ISUZU Amigo/Pick-ups/Rodeo/Trooper 1981-1996

Power Brake Booster

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REMOVAL & INSTALLATION



Except Hombre

See Figures 1 and 2



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Fig. Fig. 1: Power brake booster assembly-except Hombre



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Fig. Fig. 2: Measure the pushrod length

  1. Disconnect the negative battery cable.
  2.  
  3. Firmly set the parking brake and block the wheels.
  4.  
  5. Disconnect the vacuum hose to the booster.
  6.  
  7. Using a turkey baster or other suitable device, remove as much brake fluid from the reservoir as possible.
  8.  

Brake fluid is highly corrosive to paint. Take care not to spill brake fluid on any painted surface of the vehicle.

  1. Tag the brake lines installed to the master cylinder. Use a line wrench to loosen and disconnect the hydraulic lines from the master cylinder. Immediately plug the lines to prevent system contamination or excessive fluid loss.
  2.  
  3. From inside the vehicle, remove the snapring from the clevis pin and separate the clevis pin from the brake pedal.
  4.  
  5. From inside the vehicle, remove the vacuum booster mounting nuts at the firewall.
  6.  
  7. With all the nuts removed, lift out the master cylinder and brake booster as an assembly.
  8.  
  9. Separate the master cylinder from the brake booster.
  10.  

To install:
  1. If the master cylinder was removed, install the unit to the brake booster.
  2.  
  3. Before installing the power brake booster, check the distance from the flange face of the booster to the end of the pushrod.
  4.  
  5. Install the brake booster/master cylinder to the firewall and secure in place with the retainer nuts. Tighten the vacuum booster nuts to 14-16 ft. lbs. (18-21 Nm).
  6.  
  7. Install the brake lines and tighten the fittings to 105 inch lbs. (12 Nm).
  8.  
  9. Connect the negative battery cable.
  10.  
  11. Bleed the brake system.
  12.  

Hombre
  1. Disconnect the negative battery cable.
  2.  
  3. Firmly set the parking brake and block the wheels.
  4.  
  5. Disconnect the vacuum hose to the booster.
  6.  
  7. Using a turkey baster or other suitable device, remove as much brake fluid from the reservoir as possible.
  8.  

Brake fluid is highly corrosive to paint. Take care not to spill brake fluid on any painted surface of the vehicle.

  1. Remove the master cylinder-to-brake booster retainer nuts. Position 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.
  2.  

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.

  1. From under the dash, disconnect the pushrod from the brake pedal. Remove the brake switch.
  2.  
  3. From under the dash, remove the power brake booster-to-cowl retaining nuts.
  4.  
  5. Remove the power brake booster and the gasket from the cowl.
  6.  

To install:
  1. Position the booster and new gasket in place in the engine compartment.
  2.  
  3. Install the booster retaining nuts and tighten to 24 ft. lbs. (32 Nm).
  4.  
  5. Connect the pedal pushrod and brake switch.
  6.  
  7. Connect the vacuum hose to the booster.
  8.  
  9. Adjust the booster pushrod.
  10.  
  11. Install the master cylinder and combination valve bracket to the booster studs, then secure using the retaining nuts.
  12.  
  13. Connect the negative battery cable.
  14.  
  15. Start and run the engine, then check for proper booster operation.
  16.  

ADJUSTMENTS



Pushrod
EXCEPT HOMBRE

See Figures 2 and 3



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Fig. Fig. 3: Adjusting the pushrod length

Before installing power brake booster, check the distance from the flange face of the booster to the end of the pushrod. Projection should be 0.709-0.717 in. (18.0-18.2). If adjustment is needed, rotate the shaft until the correct length is reached.

The procedure for measuring involves the use of a pushrod gauge (tool J-34873 or equivalent.)

  1. Set the pushrod on the master cylinder end, and lower the pin until the tip slightly touches the master cylinder piston.
  2.  
  3. Turn the gauge upside down and set it on the power brake booster.
  4.  
  5. Adjust the brake booster pushrod length until the pushrod lightly touches the pin head.
  6.  

HOMBRE

See Figure 4



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Fig. Fig. 4: Measure rod length-Hombre

To adjust the booster pushhrod:

  1. Apply 25 in. Hg (85 kPa) of vacuum using a hand held vacuum pump or apply maximum engine vacuum.
  2.  
  3. Check the maximum and minimum rod lengths using J-37839 or an equivalent pushrod height gauge.
  4.  
  5. If the piston is not within limits, install a service adjustable piston rod and adjust it to the correct length.
  6.  

 
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