Power Brake Booster - Vacuum Leak Test Procedure
83chrysler9Models
All Domestic Passenger Cars & Trucks With Vacuum Operated Power Brake Booster
Subject
Power Brake Booster Vacuum Leak Test Procedure
Index
BRAKES
Date
August 8, 1983
No..
05-01-83
P-2757-C
The following leak test is to be performed when diagnosing power brake or vacuum leak related driveability complaints. This procedure replaces only the "power brake" vacuum leak tests in the 1983 and prior service manuals.
SET-UP PROCEDURE
1. Remove the A/C vacuum control line (if so equipped) from the booster check valve. Cap off the nipple.
2. Remove the vacuum hose or rubber cap from the speed control outlet nipple on the booster check valve. If the booster has no speed control outlet nipple, see note below.
3. Attach a vacuum gauge to the speed control nipple on the booster check valve. Plug any remaining open nipples.
NOTE: SOME TRUCK BRAKE BOOSTER CHECK VALVES DO NOT HAVE SPEED CONTROL OUTLET NIPPLES. IN SUCH CASES, TEE THE VACUUM GAUGE HOSE INTO THE VACUUM SUPPLY HOSE NEAR THE BOOSTER.
LEAK TEST - BRAKES APPLIED
1. Use the set-up procedure, steps one through three.
2. Start the engine. Allow a warm-up period so that the fast idle speed adjustment screw comes off the fast idle cam.
3. Apply light effort (approximately 15 pounds of pedal force) to the brake pedal and hold steady in this position. DO NOT MOVE THE PEDAL from this position as it will affect the leakage reading.
4. Using vacuum line pliers (tool number C4390), have an assistant close off the vacuum supply hose to the brake booster. Allow five seconds for stabilization and observe the vacuum gauge. Vacuum drop should not exceed 3.0 inches Hg in 15 seconds.
5. If vacuum drop exceeds specifications in this test, repeat the procedure to confirm readings. If the leakage rate repeats, the booster is defective.
CAUTION: DO NOT USE VISE GRIP PLIERS OR ANY OTHER TYPE OF CONVENTIONAL PLIERS TO PINCH OFF THE VACUUM SUPPLY HOSE TO THE BOOSTER. DAMAGE TO THE HOSE AND/OR A FALSE LEAKAGE READING WILL OCCUR. ALWAYS USE SPECIAL VACUUM HOSE PINCH OFF PLIERS (TOOL NUMBER C4390). IF C4390 IS UNAVAILABLE, USE A 3/8" PIPE THREAD GAS VALVE AND TWO INTAKE MANIFOLD VACUUM NIPPLES PLACED IN THE SUPPLY HOSE FOR THE TEST. BE CERTAIN THAT THE VACUUM GAUGE AND SHUTOFF VALVE DO NOT LEAK, OR TEST RESULTS WILL NOT BE ACCURATE.
LEAK TEST - BRAKES NOT APPLIED
1. Use the set-up procedure, steps one through three.
2. Start the engine. Allow a warm-up period so that the idle speed adjustment screw comes off the fast idle cam.
3. With vacuum line pliers (Tool Number C4390), close off the vacuum supply hose to the booster. Vacuum drop should not exceed 1.0 inch Hg in one minute. If vacuum drop exceeds specifications, repeat the procedure to confirm readings. If the leakage rate repeats, the booster is defective.
POLICY: Information only