: 1983 cadillac 2 door brougham 4.1L V8 vacuum pump

05-25-13, 01:50 AM
can someone explain to me when the vacuum pump needs to be replaced? Keep in mind I have the OEM vacuum pump. Pump has never been replaced. My car has 243000 original miles. What are the symptoms of a bad vacuum pump? is there a write
up on how to replace the pump? Will you recommend oem or aftermarket part? what company and from what store?

05-25-13, 02:03 PM
From my understanding the vacuum pump is just for the brake booster. So the brakes will start weakening and the brake light should start illuminating occasionally as the vacuum pump starts failing.
To replace it you'll need to get a pulley puller unless the new pump comes with a new pulley as well (can borrow them from some part stores) and remove the pulley and bolts and vacuum connection. put the pulley on the new pump and reconnect vacuum. bolt on with the pivot bolt first (leave it loose) and then put pressure on the pump to keep the belt tight and tighten the other bolts. Finally tighten the pivot bolt.
I've never actually replaced my vacuum pump but I've loosened/tightened it taking the belts on and off. It's a bit of a pain to get at some of the bolt heads.

05-25-13, 02:18 PM
thanks I've noticed my brake light come on once in a while. Does this also help with any other vacuum system i have on the car? for example the
cruise control system, emergency brake, etc....

05-25-13, 02:32 PM
The pump is for the brake booster, cruise control, a/c and other.
If the brake light comes up, it has nothing to do with a possible vacuum leak.

If the telltale is on, there are more options:
more probable causes:
- leaking brake line or connection
- air in brake system
- improperly adjusted parking brake

other causes:
- leaking wheel cylinder or piston seal
- leaking master cylinder
- contaminated or improper brake fluid
- faulty automatic adjusters
- restricted brake fluid passage or sticking wheel cylinder piston
- failty metering valve
- faulty proportioning valve
- operator riding brake pedal

If there is a vacuum leak, there is excessive brake pedal effort (like it is at my car (http://www.cadillacforums.com/forums/rwd-19xx-1984-deville-fleetwood-1985/289689-1983-fleetwood-brougham-delegance-project.html))

It is everything described in the '83 Cadillac Service Manual.


05-25-13, 08:44 PM
I was always told a failing vacuum pump would set off the brake light (along with the other possibilities mentioned).
But the big sign is the brakes getting weak (not spongy, but needing to push a lot harder than normal to get the car the stop).