Monday, December 12, 2011

How to Replace Power Brake Booster on 1996 GMC Jimmy?

Most all modern vehicles use power assisted brakes. A vacuum line from the intake manifold to the brake booster provides a source of vacuum.Most power brake boosters are vacuum operated devices requiring approximately a minimum of 17 inches of vacuum to operate. The brake booster is the round, black canister located at the back of the engine compartment on the driver's side of the Vehicle.It uses vacuum from the engine to increase the force that your foot applies to themaster cylinder.
The power brake booster is a tandem vacuum suspended unit. Some models may be equipped with a single or dual function vacuum switch which activates a brake warning light should low booster vacuum be present. Under normal operation, vacuum is present on both sides of the diaphragms. When the brakes are applied, atmospheric air is admitted to one side of the diaphragms to provide power assistance.

Follow the procedure mentioned below for REMOVAL & INSTALLATION of power brake booster on your GMC Jimmy.
1994-97 Models

See Figures 1 and 2
Apply the parking brake and block the drive wheels.
Remove the master cylinder-to-power brake booster nuts, then reposition the master cylinder and combination valve out of the way; if necessary, support the master cylinder on a wire to prevent damaging the brake lines.
When removing the master cylinder from the power brake booster, it is not necessary to disconnect the hydraulic lines, therefore the brake system should not have to be bled.
Disconnect the vacuum hose from the power brake booster.
See the diagram below:----


Fig. Fig 1: Common power brake booster attachment

From under the dash, remove the retainer and washer from the brake pedal on 1994 utility models. On all other models, remove the retainer and brake switch from the brake pedal.
Disconnect the pushrod from the brake pedal.
From under the dash, remove the power brake booster-to-cowl retaining nuts.
Back under the hood, remove the power brake booster and the gasket from the cowl.
To install:

Position the booster to the cowl using a new gasket.
Install the bo oster retaining nuts and tighten to 16 ft. lbs. (22 Nm) 1994 utility models, 24 ft. lbs. (32 Nm) on 1994 pick-up models and 27 ft. lbs. (36 Nm) on all 1995-97 models.
Connect the pedal pushrod and install the washer or switch and the retainer.Connect the vacuum hose.

Fig. 2: Checking the piston booster rod using the gauge tool
For all vehicles cover ed in this guide, gauge the booster rod:
Apply 25 in. Hg (85 kPa) of vacuum using a hand held vacuum pump or apply maximum engine vacuum.
Chec k the maximum and minimum rod lengths using J-37839 or an equivalent pushrod height gauge.
If the piston is not within limits, install a service adjustable piston rod and adjust it to the correct length.
Reposition the master cylinder and combination valve bracket to the booster studs, then secure using the retaining nuts. For details, please refer to the master cylinder procedure located earlier in this section.
Start and run the engine, then check for proper booster operation.

This details will help you.
If you need dis-assembly or replacement instructions for any other auto/car part, or you want to ask question related to your car/truck jeep problem then please leave the comment with your details, so I can provide you the required instructions and solutions.

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