Hyundai Coupes/Sedans 1986-1993 Repair Guide

Power Brake Booster

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LEAK TEST



To test the booster for a leak, proceed as follows:

  1. Operate the engine at idle with the transmission in Neutral without touching the brake pedal for at least one or two minutes.
  2.  
  3. Turn off the engine, and wait one minute.
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  5. Test for the presence of assist vacuum by depressing the brake pedal and releasing it several times. Light application will produce less and less pedal travel, if vacuum was present. If there is no vacuum, air is leaking into the system somewhere.
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  7. Pump the brake pedal (with engine off) until the supply vacuum is entirely gone.
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  9. Put a light, steady pressure on the pedal.
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  11. Start the engine, and operate it at idle with the transmission in Neutral. If the system is operating, the brake pedal should fall toward the floor if constant pressure is maintained on the pedal. Power brake systems may be tested for hydraulic leaks just as ordinary systems are tested, except that the engine should be idling with the transmission in Neutral (manual) or Park (automatic) with the wheels blocked throughout the test.
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REMOVAL & INSTALLATION



See Figures 1, 2 and 3



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Fig. Fig. 1: Power booster assembly-1986-89 Excel



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Fig. Fig. 2: Power booster assembly-1990-93 Excel, Elantra and Scoupe



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Fig. Fig. 3: Power booster assembly-Sonata

  1. Disconnect the negative battery cable. Slide back the clip and disconnect the vacuum supply line at the brake booster. Pull gently in order to avoid damaging the check valve.
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  3. Remove the master cylinder.
  4.  
  5. Disconnect the pushrod at the brake pedal. This requires pulling the lockpin out of the pedal clevis pin and then pulling the latter out of the pedal lever and clevis rod.
  6.  
  7. Remove the mounting bolts and nuts from the firewall and remove the booster.
  8.  

To install:
  1. Installation is the reverse of the removal procedures. Install the brake booster on the firewall and tighten the mounting nuts to 10-12 ft. lbs. (13-17 Nm) for Scoupe or 8 ft. lbs. (12 Nm) for the remaining models. Bleed the brake system.
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