Strange brake issue - hard pedal

R

Renton4runner

New member
I started having some issues with my brakes recently and am hoping someone on the forum can send me in the right direction.

What happens is that when I am driving, my brake pedal will feel stiff when I am trying to brake, and my braking power seems noticeably diminished. If l start pumping the brake, the pedal gets harder and the braking power seems to diminish with each additional brake pump until they are hard as a rock and don't seem to brake at all. The problem seems like it's worse when it's really cold, but that could be my imagination.

I took it in to a shop on Thursday and they thought it was the power brake booster, so they swapped out the booster and the master cylinder. When I went to pick it up, they kept stalling and delaying the pick up time and eventually gave it back to me saying that it still felt weird to them, but I could take it home for the weekend and see how it felt to me. Well, to me it feels exactly the same as when I first brought it in...

So what could be causing this problem?
The shop said they bled the brakes multiple times and put in new fluids. I think they said they checked the wheel bearings too. Rotors and calipers were replaced like a year in a half ago. Drums were serviced then too. As far as shops go, this place is pretty honest and I don't think they intentionally misled me, but I am certainly annoyed that we just replaced a bunch of stuff that didn't seem to fix the issue.

Hopefully someone has an idea of what else it could be.

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If the new booster (is it OEM) isn't bad make sure the vacuum line from the manifold to the booster is good.

If it is fine then take a look at the condition of the calipers.
 
Seems to kick in when I start to slide without any issue. I hear that nice pleasant sound... Is there anything else I should be doing to check the abs?

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There is an ABS diagnostic port on the driver's side of the intake manifold in order to check for codes. I have never done the check myself and can't off the top of my head remember the procedure. If you can hear it working I don't know if that is your problem.

If you can find access to an online factory service manual then it can show you how to check for codes.
 
LittleCaesar said:
There is an ABS diagnostic port on the driver's side of the intake manifold in order to check for codes. I have never done the check myself and can't off the top of my head remember the procedure. If you can hear it working I don't know if that is your problem.

If you can find access to an online factory service manual then it can show you how to check for codes.
Click to expand...

If he doesn't have an ABS light, he doesn't have any codes.
 
This issue seemed to come up after I went off roading in some deep snow(2+ feet), but that could just be a coincidence.

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Tested it some more today. Breaks feel generally weak when I start the car in the morning, but felt a bit better after about 20 minutes. They symptom of losing my breaks entirely after pumping them 5 or 6 times is always there though. After the 5th or 6th pump the break pedal is hard as a rock and doesn't seem to provide any breaking power.

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Renton4runner said:
Tested it some more today. Breaks feel generally weak when I start the car in the morning, but felt a bit better after about 20 minutes. They symptom of losing my breaks entirely after pumping them 5 or 6 times is always there though. After the 5th or 6th pump the break pedal is hard as a rock and doesn't seem to provide any breaking power.

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Click to expand...

Is this not normal? Every vehicle I've ever driven loses brake power when you're stepping on them that many times.
 
It sounds like you have insufficient vacuum and it can't keep up with repetitive brake pumps. I'd hook up a vacuum gauge on the line to the booster and I'd also be suspicious about the check valve.
 
OldManKamps said:
Is this not normal? Every vehicle I've ever driven loses brake power when you're stepping on them that many times.
Click to expand...
Well, let me take a step back.

My issue is that my brakes seem to randomly have this issue where the pedal gets hard and I lose braking power. I have been trying to find a repeatable way to make it reoccur so I can take it to a shop and show them what causes it to happen. If I take it to shop and say"well, it's not acting up now but it sometimes does" then they don't have much to go on. So far the ways I've seen it trigger are:
1. When I first start it up in the morning. Braking power seems substantially diminished and pedal feels hard and doesn't seem to go down all the way.
2. Driving through deep snow for hours caused the same issue. I am therefore assuming it has something to do with being cold as I wasn't using my breaks in the snow.
3. Pumping the pedal while driving. My understanding was that pumping your brakes shouldn't cause you to lose all breaking power after a few pumps. Maybe I am wrong, but that is what I thought.

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What you're describing most commonly points to the brake check valve, but as you said that it has already be replaced then I wouldn't know. How fresh is your fluid? Flushed anytime recently?

Check out all of your vacuum lines, flush your fluid, and look back into that brake check valve.
 
Renton4runner said:
Well, let me take a step back.

My issue is that my brakes seem to randomly have this issue where the pedal gets hard and I lose braking power. I have been trying to find a repeatable way to make it reoccur so I can take it to a shop and show them what causes it to happen. If I take it to shop and say"well, it's not acting up now but it sometimes does" then they don't have much to go on. So far the ways I've seen it trigger are:
1. When I first start it up in the morning. Braking power seems substantially diminished and pedal feels hard and doesn't seem to go down all the way.
2. Driving through deep snow for hours caused the same issue. I am therefore assuming it has something to do with being cold as I wasn't using my breaks in the snow.
3. Pumping the pedal while driving. My understanding was that pumping your brakes shouldn't cause you to lose all breaking power after a few pumps. Maybe I am wrong, but that is what I thought.

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Click to expand...
Rats I'm not sure man!
 
wake_rider said:
What you're describing most commonly points to the brake check valve, but as you said that it has already be replaced then I wouldn't know. How fresh is your fluid? Flushed anytime recently?

Check out all of your vacuum lines, flush your fluid, and look back into that brake check valve.
Click to expand...
Yah, new check valve and they flushed and replaced the fluids 3 times.

It seems like the only other possible explanation is checking all of the vacuum lines?


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