Hey Everyone - scary thing happening and crowdsourcing here for help

Bought an 87 with 60k miles about a year ago, been driving it in suburbia with no problem. Recently the brakes failed in two incidents, both of them were driving on hot days with lots of uphills.

In both cases the brake pedal immediately went to the floor, with no warning. Driving, driving, driving. Boom, no brakes. There was a whining/moaning sound (like a whoopie-cushion) coming out of the brake pedal area for about 40 seconds immediately after the brakes failed. In both instances I waited on the side of the road for 30 minutes and then the brakes magically continued to work phenomenally! I'm obviously terrified that the brakes will fail out of nowhere again...mechanics want to replace everything, but I'm not so sure that's the issue here...

Thoughts?? Some thing I've brainstormed -
1. Boiling brake fluid - it was certainly hot, but didn't appear to be boiling when I checked it in those two instances
2. ABS - I've had an "anti-lock" alert on my error-screen since I bought the car. I was told it was just a weird sensor thing and never had any issues despite this being lit-up. But could this be indicative of what the problem really is?
3. Caliper locked? How can I tell?
4. Master Cylinder?
5. Bleed the brakes - given the symptoms (brakes work super well almost all the time), is this really relevant?

Thank you all in advance!!!

There were some ideas here but nothing concrete that matched my symptoms exactly -
https://www.corvetteforum.com/forums...-to-floor.html

 

If you have never bled them then, yes it is relevant. Does your ABS activate correctly? Test it at low speed on a gravel road. Do this numerous times before bleeding. Water in the brake fluid boils way before the brake fluid. Dan

 

Forget the cost. Unless you want to kill, or be killed, take your vette to a brake shop now.

 

An option would be to overhaul the entire brake system, I see it as an opportunity to refresh the entire system, caliper overhaul, master cyl replacement, new pads, new rotors, check the wheel bearings, new fluid, new caliper hoses etc.
THE PROBLEM with this is idea (and the others that have replied) is the ABS. You can and should research the threads on this site about ABS. It is appx $1200 to have it repaired. You could replace it with a proportioning valve as your corvette has the 2nd generation Bosch system which is 3-channel and some say not very good. It is not the caliper locked up as you would not have the pedal go to the floor.

You have to weigh, if you can fix it yourself vs the expense of having someone else do it. I envision someone else doing the job and taking it around the block and saying "brakes work" only to have this rare event still occur later. I do not know of anyone anywhere that does not own and work on their own C4 that could possibly be trusted to fix early C4 ABS problems. When a hydraulic mechanism looses pressure, it is because pressure has been released.
1. Are you loosing fluid ??? is the fluid level down.
2. That moaning, was it the ABS motor running ?? Isn't this a giant hint ???
3. Did the brakes come right back and work ??
4. How old are the components in your brake system??
5. Taking it down to "Charlie" at the brake shop is ludicrous.


Some have said before that pulling the fuse on an ABS system fully disables it. You will have to research this forum on your own to find out what that does and make that decision on your own.

 

I'm thinking the master might have an intermittent stroke though, when hot fluid is probably thinner and slides around tired seals

 

Yes you have boiling brake fluid. It may not have been boiling in the master cylinder but was at the wheel cylinder. Replace the fluid and the caliper seals. Caliper seals can harden due to age and cause the brakes to drag.

 

If its of any comfort, with a partial failure (single hydraulic circuit failure) you should still be able to stop within 456 ft from 60 mph (FMVSS 105). Double circuit failures are rare. If you should happen to break the brake pedal itself or the booster input pushrod, you're kind of screwed. I'd start with fresh brake fluid and a good bleeding. Contaminated fluid can cause some bad things to happen. Ensure that you're able to get fluid to flow from all 4 calipers when bleeding.

 

'87, stock anyway, has drum-based parking brakes that are wire activated, so keep in mind to grab that park lever if you have to.
I expect earlier are as well, not sure when (or if) the drum brakes were removed in later years.