Brake vacuum assist

[lawrencedesigns]

My brake pedal lately has been very heavy, and after a few applications it releases, softens, and seems normal.
Today I noticed that it remained very heavy, as if the vacuum assist has stopped.
I understand there is a valve in the system that perhaps needs to be freed up.. Where is the dang thing? And how does one get it out?

Keeth Lawrence
84 Spyder

[papajam]

The older standing pedal Alfas have the metal check valve screwed into the #4 cylinder intake tract. Not sure where the newer models have theirs but most manufacturers have the plastic check valve at the booster. It's a 90 deg. elbow that pushes into a rubber grommet on the booster side and the vacuum hose to the engine is on the other.

[John M]

Papa is right. Valve on the later cars is still on the intake manifold coming from cylinder 4. Follow the brake booster hose from the booster to the engine and you will find the valve. Probably not the problem. The elbow on the booster will also twist and come off the booster. That might allow you to inspect the inside of the booster to see if the master cylinder is dumping brake fluid into the booster. If so....brake fluid will ruin the inner seals of the booster resulting in failure of the booster. Also check your booster hose. Do you hear a hissing that sounds like a cho cho train when you depress brake? Try to locate any sounds to determine location of your trouble.

Best Regards,
John M

[Keven]

Here's a quick way to check if the servo is the problem. Once you have verified that
that the vacum line is properly attached, place your foot on the brake pedal with the
car off, keep your foot on the pedal, and start
the car. The pedal should move slightly down when the car starts, if not you have a dead servo.

Dont think you can rebuild a ATE servo, so if it is out, you'll be out $300!!

John is absolutely right about the brake fluid ruining the servo, it happened to me.
If it is leaking into the servo, a telltale sign is the paint peeling where the bake master
cylinder attaches to the servo.
I no longer wait for the master cylinder to go, I simply rebuild it every 50K miles or so.
Also flushing your brakes out every two years does wonders to prolong brake parts life.

[Favali]

Before you start the car, you need to pump the pedal 4-5 times ... then hold your foot lightly on the pedal with a steady pressure then start the car.

If the pedal drops when the car starts, the booster is working. If it remains stationary or actually moves towards you, the booster needs replacement.

If you have fluid leaking into the booster belly you can suck it out with a turkey baster but it will still fail in time.