Brake pedal popping noise

Hello everyone. I'm on here because I have no idea what that popping noise is. Every time I press the brake pedal it pops. It started after my mechanic replaced the brake master cylinder. And it hasn't stopped since then. Everything works fine but it's annoying as he'll. I have a video clip of it but the file is not supported on this forum. Please help.

 

Upload your clip to Youtube and post the link to the video here.

 

Www.imgur.com

Drag and drop the video into the page. Or upload using their tool. Then post a link here. No account required.

Meanwhile, mech probably used non-oem parts and stupid shit happens with non-oem parts, sadly the oem on MC and booster are $$$$. The mech probably noticed it also but “it works, technically” and so they shipped it.

Can you start the engine, pop the hood and put your hand on the MC and booster while someone else taps the pedal? See if anything obvious is happening? I’m going to assume the rod isn’t properly adjusted, which you won’t see but … visual and touch inspection may shed some light.

 

@artsr2002 so I have a Samsung s23 ultra and it looks like it doesn't allow the upload of my mp4 file.

 

@shifty` thank you so much for replying. You're famous on this forum. I'm working on uploading the file.

 

@shifty` @artsr2002 see if you guys can see the link since this forum didn't allow upload. Hopefully you guys can see the link.

https://youtube.com/shorts/d78krmRwykc?si=30s2gvqYzZwQXHw6

 

It works.

Weird question, but with the engine running, have you gotten your head up inder the dash with a flashlight pointing up there to watch as you press in the pedal?

To me it sounds like rigid rubber popping. Seems to happen mid-pedal too, which is weird also. I mean, again, I'd take it back to the mechanic since it's easily reproducable. Let his ass figure it out.

 

Finally it worked. Lol

@shifty` to answer your first question….. I have looked under the dash while I press the pedal and I can’t see anything. But I’ll check again I’m going out with it now and I’ll get back on here a little later. And I’ll try and put my phone under there also to see if I can post another video lol.

 

@shifty` This is behind the brake pedal.

https://youtu.be/LPVe3ut3vbw?si=5hLGvk363dYetM4s

 

@shifty` It looks like the popping is coming from the brake booster. What could have gone wrong?

https://youtube.com/shorts/ZrW1xmB31ZA?si=RWCzKyzWXJNLy40L

 

Sounds like the diaphragm in the booster is popping through/shot to me. Looks like your mechanic fucked up.

If so, that sucks. New OEM booster assembly for my truck is almost $1k. Boof.

This may help to visualize what I'm talking about:

https://www.youtube.com/watch?v=wbTUvp-tD5M​

 

Wow! Am I in trouble here? Do I have to change the booster right away? Is it dangerous?

 

Are the brakes working? Booster is only there to provide assistance, I'm coming up short on how this could possibly backfire on you.

Honestly, maybe I'm just being harsh (it's been a rough day) and it's just something stupid, like a failure on their part to adjust the pushrod accordingly. I dunno.

I'd bring it back to the shop. Make them aware it has been happening since you got the car, and you're upset you didn't get the car back in the same working order it was before they repaired it.

 

Well here is the situation; I brought the car back the very next day and I told him about the popping noise and he told me he would check it out. So I picked it up at the end of the day and when I did he told me in a very nice way that it works fine. It does work I told him but it was extremely annoying and I didn’t want to keep driving it that way.

He then replied in a way to make me understand that it’s an old car and things are going to keep breaking and some things you fix and some things you can milk.

But I’m the type of guy that I take care of my cars and even though I’m not financially able to fix everything cosmetically I do like to be on top of them mechanically. So I’ve exhausted myself with him and I don’t wanna lose the guy so I think I’m just going to buy the booster and see if he helps me out with the labor cost. I hope.

 

Yeah, sounds like it's maybe time to find a new mechanic. That's bullshit

Meanwhile, let's see if we can figure out wtf the issue is. I'm thinking late or early engagement of the booster may be resulting in the diaphragm 'popping' when you finally push through and vacuum releases, I'm thinking the following may help, but I may also tag one of our Toyo mechs (or ask for mods to move this to the 'ask a tech' forum) to see what they think.

Would you say the pedal feels stiffer than it was before the MC work? Or softer? Or about the same?

Check to make sure the vacuum going into the booster is attached properly. Confirm the check valve that vacuum line plugs into is properly seated. If it is, I'm curious ... what happens if you unplug the vacuum line and try using the brake with it unplugged (with engine running), do you still hear the pop? Reattach the vacuum line after checking.

I notice you don't get the pop every time. Does the velocity at which you press the pedal have any influence? Like if you rapidly mash the pedal, does the pop still happen at the same frequency? What if you lightly push down the pedal?

 

The pedal is a little stiffer than before the MC change. But not a lot, I mean the truck brakes are 10 times better than they were.

I will take a look at the vacuum line and test it out like you instructed.

So yes the pop only happens the first time in a series of pedal uses. But let’s say I’m getting to a stop, it pops, then it pops again in the next block. It’s always the initial press. It’s as if the pressure needs to build up every few seconds for it to pop.

Velocity in which I press doesn’t matter. It will still pop.
If I rapidly mash the pedal it only happens the first time.
And it still pops if I lightly push down on the pedal.

 

I've seen others have this problem in different vehicles, but haven't seen anyone on here have it. I've never personally experienced it on any of the array of vehicles I've owned, so I'm short on advice for how to proceed.

I'm sure it'll be tougher to brake once you pull the vacuum line, with engine running. The whole point for me is to remove vacuum source to see if absence of vacuum makes the pop go away, or makes the pop show up even more and/or every pedal press.

The fact it's happening mid-pedal-travel immediately made me think "Mech didn't adjust the pushrod to the right length!" OEM MCs, at least in my limited experience, typically come pre-set to the rod length range they need to be in. Aftermarket, not always the case, some rod length adjustment is required. Hell, there was a dude on here not long ago whose rod was dicked up, then he got the right length and realized the MC was bad as I recall.

Anyway, curious what the vacuum test does. I wouldn't doubt if there's a series of tests you can do in the FSM also. I'm less-familiar with your earlier year. I've dug into the FSM for my '06 a hell of a lot so far.

 

Wow @shifty` thank you so for your input, you’ve given so much insight on a problem which was otherwise lost. I’m so grateful.

Anyways now that that’s out of the way…..stay tuned for the results of the test.

 

Don't thank me yet, problem isn't solved. Just be happy when haven't broken anything so far.

 

Hey @shifty` sorry for the disappearance. Long story.

So yeah I disconnected the vacuum hose from the booster and it still pops.

 

Raising this topic back up to the top as I'm experiencing similar issues. New MC and booster, still popping when applying the brakes. Almost like the pedal snags for a second, pops, then drops the rest of the way down. Removing the vacuum hose gives me a rock hard deal that doesn't move. I'm at a loss here.

 

Get down under the dash and press the pedal with engine running so you can see if anything is catching.