UPDATE: Just rechecked and when i press the brakes with car on, I can hear a hissing sound like air going out of a tire from the left side of car and brake pedal slowly sinks to floor, the car idles higher. When I release the brake pedal, the idle returns to lower. Also the clicking sound is actually coming directly from the gear shift, not the passenger tire.


Hello.

1) Just got 91 Accord LX with 190,000 miles for my son's first car (and my first time owning/working with a Honda.) Fortunately I drove it for a day and discovered Brakes issue by bumping a car parking in a lot when brakes failed. They seemed to be working fine then pedal started to really sink and braking was very slow to happen.

2) Symptoms: Zero noise in the pads (screeching), zero brake warning lights of any kind on, the reservoir is completely full of brake fluid, I do not see an ABS resevoir. I hear a clicking noise when in driver's seat to do the tests I found in this thread https://honda-tech.com/forums/honda-...ssure-3338859/ The clicking comes from the front passenger tire area when I press the pedal lightly the gear shift. It is very clear loud click, click with each light press of the pedal with the engine off. I will put the results of the suggested tests in the thread below in red ink. I don't know if I should just put a master cylinder on, bleed and see if it fixes problem. I don't really want to just throw that at it without trying to discern some what it is exactly.

THANKS in advance very much for any suggestions.

From the thread:
"This information is from my service manual under BRAKE BOOSTER INSPECTION:

Functional Test
1. With the engine stopped, depress the brake pedal
several times, then depress the pedal hard and hold
that pressure for 15 seconds. If the pedal sinks, the
master cylinder, brake line or a brake caliper is
faulty. There is a very small amount of sink after the 15 seconds. I was hoping for a very detectable sink and just replace the master cylinder, but it was not super clear as it only slightly sinks.

2. Start the engine with the pedal depressed. If the pedal
sinks slightly, the vacuum booster is working. If
the pedal height does not vary, the booster or check
valve is faulty. Yes there was a slight sinking upon starting the engine indicating booster okay. This was confusing as other tests indicated not okay. For this, there was a definite sinking upon start.

Leak Test
1. Depress the brake pedal with the engine running,
then stop the engine. If the pedal height does not
vary while depressed for 30 seconds, the vacuum
booster is OK. If the pedal rises, the booster is faulty. This test however indicated faulty as there was a definite rise in pedal after turning the engine off. So first test said good, this one indicated bad.
CAUTION: Do not try to disassemble the booster.
Replace the booster assembly with a hew one.

2. With the engine stopped, depress the brake pedal
several times using normal pressure. When the pedal
is first depressed, it should be low. On consecutive
applications, pedal height should gradually rise.
If the pedal position does not vary, check the booster
check valve. There was a gradual rise in pedal height on this test indicating booster okay again.

Check Valve Test
1. Disconnect the brake booster vacuum hose at the
booster.
2. Start the engine and let it idle. There should be vacuum
available. If no vacuum is available, the check
valve is not working correctly. how do i check that there "should be vacuum available"? Do I put my thumb over the hose to see if it has vacuum pressure?
Replace the check valve and retest."

Thanks again for any help with finding which part of the brake system could be trouble here.

 

Just took a drive to try to get a better idea what it's doing and saw that:

1) It idles high when I press the brakes ONLY in Park. When it is in gear- no change in idle.

2) I hear the hissing sound the entire time I am pressing on the brakes. It never stops hissing when I press the brakes.

3) It seems like the pedal is soft at initial press, but then maybe becomes harder. So seems like not booster because the pedal isn't rock hard. It does seem to sink when I am pressing it as hard as I can with two feet, hearing the hissing sound and hoping it will stop, but very slowly and definitely not to the floor.

4) With all of the testing and brake pumping, there has been no change in the brake fluid in reservoir.

5) I only hear the clicking sound at the gear shift when I press the breaks when the ignition is OFF. No clicking sound when key turned on.