anyone ever mess up a brake booster by changing brake pads?
This was my 1st brake job i've ever done. I replaced my rotors and pads. Didn't open the bleeder valve and compressed the caliper piston while making sure the master cylinder didn't over flow, I did have to remove some brake fluid.
I started my truck up and press the brakes and it's feeling mushy. So I check for leaks and bleed my brakes. No Leaks and bleeding the brakes didn't help. I did notice a hissing sound near my brake pedal, I think I messed up my brake booster which was just replaced a couple of years ago. Could compressing the calipers without opening the bleeder valve mess up my brake booster? not sure what I did wrong. |
You need to set the pads to the rotor by pressing/pump the brake pedal until it's firm. It's normal as you previously pushed the pads & pistons all the way out in the previous step.
Don't open any bleeder valves at this point. Typically there is no need to touch the bleeders unless you are flushing the system |
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I agree...what year ? At firt I was going to say that I never heard of messing up a booster putting in break pads then boomerbob asked what year....made me think...those crazy brakes on 2001 and 2002 who knows maybe you could mess up a booster...on those years |
It’s a 2000 SR5.
I tried pumping the brakes, first with the truck on then with the truck off. Unfortunately no luck. Still getting a hissing sound from the back of the brake booster when I press and hold the brake with the truck is on. |
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I didn't remove the master cylinder cover when I compressed the caliper on first side (driver side). Could that have messed something up? |
I don’t know about master cylinders or boosters, but you can definitely mess up your abs sensors by not opening the bleeder while compressing the caliper pistons.
Sent from my iPhone using Tapatalk |
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Just to clarify, the pedal only starts to drop when you start the vehicle correct? Also, what brand and material are your replacement brake pads? Did you have the rotors resurfaced? I'm guessing you didn't, so are there uneven spots/gouges in the rotor? Did you burnish the pads to the rotor? Quote:
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I always thought this dude knew his stuff... what he says makes sense to me but that doesn’t mean our 4Runners are the same as an F150 YouTube Sent from my iPhone using Tapatalk |
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Edit: 1) The hottest part of your brake system is the rotor/pads not the caliper. 2) Unless you are racing your car in some form, towing more than you should be, or have a seized caliper your brake fluid won't come close to boiling. 3) The brake system is a sealed system so there's no way for gunk/debris/whatever to enter the brake fluid through the caliper. Most caliper's on vehicles still in use today are aluminum so there's no way for it to rust either. 4) You should be flushing your brake fluid every 5 years because brake fluid is hygroscopic (it attracts water which can get in through moisture in the air that the master cylinder cap vent allows in/out as necessary) and water in your brake fluid will decrease your brake performance. 5) I'm a mechanic at a GM dealership. I've worked at several and have never seen anyone crack the bleeders when compressing the caliper piston. I'm ASE certified in brakes as well. |
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Now here's a question for you. Just how far back did you compress? Did it go past the lip? I used a used pad to compress to limit it to just the edges no further. Don't even have to open booster fill. Something else went wrong in your case. Hope that helps. Luck and enjoy that Runner. :cowboy: |
Is it possible he simply has an air leak in his brake booster? If so it would be inside the booster and not visible most likely.
https://s14-eu5.startpage.com/cgi-bi...ticache=747472https://s14-eu5.startpage.com/cgi-bi...ticache=430565 |
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1. Fluid recevoir in caliper hold fluid that doesn't circulate 2. It gets hot (not boiling) and is constantly heat cycling. 3. Risk is to ABS Hydraulic Control Unit (not wheel sensors) if you manage to push the "contaminated" brake fluid up into that system 4. Opening the bleeder expels this fluid instead of pushing it up back into the brake lines 5. Using a brake bleeder further allows you to remove the fluid in the caliper reservoir replacing it with clean fluid from the master cylinder... short of performing a full flush. Do what you want, I'll continue to take this extra preventative step on my vehicles. Sorry OP for hyjacking your thread! Hope you find out what's up without too much $$ and trouble |
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