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Brake Pedal Problem

2005 Toyota Camry with ABS. Bleed brakes using pump method (car off). The pedal was tight and up high. Start car and pedal slowly goes to floor. Car still stops but barely and only grabs within 1/2 inch of full to floor. Tried bleeding with car on. Tried jumping on brakes about 10 times activating ABS then rebleed. Also put in new master cylinder which I manually bled. No leaks anywhere. Can’t figure this one out ?? I have bled brakes on alot of cars and never had this happen.

Bad new master cylinder most probable, second most probable non metal brake line hoses deteriorated.

How much of a brake job did you do before needing to bleed the brakes? Did you replace calipers? The reason I ask is one that dumbfounded a lot of guys was a brake job where someone inadvertentantly put the new left front caliper on the right and vice versa. That made the bleeders be on the bottom of the calipers. Since air always rises to the top, there was no air in the area of the bleeders. They bled 'em and bled 'em. All they got was fluid.

The master cylinder has to be mated to the power brake booster. The pushrod coming out the front of the booster that contacts the master cylinder is adjustable. It sounds like you have too much gap between the pushrod and the master cylinder.

Another thread just reminded me. Have you checked the rear brakes for correct adjustment? If the brakes are way out of adjustment, and require a lot of movement before the shoes contact the drum, that is a lot of pedal travel required before the brakes engage.

I have found that the one man brake bleeders work very nicely to get any trapped air out of the system. I too have completed many replacements of components and found these newer cars can be difficult to get all the air out. To me, it sounds like some air is still trapped somewhere in this car. The fact you can get a hard pedal when the key is off sounds like the pump rod from the booster is engaging properly and the master itself is able to build pressure and hold it.

Can you tell us why you needed to bleed the brakes in the first place? Were you chasing this problem from the start and hoping bleeding would fix it or had you replaced something and needed to bleed it?

If the pedal stays high and firm with the car off, then its not a master cylinder problem. This also makes it unlikely to be an issue with rear brake adjustment. If you pump the brakes with the car off the pedal goes from feeling soft to completely firm because it exhausts the vacuum reserve in the brake booster. Anytime you do that and start the car with your foot on the brake pedal you’ll feel the pedal sink as the engine replenishes the vacuum in the booster.

So it all sounds sort of normal, except, of course for the excessive pedal travel. So I’d be inclined to first go along with keith and say to check the MC/booster pushrod gap.

Some clarifications might also help. First, as asked, where did all of this start? As in, what got you bleeding the brakes to begin with. Second, with the car off pump the brake pedal a bunch of times to kill any remaining vacuum in the booster. Now wait a few minutes and pump the pedal a bunch more times. If it starts soft/low and firms up, then you are still probably looking at air in the system. When you said that you manually bled the MC, I assume that means you bench bled it? Its also possible that you have some badly deteriorated flexible brake lines that are ballooning out on you.

Thanks for the helpful comments

  1. brake calipers are right side up
  2. rear brakes have been adjusted
  3. pushrod adjustment - did not know about this adjustment - should I feel this when I bleed with the engine off - because the pedal is up tight and solid until I turn on the car
  4. in general I feel that there is air trapped somewhere and that the mc adjustment and mc are working correctly because I can build pressure - ABS bleeding??

I do not have access to the car except every other weekend (daughters). Will get back with update after next try.

Plan :

  1. will find out exactly what was done for the brakes to have to be bled
  2. will try the pump test suggested by cigroller
  3. I bench bled the new master cylinder then pumped out small amount of air after I mounted it as per instruction - seemed to bleed out the air as expected
  4. I will check the brake lines for balloning but the looked in good shape
  5. will check the master cylinder push rod adjustment

with car on but vacuum hose disconnected and plugged should the pedal stay up high but just harder to push? does the vacuum power assist give more force to compress any air in the system and thats why the pedal goes to floor?

  1. I think you are on track here since it does get firm but I am no expert on this adjustment. If it gives you a firm pedal near the top of travel, while the car is off, I would assume the push rod it adjusted correctly.

  2. Not sure how to bleed the ABS system completely. I would continue to try the system bleeding you probably have been doing.

If you disconnect the vacuum line and run the car the booster would/should act the same as it did with the engine off. I believe the booster increases the amount of pressure that can be applied to the master cylinder thus increasing the amount of clamp the calipers can apply. Along with that, air is more compressible than the fluid and is why you would feel a decrease in pedal travel when the motor is running.

I have been given new master cylinders that were bad also so don’t let new hamper your thoughts that it may still have a bad component.

The one man brake bleeders are about $5.00 at places like Harbor Freight or even Oreilly’s Auto parts. If you are doing this by yourself, put the bottle and hose for the one man bleeder above the calipers or slave cylinders. Crack the valve open and you should see fluid start to rise up the hose. If you keep that exit path raised air will try to escape around the fluid and you will see bubbles run up the hose. You can still get someone to pump the pedal, hold it and you crack the valve open while the one man bleeder is attached. The fluid will be captured that way and you will see if air escapes by watching in the clear hose. You may have to hold the hose on the bleeder valve because of the pedal pressure from the helper because it can push it off. Make sure to close off the valve good before the person inside the car raises their foot at all because air can be drawn in around the threads of the bleeder valve.

Someone is driving this car for two weeks before you make more attempts to properly bleed the brakes? That means either the brakes are working, or someone(s) is in danger. Suggest your daughter, or whoever is driving the car, take it to a shop (even a Toyota dealer) and get the brakes working properly.