pedestrian(s) in cross walk and no cars ahead of me as I kept going through red light. I was able to eventually halt the car by steering towards the concrete curb of the sidewalk in order to slow my progress by creating friction between my tires and the curb.

    Brake fluid had "poured" onto road. Several men volunteered to help push my car off the road & out of traffic but I was not able to shift into Neutral gear; I did not want to force the gear shift arm because I was afraid I would break the gear shift arm. Ca AAA tow truck took my van to the same repair shop that had that day just fixed my brakes.

    DIAGNOSIS FOR CAUSE OF FAILURE: Hydro Boost Unit had cracked/broken. Shop did not have explanation for Hydro Boost Unit failure other than possible metal fatigue in Hydro Booster Unit. Replacement of Hydro Boost Unit cost $1,423.47, plus costs of UPS 2nd Day Air for parts.

    NEW SYMPTOMS, POSSIBLE NEW PROBLEMS: Dec 26, 2012, Check Engine Light (CEL)turns on only while making right turns (while driving at 30mph to 60mph speeds, and also when accelerating from full stop to make a turn right into moving traffic). This only occurs when steering right. CEL does not turn on while steering left.

    These new symptoms are worrisome. Called same brake repair shop. Will take car to them first thing tomorrow AM for trouble shooting session.

    QUESTION FOR DISCUSSION GROUP: Has anyone else experienced this? Thanks for any tips.

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  •  Enthusiast

    Having new line installed to take care of this.

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