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Brake System Compromised

  #1  
Old 01-28-2012, 06:07 AM
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Default Brake System Compromised

A family member moved my 1990 Camry and may have driven over some rocks which I think caused a rupture in the brake line somewhere.
The reservoir was completely empty of brake fluid.
My question: how do I find the leak?? I filled the reservoir again and pumped the brakes, thinking this might draw the brake fluid into the lines, thus revealing the leak. However, this wasn't the case; the fluid remained in the reservoir.
In the meantime, I'm prepping all the bleeder valves so they'll be ready to go when the time comes to bleed the system (I bought 4 new ones, they're pretty inexpensive @ $1.99 apiece). The first one I tried was seized in there pretty good and it broke off. I tried to get it out with a bolt removal kit but I found it too crowded....I couldn't get the proper angle because there were too many things in the way (strut, etc.).
Today I'm going to attempt to remove the wheel cylinder and fix the bleeder valve that way.
So, my question is: how to get the fluid back into the system so I can locate the leak??
Thanks,

-Mike
 
  #2  
Old 01-28-2012, 10:47 AM
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The brake lines are routed to provide protection against road damage. It would be surprising for one of them to have been damaged by road debris.

Have you checked the usual areas of leakage?

Brake caliper and slave cylinder seal leakage.

Defective master brake cylinder seal causing the fluid to flow into the power brake boaster and be drawn into the engine to be burned.

Flexible brake lines between chassis and brake.

The brake system is split into two systems for safety. The reservoir feeds two master cylinder pistons each powering the brakes on two wheels. If one system fails the other will continue to work.

If the fluid is leaking out where neither of the systems can hold pressure the problem may be the master cylinder.

Even if one brake line was leaking the other system should still be OK and hold pressure.
 
  #3  
Old 01-28-2012, 02:50 PM
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OK, sounds like it might be the master cylinder then. It totally makes sense that it isn't one of the lines that has been ruptured due to running over something (I don't know why I jumped to that conclusion).
There is no pressure at all in the brake system.....I push the brake pedal down and there's nothing. Therefore, you suggest, it's the master cylinder. And it's likely a seal that's deteriorated? Or do I have to replace the entire cylinder?
Many thanks,

-Mike

P.s. Also, the new fluid I put into the reservoir isn't moving into the lines.....is this an indication that it's the master cylinder at fault?
 
  #4  
Old 01-28-2012, 08:05 PM
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If the master cylinder ran so low on fluid that air was able to get into the lines then it needs to be what is called bench bleed. An internet search will describe the process.

The brake lines are disconnected and the fluid from the master cylinder fluid outlet holes is routed back into the reservoir (or dumped). The pedal is worked up and down until all the air is out of the master cylinder internal parts. if this process is not done first the master cylinder may never be able to pump fluid into the lines.

Try bench bleeding the master cylinder first. Once done connect the lines and bleed the lines. Bleed the longest line first, then the next longest, etc.

Once done determine if the pedal has firm pressure and can hold pressure.

If the lines are bleed and all other things working and the pedal still goes to the floor the master cylinder can be bad. I think there is some kind of check valve that goes bad or a seal. These days few repair master cylinders assuming one can find a rebuild kit. Typically one buys a new or rebuilt unit.

If fluid is still disappearing and there are not leaks at the slave cylinders, calipers, lines, hoses, etc then would look for brake fluid inside the power brake booster. If you suspect this remove the large diameter vacuum hose going to the booster from the intake manifold and check for signs of brake fluid being sucked into the hose.
 

Last edited by toyomoho; 01-28-2012 at 08:08 PM.
  #5  
Old 01-29-2012, 11:46 AM
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1. do not give car to anyone
2. if you broke rule one, then take it like a man and fix it without regret
3. is car garaged? if yes, pave floor with cardboard and let it sit overnight. it'll show itself
4. lines are metal tubing. toyo is right, they are not easy to punch. bend, yes, but not punch.
5. fitments sometimes go bad and leak. as in transitions between brake line and rubber hsoe to caliper.
6. are you replacing master? if so, bench bleed. bench bleeding kit sold everywhere and costs few bucks.
7. if you are not replacing master (why not? points towards it) - you can bench bleed on the car, with same kit, OR SIMPLY BLEED ENTIRE SYSTEM. the usual way. otherwise, you will have - to use kit - disconnect all brake lines, and taunting task is it.
8. why can't you simply remove caliper and fix bolt on bench? it's ten minute job.
9. you have ABS. module needs to be bled also. fortunately, you have older style ABS, that allows simple bleeding. I am blessed with new one, that will cost me pretty penny to bleed later, as it can be done with Toyota scanner only. anyhow, when done bleeding and - hopefully - got you pedal back, drive her out - into safe area - accelerate, and slam on brakes with both feet; repeat several times. this purges ABS module.
10. if yoy re-bled, and no pedal - no leaks, your master is gone bah-bye. btw, master rebuild kits cost pennies and it's very easy DIY job. got to have bench, vise, and basic tools though.

here's a bunch of vids for you:

camry master cylinder rebuild - YouTube
 
  #6  
Old 01-30-2012, 10:43 AM
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Thanks toyomoho and ukrkoz!

I'll bleed the master cylinder (the brake fluid reservoir was totally empty so it probably took in air).
In the meantime, I'm working on repairing all the bleeder valve screws, which I couldn't manage to thread out. Both rear tires are done (drum brakes) and I'm going to start the front tires (disk brakes, I think) today.
Then, to the master cylinder.
As far as bleeding the system goes, I need to bleed the master cylinder, all the brake lines (starting at the longest and working through to the shortest) and the ABS module, correct?

I appreciate the info, good sirs!

-Mike
 
  #7  
Old 01-30-2012, 11:57 AM
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Maybe, maybe not.

Start by bleeding the master cylinder. You will get nowhere if the master cylinder has air in it.

When bleeding have an assistant to operate the brake pedal.

For the master cylinder:

Suggest you wear protective gloves to keep the brake fluid off you hands and place a container under/around what will now be open line ports in the master cylinder to keep the brake fluid off the car. Brake fluid will take off paint, keep it off paint or wash it off when lots of water.

Fill the reservoir with clean fluid.

Disconnect the brake lines from master cylinder.

Have the assistant fully depress and HOLD the brake pedal. Note the fluid may spray out of the now open ports, use something to direct it into a container.

Using your fingers block off all the open ports on the master cylinder to keep air from coming in when the pedal is released.

Have the assistant release the pedal.

Repeat this process 3 to 4 times until you are certain there is no more air in the master cylinder. Don't allow the master cylinder reservoir to run out of fluid.

Once done reconnect the lines. Suggest now washing everything down with water to get any brake fluid off the car. Take care to localize the water as you don't want it getting into any wiring harness plugs, distributor cap or other items. A gentle wash, don't spray the water on any electrical items.

Start bleeding the brake lines beginning with the longest one typically the rear brake opposite the side of car the master cylinder is on.

Obtain a short section of clear plastic hose (most hardware stores carry this). Get a size that snugly fits the bleeder nipple and a length long enough to be routed into a clear plastic container.

Connect the hose to the nipple. If using a box wrench to open the nipple put the wrench on first the push on the hose. Place the other end in the container having enough brake fluid in it to the bottom of the hose. This will allow air bubbles coming out of the hose to more easily seen.

Bleed the line until only fluid comes out using the same procedure as the master cylinder except of course use the bleeder valve. Make sure the master cylinder reservoir never runs low on fluid. Suggest given there must now be air inside the brake line at the master cylinder end to bleed the fluid until all the old dark fluid comes out and is replaced by fresh fluid. This will indicate the new fluid you filling with is is now getting to the end of the line being bleed. Plus you will purge all the old brake fluid out which is a good for brake system life.

Once all the air is bleed out of this line, move to the next longest line which would be the one on the opposite rear side.

The move to the front opposite the master brake cylinder and finally the front drivers side.

The bleeder screw torque is 74 in-lbs (no need to over tighten).

The manual provides no method to bleed the ABS system as such the above procedure may be all you need.
 

Last edited by toyomoho; 01-30-2012 at 12:01 PM.
  #8  
Old 01-30-2012, 08:17 PM
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it's all dandy, but he can get far, simply bleeding through master cylinder. done that. it is advised to bleed master first, but it is quite doable on the car also.
you just need to keep adding fluid. it slowly but steadily goes in.
if no helper available, you can buy self bleeding kit, and do bleeding single handily, it's just pain, as bottle that comes with it is very small. I've used it before, it's OK in a pinch, and one can rig larger bottle into it.
you go pass rear, driver rear, pass front, driver front. your longest task will be pass rear, as it will take all the air out of master through and out. and couple of master refills. brake fluid is cheap though.
you most welcome to do bench bleeding but, like I said - beware what you asking for. removing brake lines and reinstalling them back is DAUNTING task. I have set of pipe wrenches for that, and every time I end up using vise grips, and end up having those little barbs busted. hate them.
 
  #9  
Old 01-31-2012, 05:55 PM
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Hello again! Well, I bench bled the master cylinder. Not too bad a job. I dismantled it and everything seemed to be in great shape. I re-installed it and then bled the brake lines at each wheel.
There was good pressure initially but the brake pedal soon became kind of spongy again. Not completely without pressure, just a little too spongy for my liking. I took it out for a little drive and the brakes worked well (aside from feeling too spongy).
I suspected a leak somewhere so I placed some cardboard under the car to see if I could spot brake fluid the next time I'm out (the Camry is about ten miles away at the family farm).
I'll be out there again tomorrow.
 
  #10  
Old 01-31-2012, 10:36 PM
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OK. spongy it is. my wife's Lexus has spongy pedal but brakes well.
DID YOU BLEED abs module?
 

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