Brake diagnostic problem - Toyota Nation Forum : Toyota Car and Truck Forums

egol · 12-28-2005, 12:41 PM

I'm having a problem with the brakes on my 1999 camry L4. When I breake, the pedal goes almost all the way to the floor. I have adjusted the brakes in the back and a round of bleading, but no change.

I notice when I apply constant pressue when breaking, the pedal goes lower and lower until it hits the floor. Also when pumping the breaks the pedal goes higher and higher but slowly down again until it hits the floor (like deflating a ballon). Now the question is if this point towards the Master Cylinder leaking or the Brake Booster?????

So for all you experts out there what do you suggest I look at first?

somick · 12-28-2005, 01:14 PM

I do not think that the brake booster may leak. It just enhances your braking power.
According to the conditions you've described you have a major system leak. Be carefull. DO NOT drive! Trace all the lines and I am sure you'll find it.

Sam

internetautomar · 12-28-2005, 01:24 PM

sounds like the master cylinder to me

egol · 12-28-2005, 01:28 PM

Thanks for the input. The system in itself is not leaking as I'm not adding fluids. The symptoms are quite consistent in its behavior

internetautomar · 12-28-2005, 01:34 PM

the master can have bad seals that allow fluid to go where it isn't supposed to and in the process cause a mushy pedal.
it's the first thing I'd replace, usually pretty cheap, and easy to do.

Cyorke · 12-28-2005, 02:08 PM

^^^ I ahve to agree. It sounds like the seals inthe amster cylinder are shot and not allowing the fluid to pressureized. IT is jsut going back inot he master cylinder around the seals. The seals look like plungers more or less and when they go bad the loose thier sealing ability. The brake fluid ends up getting by the plungers. Try replacing the master cylinder and rebleeding the brakes.

egol · 12-28-2005, 02:44 PM

So is it worth trying to just replace the seal or should I just replace the whole Master Cylinder to avoid further problems?

Cyorke · 12-28-2005, 03:05 PM

You can try rebulding the master cylinder but by the time you do that and put the time into doing it you could have probably bought a new one and installed it and only cost a little bit more money. Rebuild kits are not really expensive but you have your time involved in rebuilding it. How much is your time worth. Also if for some reason it doesnt work correctly then you probably ownt have much of a warranty on the parts. Whereas on a new master cylinder you should have some kind of warranty if it were to fail again.

Just loking on Autozone.com there are no master cylinder kits available through them. I am sure you could find osmeone that has one but if it were me I would jsut replace it instead of rebuilding it. Like I said youget warranties on new parts if you gea kit you amy not.

internetautomar · 12-28-2005, 05:00 PM

Quote:

Originally Posted by csaxon

You say you replaced your rear shoes (Iassume not pads) and bled the system. I suspect your rear shoe clearance is out of adjustment and you may have air in your brake system. Check your bleed valves are snug. Do you have ABS?

How were your brakes before the change?

air normally causes a spongy feel in the pedal

rebuilding a master sounds simple, but if there's damage inside (IE bore out of round) you'll have to get a new/rebuilt t one anyhow
A-1 cardone rebuilts only have a list of $138

Gary_602Z · 12-28-2005, 07:33 PM

Master cylinder. A lot of places do not sell rebuild kits any more.

Gary

internetautomar · 12-28-2005, 07:46 PM

Quote:

Originally Posted by csaxon

internetautomar "air normally causes a spongy feel in the pedal"

Good answer, however the 1999 factory manual for his car says for the symptom of a "low pedal" among the causes are omg! AIR in the Brake System and Rear Brake shoe clearance out of adjustment!

PS It's a good thing we don't see your sig, you'd probably go out of business.

must be the configuration of the MC, I've driven a few cars with shoes out of adjustment and the pedal felt fine, stopped like crap but the pedal felt fine.

My business is more primarily maxima related, and most max's came with rear disc

Dave's · 12-28-2005, 08:09 PM

off the wall possibility- flexible hoses can sometimes become weak before failing completely. They can swell like a balloon under pressure and then deflate when brake is released. Brakes will act pretty much as described although constant pumping usually will cause it to leak or even burst. (But it's probably the master cylinder.)

egol · 12-28-2005, 08:34 PM

Thanks all for your input. Regarding the rear breakes then they seem to work fine (on their own). The emergency brake takes were it is suppoesd to after I adjusted the rear breaks (drumbs). There was a slight improvement after adjusting and bleeding the breaks, but Im still able to press the pedal to the floor if I press hard enough.

Note, the car will break and stop. I still drive it from time to time.........

I think I will go with a new Master Cylinder.

internetautomar · 12-29-2005, 07:03 AM

nice procedure, just be careful when you clamp the hoses not too damge then at all

Digger1 · 12-29-2005, 10:29 AM

Egol,

My $$'s on the master cylinder.

You probably know this already, but after you get 'er working again, it wouldn't hurt to change the brake fluid every now and again. I change mine every 30K miles.

Be sure and let us know what the problem was when you find it.