A friend brought me this car with the issue that the brake pedal sinks to the floor when braking. She said it was never low on fluid and I couldn’t find any leaks so I replaced the master cylinder and bled all of the lines with a friend pumping the pedal. The pedal would still sink to the floor. I tried vacuum bleeding the brakes and found that the front left consistently had large bubbles. I Teflon taped the fitting on the caliper and the bleed screw which improved the problem but didn’t fix it. I then replaced the caliper. The front left caliper still won’t bleed and the brake pedal still goes to the floor. When I bleed it the regular way, the fluid comes out of the bleeder like it bled nicely but when vacuum bleeding, there are bubbles. Neither of the rubber hoses that connect to the caliper have any visible damage and there are still no leaks. I had a friend pump the brakes while looking at the hoses and their is no bulge or swelling in them. Could the ABS need to be bled?
Any ideas?
Thanks in advance.
The ABS system may require a completely different bleeding and troubleshooting procedure than you are using… It may not be an “air in the brakes” problem at all. Instead of spending money on parts you do not need, spend a few bucks on a service manual for the car. Be sure it includes the ABS …
You could have a collapsed inner liner of the flex line at the caliper. I’d change the flex line even though there’s no external evidence of damage.
I also have to ask if you bench bled the MC before installing it. Since the problem existed before you changed it, I won’t suggest that it’s the root cause of the problem, but it could be complicating it.
Are the bubbles large or small? Small bubbles mean the vacuum system is pulling air in through the bleeder threads. Large bubbles mean there’s still air in the lines, which is quite possible if you didn’t bench bleed the MC before installing it - - I never bench bleed them either because I seem to be incapable of doing so without making an unholy mess, but that means I accept that I’m gonna be bleeding for a much longer time with it on the car.
Also, @Caddyman makes a good point - be sure to check the service manual’s instructions for dealing with the ABS system. Some cars require special bleeding steps when they have ABS.
I bench bled the master cylinder and it bled well. I know it is a bad idea to clamp brake lines but in an effort to diagnose this problem, I clamped the two front brake lines right before the brake caliper. With the car running, I had a very firm pedal. If I remove either of the front clamps, even the one to the right front which has a caliper that bleeds fine, I lose all brake pressure. I take this to mean that the problem has to be between the middle of the brake hose and the caliper. Since the left front caliper is new, I’m thinking maybe the crimp fitting on the brake hose is bad. Does this sound possible?
Shadowfax (sick name by the way), I’ve seen bubbles that get past bleeder threads and they are larger than that although to be sure, I will Teflon the bleeder and see if that makes a difference.
I’ll see if I can track down the Toyota procedure for changing the master as well but if you have any more suggestions, please keep them coming.
You need a scanner to bleed the brake actuator to get a firm brake pedal.
Once the scanner is hooked up to the DLC3 connector under the dash, the scanner will provide instructions on the brake bleeding procedure.
Tester
You need a scanner to bleed the brake actuator to get a firm brake pedal.
Even though I get a firm pedal when clamping the lines?
CLAMPING THE LINES??? As in crushing the flex-hoses with a pair of vice-grips??
Jeff
You may not like what I have to say . . .
I have had far better luck using a diaphragm brake bleeder and the proper adapter, versus the way you did it
I happen to own a 2005 Camry and I used my own diaphragm brake bleeder and the appropriate adapter. I had absolutely no problems.
I must say I did it as preventive maintenance, not as part of a repair.
I’ve also replaced plenty of brake masters at work, bled them using the diaphragm brake bleeder, and more often than not, did not hook up my scan tool.
I also admit I’m biased . . . I’m no fan of vacuum brake bleeders. Quite the opposite, in fact
I’m just stating what Toyota states.
“If a firm brake pedal cannot be achieved after bleeding the brakes in the normal manner, the brake actuator must be bled and then each caliper per the instructions from the scanner.”
Tester
This includes info and a short video on a diaphragm-type pressure brake bleeder:
Even AutoZone has instructions on using the scanner/hand held tester to properly bleed the brakes.
Tester
You have isolated the problem to be at the calipers. Inspect both calipers to be sure the bleeder screws are at the top of the caliper. If they sold you a right side caliper to be installed on the left the caliper will be upside-down.
Lift the front of the car and check for play in the wheel bearings. With a very loose/failed wheel bearing the weight of the vehicle will tilt the brake rotor in pushing the caliper piston in. In this case when you apply the brake the caliper will jack the rotor back into position. A failed wheel bearing would seem to be obvious but I have seen people struggle with this.
FWIW, I have replaced master cylinder cup seals and bleed the master cylinders on dozens of RX330’s (similar braking system) for a recall and never had a complication or needed the scan tool.
I’m not familiar w/bleeding when you have ABS, but I’ve heard there can be complications and often a scan tool has to be used to open the various ABS ports at the right time.
But if you didn’t have ABS, I’d advise you like the others above say, to not try to bleed with the vacuum-bleed method. It is nearly impossible to avoid getting air into the system that way. I get good results on both my Corolla and Ford truck by having an assistant gently press down on the brake pedal (just with their hand, not their foot) while I work the bleeder screw. In this sequence: open bleeder, gently press down on brake pedal and hold at wood block stop, close bleeder, gently let up on brake pedal. I put a piece of wood under the brake pedal first to limit the motion to about 2/3 of what is possible. I don’t want the MC piston to move too far down the cylinder and damage the seal. Sometimes I don’t have an assistant and I hold the brake pedal down with a piece of wood while I crawl underneath to close the bleeder. Takes longer, but works just as well. Note: There is an order the wheels you bleed, I assume you are already aware of this.
If this is an older car – say 12 years or older – then if the above procedure didn’t work and the ABS wasn’t the cause and there was no signs of fluid leaking anywhere I’d be suspicious of all the flexible lines – they can look ok but still be bad – and that you got some bad luck and the replacement MC was also defective.
Shadowfax, you were right, I Teflon taped the bleeder on the caliper and am no longer pulling bubbles through. There is solid fluid coming out of all four calipers. So I guess a scan tool is required to do this. I kind of doubt it, but is there anywhere I can rent it from?
Also Tester, I assume that’s out of the manual? If you found it online, can you post the link? I would just like to check it out.
Thanks a lot guys.
Sorry! I can’t post a link because I get my information from here.
But what it say’s on the AutoZone site is what Toyota recommends.
I’m surprised I even found it on the AutoZone site.
Tester
Nevada, I agree the problem must be isolated to the calipers. But they both bleed perfectly now. Also the calipers are the right ones. Both bleeders are at the top. It now seems that a brake system with no air in it is not working.
So I guess my theory is that with the clamps on the lines (yes, bad idea, I don’t want to hear about it), there is a stiff pedal but there is also nothing moving (i.e. no brake pistons moving) and the MC must be good because no fluid is getting past that seal. Without the clamps, both front pistons can move so if there was any air, even just a little, anywhere in the system, the effect that air would have would be greatly multiplied. Therefore I think the right course of action to take would be to try this scan tool and if that doesn’t work, replace the hoses at the calipers. Then if that doesn’t work, replace the car because this was a cruel, cruel trick by Toyota.
Does this sound reasonable to anybody?
Again, I really appreciate the help. I’m not saying I’m the best mechanic but I’m sick of people with absolutely zero car experience telling me what might be wrong.
I’m still suspect of the flex lines. If the inner lining is detached, when the pedal is released and the MC piston retracts, the pressure drop in the line will pull the liner in rather than pull fluid from the reservoir, and when the pedal is again pushed, the pressure will expand the inner liner, increasing travel in the pedal. The inner liner will expand and contract with changes in the line pressure, effectively increasing the volume that needs to be displaced to push the caliper pistons.
I just really don’t want to spend the 70 bucks on the flex lines and have it be the wrong part. Especially since it’s not my money I’m spending. I suppose it wouldn’t be a bad idea since the car has 130,000 miles on it. Do you think I could see the condition of the inner liner if I take off the hose and shine a flash light down there?
Observe each brake caliper as someone applies and releases the brake, watch for movement. There should be very little movement, perhaps .010". If you see a caliper or piston moving more than that, this may be what is causing a full stroke of the brake peddle.