Today as I was driving around(hot as hell out) - my brakes started doing a very strange thing. As I was braking for stop lights and such, it would slowly seem to loose pressure and go all the way to the floor. I could still brake although I had to pump somewhat to get a good solid brake, and it would hold the car in place on an uphill slope, stopped at a light pushed to the floor, but it worries me.
Also, i had my AC on, so I decided to turn it off and test the brakes some more. Well, the 1st couple of times I tested, it pushed slowly all the way to the floor. Then it suddenly seemed like they came back and I had no problems.
Seems strange to me, any solutions? anyone with a similar problem. Much help would be appreciated.
I need to change my master cylinder too. Does anyone know what size the brake line fittings are?
I believe they are 10 mm but I’m not sure. (need to pick up a flare nut wrench)
If you plan to do it yourself, you can do it for around $50. (Remanufactured master cylinder $41 at Pep Boys, a couple cans of new brake fluid, and some tubing for the bleeding procedure).
No problems today which seems odd to me. I believe it MAY be my booster because it was only happening with my A/C on.
Check this scenario and see what you think. I’m 99% sure my IACV is bad and I’m picking up another from a junkyard this weekend. If my IACV wasn’t compensating enough for my A/C being on and braking at the same time, could this make it appear as if the booster isnt quite doing its job very well or is it definitely a master cylinder problem?
Also, last but not least, how do I “check” my booster to see if its good? Is it in my manual? and does anyone have any links on how to change the master cylinder? I might just do it if its only $41? If it seems easy in the manual, I will do it next monday or tuesday, take pics and do another Teg Tip.
i don’ t know much about breaks but i want to learn…what is the master cylinder…and what is the break booster…sorry for the dumb question but i’m curious???
later,
Dan
The brake booster is that large, black circular thing that’s attached to the firewall. It’s connected to the master cylinder. The way I knew it was the cylinder was that I could HEAR the fluid gushing though it. Even with the engine off it was doing it. Have someone depress the brake pedal slowly and see if you hear anything.
I had my booster replaced under warranty so I can’t tell you how much it cost. Man I milked that aftermarket warranty for EVERYTHING it was worth.
It may not necessarily be a problem with the master cylinder or the brake booster. Do you have an after market intake? if so, did you keep your PCV valve? I have the same problem ,but it stems from my intake, I have NO pcv valve. And when my A/C is on, the brakes are “squishy” and will slowly press to the floor. when My AC is off and its not as hot out, they are fine. Check to see if its your PCV valve.
ok ive had this problem, somtimes my breaks are really good, firm pedal somtimes they sink to the floor, how can i check, neil i was kinda cloudy on what u said. If i hear gushy thats good or bad, what needs to be replaced
this is with AC off since mine dont work, and i dont have abs
well under HOT conditions you could simply be experiencing brake fade. possible causes are overheated pads/rotors, rubber brake line expanding, or from simply pressing the brakes too fast over n over again… should check out all the tips from the ealier replies jus to be on the safe side. brake fluid cap(s) are on tight? proper fluid level? have you ever changed the fluid? any brake fluid leaking from calipers, lines, or underhood?
From the sounds of it, it is the Brake Master Cylinder. This is a very, very common problem with our cars. The seals go bad inside the Brake Master Cylinder, causes an internal leak and the pedal to gradually sink to the floor. I have a OEM master cylinder and Goodridge lines sitting here waiting for AEM pads and Brembo rotors.
xenocron, I know your problem. Some days the brakes work fine and some days it doesn’t. Majority of the time the bad side comes up only when your A/C is on. Solution? 99.1% that it’s the master cylinder. Did mines in less than an hour. Just make sure you put a piece of rag underneath the master cylinder or some parts might get soaked with brake fluid.
cdt ryu h - I will check the PCV tomorrow…THANKS!!!
Gerok and everyone else…thanks for all fo the help. Ill update everyone when something works. Does anyone know a good junkyard in Jersey…I am not paying thru m a$$ for this stuff especially since I dont exactly know what the problem is?
picked up a Master Cylinder this morning from Autozone for 39.99 and put it in in under 2 hours…not bad i figure. Seems to have fixed the problem as i went out for a 2 hour drive with the A/C on/off and no brake pedal pushing to the floor anymore, still a bit squishy but hey…maybe now my Booster will go and i can replace that as well — it is an old car right?
Thanks for the help guys…again thank the lord for the G2IC
