Red Hot


#1

I posted a simmilar bulletin about a month ago. This problem deals with the brakes on my 1990 Riviera. About 6 weeks ago, I had a problem where the brake pedal would occasionally develop a deadzone. It would be small, only a short swing, and the brakes would still operate at full strength if fully applied. At first I thought it was just a bubble that was moving between the step chamber, the primary chamber, and the valve. But I noticed that the brakes would stick, even when untouched. At one experience, the car was idling in drive, but with the brake pedal was released, the car didn’t move at all. I verified that all four brakes were applied evenly; all four wheels were uniformly hot to the touch after getting home. I removed the master cylinder and checked the brake booster (which does not have an adjustment, btw) and the master cylinder. The piston was all the way at the back of the pocket, as it would be if the brakes were off, and the booster rod was sitting in the most off of positions too.



The problem went away, but now it’s coming back. It’s intermittent, and I beleive it may have some correlation to hotter outside temperatues. But I suppose the engine compartment is always the same temperature. The problem seems to occure and subside practically of its own will. Last week, I practically couldn’t go a drive without it. This week, it hadn’t happened at all… until tonight.



This time, I had an incident and had to brake hard. I slammed the brakes until they practically hit the floor, ended up locking all four tires and came to a very smelly, smokey stop. It was after that the problem came back. But the brakes weren’t stuck too tough, and to be honest I’ve gotten used to this by now, so I thought nothing of it. But a few minutes later, I noticed that the brake application was getting stronger, and stronger. So I pulled into a park to try and free up the brakes. I pumped them very hard several times, but they stayed stuck. Actually, I made it worse. The brakes got jammed on so hard that I had to limp home in second gear in order to stay moving. It was late, I had no other choice. Barely a mile later I was overheating, and the brakes were smoking worse than a locked tire. The front left rotor was glowing bright red, and the rest were simmilarly as hot. The wheels were impossible to touch. The brakes would not unstick for all the pumping that I could muster on the pedal. I hit the front of the master with a hammer, didn’t help. However, as soon as I unbolted the master, everything was normal. The pistson was sitting idle, and the booster rod was not extended at all. I put everything back together, and the brakes felt fine and normal. It was dark, so I haven’t determined the damage to calipers, rotors, and pads.



My questions:



Is there any way that this could NOT be the master?



If it is, which I’m fairly certain it is, this will be the second replacement master cylinder for this car that has had to be retired. The first was a reman Cardone unit. This is a brand new cardone unit, supplied out of good faith since the reman unit went bad. Another bad master? What should I be asking for? Should I demand another brand? Another new master from Cardone? Maybe even a professional installation since this’ll be the third replacement I’ve had to undertake?



Finally, there’s a good chance that other brake parts were damaged. The pads were almost certainly heavilly worn; what wasn’t worn off while driving home was probably converted to smoke, but I haven’t gotten to look yet. Also, rotors glow at what, 900?F? Iron becomes pretty malliable at that temperature, and the brakes were applied fairly tightly in one sitting position. It’s a good chance that the rotors are toast. Other damages could show up after inspection. Should I be demanding that Cardone furnish parts and any necessary labor or other costs to remedy any problems resulting from this experience?



I would REALLY appreciate some opinions here! I’ll be calling Cardone on Monday. I figured it’d be most professional to wait until the start of the business week.



-Matt


#2

I also suspect the Master, but only because all four corners locked-up. Usually, if a single corner locks up, I’ll replace the caliper/cylinder and the rubber flex hose. These rubber hoses can, after time, degrade inside and out. An inside degradation could develop into a condition where the hose acts like a check valve, blocking brake fluid from releasing the brake. But, like I said, with all four corners affected, I suspect the Master.


#3

Sounds like the pressurized fluid cannot go back to the reservoir when you release the pedal. I suggest you check the master cylinder alone, it is possible it has clogged bypass-hole connecting to the reservoir.

Also this could happen if you install a lip seal onto the piston of the master in the wrong direction(I doubt it, though).


#4

Hoses are all new, in case anyone is curious.

-Matt


#5

Well, you’ve done some damage that’s for sure. Ok, to start with, the comment about checking the master cylinder for a plugged orifice is a great place to start.

But since your adventure in driving home, I would completely replace all the brake fluid at a minimum. You really heated it up bad. Second, check out all the pads to see if any or all need replacing. Same goes for the rotors. Finally, check each caliper and consider rebuilding or replacing. The high temps they saw could have degraded/damaged/destroyed the seals in there. Unfortunately, could be an expensive fix.


#6

I’ve figured as much. My real question is whether or not Cardone is responsible. It’s their master that failed.

-Matt