No Brakes!

[Taylon]

Hey Everyone,

In my 94 v6, I'm having issues with the brakes. I'm relatively new to this car, so I'm not familiar with all of it's symptoms.

Generally it seems to have more than ample braking power and pressure, but every so often the pedal will suddenly go all the way to the floor. It will still stop, but it doesn't seem to have as much stopping power and it's a very noticeable loss of pressure/pedal position.

The "BRAKE" dash light just came on the other day, so I parked it and switched vehicles.

I don't seem to be losing brake fluid (but again, it's relatively new to me) and since I have adequate brakes most of the time I don't think it's a brake line, but I do suspect it's the master cylinder.... is there anything else I should check? Like an ABS pump or something?


Also, how difficult is it to replace the BMC in these cars? I replaced one in a Ford truck once and it wasn't too bad.


Thanks!


EDIT/ALSO:

If I push semi hard on the pedal all the way to the floor from its usual halfway down position it will lose all of it's pressure and need to be pressed entirely to the floor to activate the brakes. As I write this I'm realizing it's almost a guarantee it's the BMC.

[cocacolagrl]

are you saying your brakes feel low..??????your brakes might be going....or you may need more brake fluid....

does your "BRAKE" light stay on or it came on for a second..went off and hasnt come back on..if so..i wouldnt worry about it..mine did that and my dad checked everything and its been fine...the light never came on again....but..i would get a second opinion...iam no mechanic.lol...but i did have the same experiance as you...

[Larzzzz]

Originally Posted by cocacolagrl

are you saying your brakes feel low..??????your brakes might be going....or you may need more brake fluid....

Never add brake fluid to a system unless you are working on the brakes. The resiviour WILL appear to be losing fluid, but the fluid is actually taking up the space that the brake pads occupied when they were new. The pistons aren't fully into the caliper bore when pads are junk.

Check the fluid level first. If it's really low, chances are that some air has gotten into the system. If that's ok, then pump the pedal like 10x and hold it. It shouldn't go down any further, maybe a tiny bit. If it sinks while you're holding it down, I'd think that the master cylinder is letting fluid past its seals, thus not holding pressure

Does it happen when you slam on the brakes versus, slowing down?. Again, look at the master cylinder.

Pull the wheels off and look at the brakes, bleed the system starting from the farthest wheel, right rear, then left rear, right front, left front.

Good luck,
Larzzzz

[RU2CHKN]

check your brake lines if they have a leak

[96paseo]

Pull your wheels and have a good look at your rubber flex lines. If those are good, check rear wheel cylinders if you have drums and check the master cylinder see if its leaking into the booster.

[Mike Gerber]

In addition to what the others have suggested, also check each wheel for brake drag. If one brake is draging it can get hot enough to boil the brake fluid near that brake. When the brake fluid boils, the bubbles produced can cause the fluid there to compress, rather than transferring hydraulic fluid pressure to that brake. This can cause the pedal to go to the floor, as you have described. Jack up each wheel with the brakes off and try to spin each wheel by hand. See if you feel any drag in a particular wheel.

I too believe you have a bad master cylinder, but check evrything else first before replacing the master.

Mike

[Taylon]

thanks for the replies guys, I will get to it this week. I'll be sure to check all the lines & calipers before changing the MC

[Taylon]

just in case someone searches for a similar problem later, my problem was solved by a new master cylinder.

Pads on my car were all fairly new with plenty of material left on them. BMC was also really easy to replace, just the 3 bolts and bench bleeding and it plugged right in.

2 pieces of advice:
Spend the $6 and buy a flare nut wrench if you don't have one, so much easier than risking stripping the brake fittings. Use a six point socket on the bleeder screws, even though it means not using a hose and dripping fluid everywhere.

Second, make sure to keep bleeding until the fluid runs clear. I stopped before it did this and now that I'm done although I have adequate (and more importantly, consistent) stopping power I can tell there's still a fair amount of air in the lines I'll need to bleed out later.

Hope it helps someone, and thanks to those who helped me!


PS: The "BRAKE" warning light stayed on for about an hour after I fixed the problem, then it went off on its own.