I took the truck to the dealer for the recall that pertains to accumulator overpressure and failure. The info from GM says that they think there should only be 90 trucks worldwide that will have the faulty pressure relief valve that can cause the accum to blow off. They have a tool that they use to test the relief valve. They remove the feed line from the booster and install a 6" clear hose in its place. A tool is bolted to the unit that allows them to apply pressure to the end of the accum. As the accum is pressurized, a small amount of fluid should flow in the hose. They did it twice, no fluid moved. I find it hard to believe that I have one of the 90 bad ones, so either the test doesn't work or perhaps GM has greatly underestimated the amount of bad ones. Anyway, they have ordered a booster, which I assume will also have the O ring TSB covered. I would like to see the test done on another truck just to see it work right. I have Hydra-Boost on my 'burb, maybe I'll borrow the tool from them and see how it responds. Any of you techs done this procedure yet? If so, what were the results?

Had my HB replaced to fix a steering noise.

What O-Ring TSB are you talking about? Have a link to it?

Make : CHEVROLET Model : SILVERADO Year : 2004
Manufacturer : GENERAL MOTORS CORP.
NHTSA CAMPAIGN ID Number : 04V045000 Recall Date : JAN 28, 2004
Component: SERVICE BRAKES, HYDRAULIC
Potential Number Of Units Affected : 68875
Summary:

CERTAIN SPORT UTILITY VEHICLES, PICKUP TRUCKS, AND PASSENGER VANS FAIL TO COMPLY WITH THE REQUIREMENTS OF FEDERAL MOTOR VEHICLE SAFETY STANDARD NO. 135, ?PASSENGER CAR BRAKE SYSTEMS.? SOME OF THESE VEHICLES WERE PRODUCED WITH AN OUT-OF-SPECIFICATION BRAKE HYDRO-BOOST HOUSING RELIEF VALVE BORE.

Consequence:

CONSEQUENTLY, THE VALVE O-RING SEAL MAY FRACTURE. STEERING EFFORTS MAY BE SLIGHTLY INCREASED WHILE BRAKING OR PARKING. UNDER CERTAIN DRIVING CONDITIONS, A FRACTURED SEAL MAY REQUIRE A SLIGHT INCREASE IN THE APPLIED BRAKE PEDAL EFFORT TO ACHIEVE THE SAME VEHICLE DECELERATION RATE AS PRIOR TO THE SEAT FRACTURE.

Remedy:

DEALERS ARE TO REPLACE THE HYDRO-BOOST RELIEF VALVE. THE RECALL BEGAN ON APRIL 26, 2004. OWNERS SHOULD CONTACT CADILLAC AT 1-866-982-2339; CHEVROLET AT 1-800-630-2438; GMC AT 1-866-996-9463; OR HUMMER AT 1-866-486-6376.

Notes:

GM RECALL NO. 04004. CUSTOMERS CAN ALSO CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION’S AUTO SAFETY HOTLINE AT 1-888-DASH-2-DOT (1-888-327-4236).




Make : CHEVROLET Model : SILVERADO Year : 2004
Manufacturer : GENERAL MOTORS CORP.
NHTSA CAMPAIGN ID Number : 05V043000 Recall Date : FEB 04, 2005
Component: SERVICE BRAKES, HYDRAULIC
Potential Number Of Units Affected : 155465
Summary:

CERTAIN TRUCKS, SPORT UTILITY VEHICLES, AND VANS EQUIPPED WITH BOSCH HYDRO-BOOST BRAKE ASSEMBLIES, THE HYDRAULIC BRAKE BOOSTER PRESSURE ACCUMULATOR MAY CRACK AND SEPARATE FROM THE HYDRO-BOOST ASSEMBLY DURING NORMAL OPERATING CONDITIONS.

Consequence:

IF A SEPARATION OCCURRED AND THE HOOD OF THE VEHICLE WERE OPEN, FRAGMENTS FROM THE ACCUMULATOR COULD CAUSE INJURY TO PEOPLE IN THE IMMEDIATE AREA. THE PRESENCE OF THIS CRACK OR FRACTURED SURFACE COULD ALLOW THE HYDRAULIC FLUID TO LEAK FROM THE ACCUMULATOR CIRCUIT OF THE BOOSTER ASSEMBLY. THE LOSS OF FLUID WOULD CAUSE INCREASED STEERING AND BRAKING EFFORT AND A CRASH MAY OCCUR WITHOUT PRIOR WARNING.

Remedy:

DEALERS WILL TEST THE HYDRO-BOOST ASSEMBLY FOR FUNCTIONAL OPERATION OF THE TWO-FUNCTION VALVE. IF THE HYDRO-BOOST ASSEMBLY FAILS THE TEST, DEALERS ARE TO REPLACE THE ASSEMBLY. THE RECALL IS EXPECTED TO BEGIN DURING MARCH 2005. OWNERS SHOULD CONTACT CHEVROLET AT 1-800-630-2438, GMC TRUCKS AT 1-866-996-9463 AND HUMMER AT 1-800-732-5493.

Notes:

GM RECALL NO. 05006. CUSTOMERS CAN ALSO CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION’S AUTO SAFETY HOTLINE AT 1-888-327-4236.

They sent out a message about the importance of lubing the tool before each use. If it's not, the results will be wrong due to the incorrect torque being applied. Too many boosters are being replaced already.

GMCSID, do you have a reference # that I could give them about the tool lube message? I would like them to do the test again after lubing before they change the unit.

Message# VSR20050007 04/08/2005

Thanks, I'll let you know the outcome.

Per GMCSID's advice, I asked the dealer to lube the bolt on the testing tool before rechecking it. They did this, and this time my unit passed the test. So, I didn't have to get it changed for nothing. If you take it in for the recall, make sure they lube the tool before they use it.

I always lube my tool before using it....):h Seriously though, if the tool isn't lubed it will fail them everytime.