I have a 1993 six speed unmolested all orginial 14,000 mile coupe . I'm looking for help in determining whats wrong before i buy a bunch of parts I don't need to.. Start car up and hit brake pedal goes almost to floor and brake light comes on. Pump it a coupla times comes up solid and holds good. take foot off brake and let idle for 5 min goes almost to floor again, Pump again and solid! afraid to drive it til i get it figured out.. also i used to have a 1989 coupe and i could hear the abs unit in rear floor making sounds when i first started car, but i hear nothing on this car, didnt know if this one should make sounds too, but dont remember hearing this 93 do sounds. no leaks at all under car, would booster vacuum loss cause this? would mater cyl cause this? would check valve on where vacuum hose goes into booster cause this? Or should i cut holes in the floor board so I can drag my feet? lol any help appreicated!! Oh another thing different subject, when car is in nuetral and your rev engine slightly you hear a slight rattling in what sounds like exhaust anyone know what that might be?

 

Probably gunked up ABS. do a flush.

 

Do you hear any hissing while pushing the brakes?

the boosters are known to crack due to age and heat.

with the car off, how do they feel? Pump them up and pedal stays firm? Or is it still soft?

 

Agree start with the basics, while 14k is low miles, fluids are affected just as much by age as mileage...if you haven't you should be flushing all fluids in the car.

The rattling might be an exhaust clamp that has broken, need to climb under the car and do a visual inspection.

 

I went through a similar situation on my ‘96 this spring. Started by bleeding the system, no change. Replaced the master, no change. Cycled the solenoids in the ABS unit, fixed! If I could go back in time I would bleed the system and then cycle all the solenoids. I am going to bleed the system and cycle the solenoids every couple years as a maintenance item. Good luck and let us know what you find.

 

Postcar,

I have a 93 A4 that was pretty rough that had 140k on the clock, funny seeing the other end of the spectrum!

After 28 years, a lot of stuff on this car is getting old and ready to be changed. My ideas from cheapest to most expensive:

1. Inspect the vacuum hose for any cracks or leaks. GM used high quality rubber hoses, but it is worth checking due to age.

2. Flush the brakes! This issue sounds like you may have air in the system. Even if you don't, this fluid should be changed every 2 years to maintain seals in the braking system, as well as maintain effectiveness of the fluid. You can bleed the ABS separately, or bleed all 4 calipers, go out and stomp on the brakes until the ABS functions and then bleed the calipers again to get all the old fluid out
2a. Inspect the flexible brake hoses and the fittings for any leaks. Even if none are present, the original hoses would be 28 years old and could be a safety hazard!

3. The brake booster is also potentially 28 years old. I just changed mine out last Friday, looks a lot worse than it actually is. You can "Test" the check valve by getting a length of tubing and blowing into it. It shouldn't allow you to blow into it, but to suck air out of it.
NAPA Online was the only place I was able to find a brake booster, just in case this is the issue.
The plastic could get brittle and crack with age, inspect the housing as well.

Good luck! Brakes can be a pain, but they're worth having in tip top shape.

 

How do you flush it out?

 

How do you cycle the solonoids?? thks

 

Probably the best $129 I spent on the only chevy dealer service I have done so far. brakes flush service.

 

Does the dealership cycle the ABS too?

 

If you have to ask that question, then I highly advise you reach out to your local car mechanic and ask how much to flush/change all fluids in the car including brakes.