Vacuum Pumps Pontiac 6000 I

DESCRIPTION & OPERATION

Three different types of vacuum pumps are used; an electrically-operated pump, an alternator-driven mechanical pump and a belt-driven mechanical pump. Not all engines of a particular size will use a pump, as it depends upon the model and accessories. Vacuum pumps are used to operate power brake units on most models. Some pumps may be used to operate accessories.

Used on 2.8L V6 and 4.1L V8 engines, pump is mounted under battery tray on right side (Eldorado and Seville) or left side (all others) of vehicle. Inlet hose is connected to booster check valve; outlet hose connects to intake manifold. A warning light switch is located in inlet hose and turns brake warning light "ON" when vacuum drops below a specified level.

A charcoal filter in outlet hose protects pump from vapors. Pump used on 2.8L V6 engine has an internal switch in controller to activate pump when power brake vacuum drops below 12-15.7 in. Hg. Pump used on 4.1L V8 engine runs whenever the ignition switch is on. Pump can only be operated with ignition key in "RUN" position.

ALTERNATOR-DRIVEN MECHANICAL PUMP

The alternator-driven pump is used on 1.8L diesel 4-cyl. engines. Pump is installed on rear of alternator and driven by alternator rotor shaft.

BELT-DRIVEN MECHANICAL PUMP

The belt-driven pump is used on 3.0L V6 engine. The pump has a pulley attached which turns a shaft inside the pump that operates a cam, which in turn operates a spring-loaded diaphragm within the pump. A warning light switch is located in vacuum hose next to power brake vacuum booster and turns brake warning light "ON" when vacuum drops below a specified level. Pump is serviced as an assembly ONLY.

ALTERNATOR-DRIVEN PUMPS

1. Install a vacuum gauge to inlet port of vacuum pump. With is installed on rear of alternator and driven by alternator rotor shaft.

Scheme 87

1. Remove vacuum hose from inlet port and plug opening. Install vacuum gauge to inlet port. Block drive wheels, apply parking brake, and place auto. trans. in "PARK" or man. trans. in "NEUTRAL".
2. Start engine and operate at idle while watching vacuum gauge. After 30 seconds, gauge should read 21 in. Hg; if not, check for vacuum leaks, drive belt tension, and idle RPM before replacing vacuum pump. (Scheme 87): Belt-Driven Pump Test Connections Step 3) uses this connection. Steps 1) and 2) connect gauge directly to inlet port. NOTE: For problems of excessive brake pedal effort, or if the brake warning light is "ON", check for vacuum leaks, drive belt tension or idle RPM.
3. Reconnect outlet hose (if removed). Connect inlet hose. Place vacuum gauge with a "T" fitting in inlet hose between pump and accessories. (Scheme 87) With engine idling, wait one minute and check vacuum. If reading is not less than 18 in. Hg, pump is okay and fault is not with vacuum system.
4. If vacuum is still low, check all attaching hoses for leaks. If still low, check all vacuum operated accessories for leaks or bad connections and repair or replace as required.

ELECTRICALLY-OPERATED PUMPS

Note. For problems of excessive brake pedal effort, or if the brake warning light is "ON", the following test should be used.

Scheme 88

1. Turn ignition on. Remove wiring harness from motor and check for 12 volts at terminals "A: and "B". Check for good ground at terminal "D". (Scheme 88) If 12 volts is not present or ground not good, repair as required. (Scheme 88): Electric Vacuum Pump Terminals Terminals located on controller portion of pump.
2. Connect 12 volts to terminals "A" and "B". Ground terminal "D". If pump does not operate, go to step 3). If pump operates, go to step 4). NOTE: Pump should not draw more than 8 amps in steps 1) and 2) nor leak more than 2 in. Hg in other steps.
3. Remove vacuum pump from vehicle. Check for stuck brush, shorted brush or broken wires in controller. If defects are found, repair as required. If no defects, replace controller.
4. Turn ignition off. Remove inlet hose and attach hand vacuum pump to inlet. Turn ignition on. If pump runs intermittently and will not hold steady vacuum, go to step 5). If pump runs, then shuts off within 5-10 seconds when vacuum reads 10-15 in. Hg, pump is okay and a leak exists in other parts of system.
5. Remove pump from vehicle. Remove controller assembly and "T" connector from inlet hose-to-outlet hose housing. Attach hand vacuum pump to inlet port and draw 20 in. Hg. If vacuum holds, go to step 6). If vacuum leaks down more than 2 in. Hg per minute, replace controller.
6. Attach hand pump to housing inlet and draw 20 in. Hg. If vacuum holds, go to step 7). If vacuum leaks more than 2 in. Hg per minute, replace umbrella valve.
7. Plug pump inlet port, attach hand pump to outlet port and draw 20 in. Hg vacuum. If vacuum holds, pump is okay and no further checks are required. If vacuum does leaks more than 2 in. Hg per minute, check outlet housing bonnet and recrimp, if necessary. If vacuum holds, pump is okay. If vacuum still does not hold, replace piston assembly inside bonnet.

Pump Runs Continuously

1. Check all attaching hoses for leaks. Repair as required. With ignition off, remove inlet hose from pump and connect hand vacuum pump to inlet. Turn ignition on. With 10 in. Hg applied, if pump continues to run, replace controller.
2. If pump shuts off when vacuum reaches 10-15 in. Hg, drop vacuum back to less than 10 in. Hg. Pump should run until vacuum reaches 10 in. Hg, then shut off after 5-10 seconds. If so, pump is okay.

4.1L V8

1. Remove vacuum hose from inlet port. Install vacuum gauge to inlet port. Turn ignition on. After 10 seconds, gauge should read 21 in. Hg. If necessary, replace pump as an assembly.
2. Connect a 0-20 ammeter in series to vacuum pump wiring. Block the pump intake. Operate vacuum pump and ensure current draw is less than 8 amps. If necessary, replace pump as a unit.

Removal

Raise vehicle and remove splash shield on left side only. Disconnect hoses and electrical connector at vacuum pump. Remove 3 nuts securing pump to mounting bracket and remove pump.

Installation

To install, reverse removal procedures.

Electric Vacuum Pump Mounting (2.8L V6 Shown; 4.1L V8 Similar). Scheme 89

Remove oil lines, vacuum hose, and mounting bolts from vacuum pump. Hold center plate and remove vacuum pump from alternator shaft.

1. Position rotor with serration boss turned "UP" on center plate housing. Align holes of center plate with rotor (ensure "O" ring is not projecting beyond center slot). Using mounting bolts, install vacuum pump to alternator.
2. Install oil lines and vacuum hose to vacuum pump. Pour oil (5 cc) through filler port and ensure alternator turns freely.

Alternator-Driven Vacuum Pump Mounting. Scheme 90

Removal & Installation

Loosen belt tension. Remove vacuum hoses, pump-to-mounting bracket attaching bolts, and remove pump from vehicle. To install, reverse removal procedure.

Belt-Driven Pump Mounting (3.0L). Scheme 91

OVERHAUL

Note. If belt-driven or 2-wire electric vacuum pumps are found to be defective, they must be replaced as an assembly.

Removal & Disassembly

Remove oil lines, vacuum hose, and mounting bolts from vacuum pump. Hold center plate and remove vacuum pump from alternator shaft. Carefully separate.

1. Check length of vanes. They should be .511-.531" (13-13.5 mm). If not, replace vanes. Measure inside diameter of housing. It must be 2.244-2.248" (57-57.1 mm). If not, replace vacuum pump.
2. Using a screwdriver, apply light pressure to check valve. Observe if it operates smoothly. If not, replace check valve.
3. Observe oil seal for wear and inner face of rear housing for oil leakage. If necessary, pry oil seal from rear housing and install a new one.

Installation & Reassembly

1. Position rotor with serration boss turned "UP" on center plate housing. Align holes of center plate with rotor and install vanes in slits of rotor. (Install vanes with chamfered sides outward).
2. Ensure "O" ring is not projecting beyond center slot, install rotor assembly (Be careful not to scratch vane contacting surface of housing.). Using mounting bolts, install vacuum pump to alternator.
3. Install oil lines and vacuum hose to vacuum pump. Pour oil (5 cc) through filler port and ensure alternator turns freely.

Controller Assembly & Disassembly

1. Remove tie bolts holding together body, pump housing and rear housing. Remove rear housing. Do not damage "T" connector. Remove self-tapping screws holding controller to rear housing.
2. Detach brushes from brush holder and remove controller. Remove old gasket.

Exploded View of Electric Vacuum Pump Housings are serviced as complete assemblies ONLY. Scheme 92

Reassembly

1. Replace controller assembly, using new gasket and washer. Ensure both brushes are located in brush holder cavity of rear housing. Install brush springs, placing one end in slots above spring access holes.
2. Place brushes in brush channels ensure shunts are routed properly. Place brush retainer in preassembly position and return spring to load condition. Install rear housing. Install tie bolts holding body pump housing and rear housing together.

Piston Assembly & Disassembly

Uncrimp tabs on bonnet. Pump housing and bonnet must be held together during disassembly due to spring load on bonnet. Remove bonnet and spring. Lift piston assembly out of pump housing. Remove and replace umbrella valve assembly.

Replace piston assembly and spring. Place bonnet on spring and compress. Crimp tabs on bonnet, allowing no tolerance for movement between bonnet and pump housing assembly.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS