1987 Honda Prelude 4 cyl Front Wheel Drive Manual 235000 miles
I experienced a hard brake pedal yesterday. I started to smell the brakes while driving. Stopped the car to inspect and all my rims were hot to the touch. Brakes appear to be applied slightly without touching the brake pedal. Since it's all 4 tires I'm guessing it may not be calipers. I'm thinking it might be something to do with the booster or master cylinder. Is there a cost efficient way to test this or should I bring this in or could I be in left field alltogether.
Lack of power assist may be due to low engine vacuum, a leaky vacuum hose or a defective booster. Sometimes a faulty check valve will allow vacuum to bleed out of the booster causing a hard pedal when the brakes are applied. This condition can be diagnosed by starting the engine (to build vacuum), shutting it off, waiting four or five minutes, then trying the brakes to see if there is power assist. No assist means a new check valve is needed.
A quick way to check the vacuum booster is to pump the brake pedal several times with the engine off to bleed off any vacuum that may still be in the unit. Then hold your foot on the pedal and start the engine. If the booster is working, the amount of effort required to hold the pedal should drop and the pedal itself may depress slightly. If nothing happens and the vacuum connections to the booster unit are okay, a new booster is needed (the vacuum hose should be replaced, too).