Check out The Accord Project videos! Link to Part 1: ua-cam.com/video/Q5FUVJTCDnY/v-deo.html Link to Part 2: ua-cam.com/video/LXgKbk6HABA/v-deo.html Link to Part 3: ua-cam.com/video/oT3QwC5GKh8/v-deo.html Link to Part 4: ua-cam.com/video/vmV4NRvHYX0/v-deo.html Link to Part 5: ua-cam.com/video/JTOwrZ1cxt4/v-deo.html Link to Part 6: ua-cam.com/video/vDWx73DG3gY/v-deo.html Link to Part 7: ua-cam.com/video/zKyk30TkKng/v-deo.html Link to Part 8: ua-cam.com/video/x_q4a-DjDZo/v-deo.html Link to Part 9: ua-cam.com/video/x-TA0U8sY4o/v-deo.html
Brilliant! Greetings from rainy England. I was stuck trying to fix my brakes on an Audi A6, which would work fine but occasionally suddenly fail. This was not improving marital harmony. I watched your video, where you explain how the servo assist system works and how to test for faults. Armed with this knowledge, I strode manfully to the carpark, where I had abandoned the dangerous car. Problem solved! - the vacuum feed pipe was not tight in the rubber tube that goes through the bulkhead to the brake servo. I wrapped ptfe tape round the serrated pipe end to make a tight seal and added a tie wrap round the rubber pipe to stop it coming off. The brakes work much better now. It was knowing how it worked that enabled me to diagnose and then to fix the fault: thanks for sharing the knowledge.
I had recently replaced a fitting that fixed a vacuum issue (fitting on manifold) that had turned on check engine light. Parts store clerk said it was for brakes and whether I was having issues. We weren't, but the check engine light was on for vacuum issue. Light went away when fitting was replaced, but came back on several days later (I did not reset light, it just turned off when fitting replaced). Diagnostic showed no errors, but history showed brake issue. It's clear now. Video helped explain how vacuum loss could cause the "brake" check engine light issue. Thanks.
Great job on explaining simply and covering everything, the shops hate you but we DIY people are very grateful! I'm sure you've helped atleast 100k of the 5 million that watched this if not more! God bless brother 😇
Very informative! My fluid level was down below minimum but after topping it off the light remained on. The dealership recommended tapping the reservoir to free the measuring arm in the reservoir. IT WORKED!! LIGHT OFF!!
Thanks for the video! Releasing the clips meant my wife had to assist to pull the switch out while I pushed the keeper clips in. Nothing like fumblefarting my way through it. 😂 2009 Chevy Avalanche. Key positions; all the way counterclockwise = Lock, 1st = Acc, 2nd = Run, 3rd (spring loaded) = Start. This truck does not turn counterclockwise for Accessory. Thanks again!
I have bled my brakes 3 times for squishy pedal syndrome. The third time I bled my brakes I used a pressure bleeder and my brakes were great and fine for a couple months until today when the squishy pedal came back. I didn't think it was the master cylinder because it would get better and not come back after bleeding the brakes. Each time it would come back, it would seemingly happen over night. I did the last test that you described to do that tests your master cylinder, with the engine off. I pumped a bunch of times(6 or 7) to get rid of vacuum in the brake booster, then I held the brake for 15 seconds. My brake pedal held firm and didn't sink, it did do a really weird thing though after 15 seconds of having this very very slow pulsing that would push my foot back very very slightly almost not noticeable. It would push back for maybe 5 seconds in a gradient pulse, and then go back that same amount. Again, my engine was off, and the distance it pushed back was so so so small so I would think it wouldn't be an issue, but I also never expected it to have a gradually sweeping pulse pushing my foot back when the engine was off. I would think it is air in my system, or a leak? What do you think? If anyone else has any ideas or experience with this, I would really appreciate any expertise! Really wanting my brake gremlins to be stomped out after maybe 4-5 months of this now.
Fabtastic video, I'm trying to diagnose a problem with a 2002 Volvo 2.4 T XC70. The brake pedal is really spongey, when turning on the car it pretty much hits the floor with very little pressure. The garage I've relied on have changed the master cylinder and are now suggesting its the booster (but it's a subframe dropped job, 4 hours labour) so I'm wanting to diagnose it myself before going any further.
2012 tahoe 5.3 the check valve is built-in the sensor, and failed the test (I could inhale and exhale freely). Replaced the sensor and the "Service brakes soon" message is gone. Thanks!!
Just picked up a 2003 F150, will definitely be using these methods to see what is going on. Upon the first press of the brake pedal, the pedal goes down quite far, then if you pump the brakes the resistance goes up, and the pedal does not have to be depressed as far. So it is as if you have to build up the pressure. The pedal is very easy to press, so I am suspecting the master cylinder. It feels as if the booster is doing its job.
Thank you, following your instructions I determined the issue was the master cylinder. Replaced the master cylinder on my 2010 acura rdx and it no longer sinks.
Great video honestly and the only one that I've seen that explains all the symptoms that a brake booster can exhibit or a master cylinder. I was having a problem yesterday as a matter of fact and I pressed on the brake and it was traveling too far and it felt like it took a lot longer to brake. I did some of these checks but one of them I did not know about and that was the very last one in your video where you could have an internal leak in your master cylinder. So I tried it and my pedal did sink down further. I checked all the brake lines and saw no brake fluid coming out whatsoever so I'm automatically assuming it's a faulty or failing master cylinder. I bought my master cylinder from O'Reilly's and it has a warranty so I'm going to change it out today or swap it out for another one and then bleed the system starting with the master cylinder bleed. I hope this helps my breaking issue as on these 96 Chevy Silverado c1500s or k1500s they've always had some sort of a spongy pedal even from factory brand new but not what I'm exhibiting. I had changed the master cylinder two years ago and it's worked fine ever since until yesterday I'm also thinking about jacking up the truck and taking the slider pins out and checking those for movement and relubricating them and putting them back in. I changed the brakes from semi-metallic to ceramic about a year ago and it breaks fine it just has a lot of pedal travel and takes a lot longer to stop so I'm thinking there may be a warped seal or a slightly torn seal that is going to get worse if I don't get it fixed inside the master cylinder. Wish me luck
Update; I changed my master cylinder bled it and was able to get the bleeder screws loose on the front tires but both back tires on my truck the nuts on the bleeder screws are rounded off. Go freaking figure. When I get them off I'm putting self bleeders on there. My truck actually breaks really well though even though the front has been bled but the back still has air in it. I'm driving it very carefully and only using it to get to work and back and breaking way ahead of time until I get paid Wednesday. I get off at 12:00 p.m. and I can work on getting those bleeder screws out and replacing them so I can bleed the whole system properly
I Replaced brake booster, master cylinder, calipers and brake hoses. My brake pedal sinks hard. As if nothing there. So check for a vacuum leak. Got it. On my 89' sububran.
I am impressed by your football acheivements. Congratulations. You were a part of an amazing team and you are an amazing man to help people with your education. Thank you for this awesomely articulated video. Your shared education on this matter is a big help to me. I hope more people that make videos share their sports acheivements at the beginning like you did. Go Laney!
The brake pedal is not airy when the vehicle is at rest but super spongy when it's running. Despite almost sinking all the way to the bottom, it actually works super well and the grip sets in just right in the middle. It seems to me that this does not match with the description of this video. I wonder if it is the master cylinder issue, or something else, but what can that be?
I'm a very mechanical guy but I'm stumped on this one. I have a 2008 Escalade. Brakes were perfect, I put on all new rotors, calipers and pads about a year ago and brakes have been super smooth and worked perfectly. But last week I had to really stand on the brake pedal to keep from hitting a car that pulled out in front of me. I wasn't going fast, maybe 10 MPH or less. But since then the brakes want to stay engaged under certain conditions. If I come to a complete stop, the brakes release fine. But if I lightly press the brakes like to slow for a turn or to go over a speed hump the brakes lock. They don't "lock" as I can't move the truck, but when I remove my foot the truck continues to slow down and will come to a stop on it's own. A quick firm press on the pedal and it releases but driving is a pain. The pedal seems to not be retracting all the way up in these conditions. I can put my foot under the pedal and pull up to release it. And of course when trying to drive the truck with the brakes lightly engaged I get all the ABS, traction control warning lights. Any thoughts?
Wow, to the point and very professional, I was able to check some things while actually watching this video…great content I will be following you from now on!!!
1991 Mazda pickup, B2200, the booster checks good. But I have brake fluid leaking through the booster shaft on to the drivers floor matt, definitely a Brake Master Cyl. problem. Good Video. You can talk to me all day or give me a manual, and I won't learn a thing, show me a UA-cam Video, and that's when I learn. I'm a "show me" shade tree mechanic. Thanks You for a great video.
if i slam on my brakes, the pedal wont go down, and wont brake. but if i press the brake slowly, it brakes normally. what could it be? done your steps, seemed fine.
I am having an issue with my Honda Civic 2004 ES On smooth surface my brakes work perfectly, but as soon as I hit an uneven surface while braking, the brake's pedal gets harder, starts blocking and shaking. I am still wondering what is the issue with that. Can I get an advice about the issue please?
Thank you for the tips. I did all the test and my truck passed. I bleed all the breaks and when it's running I still have the pedal going to the floor and very little stopping power. Anybody know what else it can be?
My truck has the same problem. The adviser said the break lines had leaked so the air filled the lines, I checked and bled the fluid but it didn't do any good, so I am going to replace the master cylinder since the other video said a bad master cylinder could cause a sinking pedal. Good luck with your truck problem.
I got same truck with manual . My booster pass all tests check valve ok but for some reason booster vacuum will deplete after 10 minutes. Why the slow leak and will it get worse ? My long term fuel trim is 8% a little lean but i think that is a fuel injector spray issue. Could it be gasket between master cyl and booster ? By the way this guy knows what he is talking about excellent troubleshooter.
My brakes become stiff by themselves with the engine not running. At the garage they said it was normal. I told them it was normal if you press the brakes 2-3 times, but not by it self. Anyway they said the important is that it works while running, and they never saw this problem ever. Do you know what the problem can be?
My problem with my 1988 Jeep YJ is that I hear air leaking from around the brake pedal, but I stops when I press on the brake pedal, and starts again when I release the brake pedal?
Sorry to bother you, but I have 1970 lincoln mark iii when the car is off, the brake pedal is very hard. But when I turn the car on the pedal go all the way down.??? Any idea what can be!!
Thanks to your great video I was able to realize that the defect of my toyota tacoma is that the vacuum brake booster does not work well and I replaced it and fixed it. Thanks you very much for sharing your knowledge and experience. Thanks sss👍👍👍👍👍
My good sir through you I have found a bad booster and master cylinder at the same time... Sometimes lean codes sometimes evap codes and even transmission and fuel issues... These cars with all these sensors it's like a chicken with no head
This is really good. My pedal only gets hard randomly so I take it the check valve is probably sticking? Some days no problems other days I go to start the car and it's hard.
Hi what would it be if I hear a hissing noise (air escaping) coming down from where the brake pedal is. Would it be the brake booster or master cylinder? Thanks
First of all, Niiice hair! .... I ran into an unusual situation. Brake booster on a Jaguar x-type pretty much tested bad while sitting at rest test (after shutting off engine). One decent brake feel the next one almost hard as a rock and the third one rock solid, essentially not holding vacuum for enough braking. The check valve tested ok, brake pedal dipped when starting engine, so all ok until the test for the vacuum being held after engine shutoff. Lastly, the brakes themselves were dragging severely. So, I removed the Master cylinder and adjusted the push rod length. (the moment I took off the master, I could tell the brake pressure released) I had to do it twice, but worked like a charm the second time around. There's an acorn nut at the end of the pushrod (I had a helper step on the brake to extend the pushrod) I then used a needle nose vise grip to keep the pushrod (just behind the acorn nut) from turning and turned the nut in at least 6 turns in my case. The wheels spun freely and the car ran flawless. The car was struggling to shift as well, the ABS light had come on too. But it all re-set to normal after my stint. Like I said way unusual, and a first for me on this adjustment.
What about a bad grommet around the check valve? My car is 17 years old, and maybe the seals are bad. Would soapy water be able to detect bad grommets and tubes on the outside? I have a low mileage lexus with 50k miles that has rock hard pedal during cold start only. All other times brakes operate normally.
Question: Can a faulty brake booster cause the engine or car to shake when in drive and the brake is applied? I tested the vehicle while it was lifted off the ground, and when I put it in drive, it shook noticeably, which I suspect is due to a vacuum leak. I just want to confirm before replacing the brake booster, as I've already fixed/replaced many parts on this vehicle and don't have the means to take it to a shop or get a new one.
Thanx for the vid ..... I just used your quick trouble shooting to check my booster on my Acura legend.....which is bad since pedal action is hard and stiff to stop..........my question is what makes boosters go bad....mainly the diaphragm inside blowing out??
My brake pedal is rock solid (no movement) when I press it in the morning (cold). As soon as the engine starts the pedal moves and brakes works fine. The brake pedal continues to work normally all day even parked outside my office for 8hrs. However, after parking overnight in the morning it’s rock hard again. Vacuum hose & return valve replaced. Does this indicate a slow leak in the brake booster. Other symptom is throttle surging 2-3,000rpm under light load.
I have similar symptoms on my nissan murano 2012 -hard break when cold and then when engine start it would go down but yesterday the engine not started and I towed to mechanic and he will do it monday and we went there as we were going down and described situation he said it might be alternator. Did you found the cause of the problem on your car?
What if there is a significant leak from booster and back of master cylinder already replaced the master cylinder .I have not checked the check valve ok big dog any info would be great.
So a bad brake booster makes it harder to press the pedal? My brakes are spongey and I replaced the master cylinder and bled the brakes and they’re still spongey I have no clue what else it could be. I put all new pads and rotors on them as well
I have an issue with my i20 2013 sports petrol. The brake travel is too much and there is not enough pressure in the pedal. But when car engine is off and I pump the brakes a couple times and then turn the engine on the brake travel is reduced and braking is also improved. Could you tell me what could be the starting point for this investigation?
What about a soft pedal on the first pedal push but as you pumped a second time, the pedal offers more resistance and more breaking power? All with engine running. Then drive a bit and the same scenario happens.
What if the brakes seem to work conpletely fine. But you have to go almost to the floor for the brake pads to actually make contact with the rotors. Or shoes to drums? Ive checked the pads and rotors. There is plenty of material left.
@@RickaramaTrama-lc1ys but i when to year auto care and midas auto care and they both did not know what was the problem .Midas told me the anti- lock abs whats good.
Could a bad brake booster be causing both my calipers to drag on my 99 f150? Replaced master cylinder and calipers still an intermittent issue im battling. Thanks
Dave, Excellent video. I have few questions may be helpful to other viewers. May be my questions are silly but will help a lot to understand and correlate lot others 1) At 4.45 you said Air is escaping, but I think it is vacuum because if vacuum is not there in booster it push the pedal up. 2) At 5.00 you said, for good brake booster we should be able to push and hold the pedal for first 30 seconds, so why is that it wont hold after 30 seconds, does that mean after 30 seconds vacuum will disappear if so how will it deplete, again this question is for good brake booster not for bad. I am trying to understand why it can hold only for 30 seconds and how is vacuum depleted. I dont think vaccum in booster will go past check valve so my theory is it should hold all the time, unless there is a depletion somewhere. 3) AT 6:07 the failed one in this case is pushed farther than it is supposed to be, what I didn't understand is failed one is hard to press, but in this test it goes farther i didn't understand the theory. 4) at 8.33, you said we need to have 3 brake assist without vacuum. I assume you are using existing vacuum in booster, is that right. because without vacum we may not get that 3 brake assist.. Sorry too many questions.
1. Yes it is losing the air that is under vacuum. 2. The 30 seconds is just a general guideline that can be used as a test, these system are not designed to be 100% air tight over long periods 3. It is not pushed farther down, it is pushed down to normal position. The pedal started up higher (and traveled further) because there was no vacuum stored in the booster to assist at the start, but as soon as engine turned on then vacuum started to assist and the pedal went down to normal position. This booster was bad but it was able to hold enough vacuum to assist as long as the engine was on (but it made the truck run severely lean, as shown in my P0171 video). 4. Yes the booster should be able to hold enough vacuum inside to assist for 3 presses of the brake pedal.
I'm working on a 73 elcamino thinking i have a bad brake booster. When driving ill come to a stop and the engine idle drops real low, then when coming off the brake to the gas the engine stalls. It restarts back up at a good idle as if nothing happend. Thinking that the booster is pulling pressure from the engine
Hi I did your last test, no leak brake padel didn’t go down yet my mechanic says master cylinder is bad because my padel goes down when engine idling and when car is off and parked. Why you think padel sink? Thanks
Can a failing brake booster causes engine misfire..im in a situation where the engine misfires when not accelerating and ive got no breaks in that situ..however when i accelerate the breaks come back
HI, I have a Mazda 5 2010. The breaks works fine in general driving with 2000 or more rmp.but with slow drving in town etc rmp around 1000 the breakpadle get 'hard' after pushing 1 or 2 times. I have changed the vacumehose pack with the valve included... What can be the course ? Hope you can reply me..😊🇳🇴
Usually a bad master cylinder or leak in the brake lines/calipers. Had this happen to me going downhill in my 74 Mercedes, brakes went from holding pressure, straight to the floor, I blew a brake line hahaha
I have a 2005 Dosge grand Caravan I’m trying to get road ready for one of my daughters. It sat without being used for 2 years. The brake pedal seems to be pulled towards the floor. I can pull the brake up with my foot with light pressure, but if I let it go, it sinks back down and the brakes engage (even the brake lights come on). I was thinking bad booster, but if I heard you correctly, it could also be a bad check valve? I haven’t heard the problem I’m having described exactly so I’m not sure. When the pedal sinks down, the brakes engage very well.
Check out The Accord Project videos!
Link to Part 1: ua-cam.com/video/Q5FUVJTCDnY/v-deo.html
Link to Part 2: ua-cam.com/video/LXgKbk6HABA/v-deo.html
Link to Part 3: ua-cam.com/video/oT3QwC5GKh8/v-deo.html
Link to Part 4: ua-cam.com/video/vmV4NRvHYX0/v-deo.html
Link to Part 5: ua-cam.com/video/JTOwrZ1cxt4/v-deo.html
Link to Part 6: ua-cam.com/video/vDWx73DG3gY/v-deo.html
Link to Part 7: ua-cam.com/video/zKyk30TkKng/v-deo.html
Link to Part 8: ua-cam.com/video/x_q4a-DjDZo/v-deo.html
Link to Part 9: ua-cam.com/video/x-TA0U8sY4o/v-deo.html
Brilliant! Greetings from rainy England. I was stuck trying to fix my brakes on an Audi A6, which would work fine but occasionally suddenly fail. This was not improving marital harmony. I watched your video, where you explain how the servo assist system works and how to test for faults. Armed with this knowledge, I strode manfully to the carpark, where I had abandoned the dangerous car. Problem solved! - the vacuum feed pipe was not tight in the rubber tube that goes through the bulkhead to the brake servo. I wrapped ptfe tape round the serrated pipe end to make a tight seal and added a tie wrap round the rubber pipe to stop it coming off. The brakes work much better now. It was knowing how it worked that enabled me to diagnose and then to fix the fault: thanks for sharing the knowledge.
Thank you for sharing this information with us 🇺🇸
6:07 mine is firm with the car off, turn the car on drops almost all the way to the firewall
You for making this video. Trying to self diagnose after I was given a questionable diagnosis
Thank you
WOW!! Learned more about brakes in this 10 minute video than in the last ten years! You are the brake GOAT!
MANY THANKS!!
I had recently replaced a fitting that fixed a vacuum issue (fitting on manifold) that had turned on check engine light. Parts store clerk said it was for brakes and whether I was having issues. We weren't, but the check engine light was on for vacuum issue. Light went away when fitting was replaced, but came back on several days later (I did not reset light, it just turned off when fitting replaced). Diagnostic showed no errors, but history showed brake issue. It's clear now. Video helped explain how vacuum loss could cause the "brake" check engine light issue. Thanks.
👍
I know this is an old video but I just want to say dude you just help me out a lot this video will help people for years to come
Glad it helped, thanks for the comment!
It just helped me.
Been driving myself crazy trying to figure out why my van only runs right when the booster vacuum hose is disconnected.
It explains EVERY aspect of testing the brake booster. Thank you,
Thanks 👍!
I love the way you explained everything. You did this better than most other sites on UA-cam. THANK YOU!
I appreciate the comment, thanks!
Just helped me diagnose a the problem. Saved me from buying parts I didn’t need and some frustration. Many thanks!
Glad it helped, thanks for the comment!
I am an A.S.E. tech and this is an excellent video for b-booster
fault trouble shooting.
I appreciate the comment, thanks!
Lol ASE I had that phoney stuff 30 years ago 😂
ASE tech LMAO
I think everybody else has already said it: you do a fantastic job explaining the how and why of each simple test. Thank you!
Thanks 👍!
Great job on explaining simply and covering everything, the shops hate you but we DIY people are very grateful! I'm sure you've helped atleast 100k of the 5 million that watched this if not more! God bless brother 😇
I'm wondering if you have any deaf people in your family. The way you communicate through you hands is phenomenal. Thank you.
BY FAR, the best video on the subject that I have found. Sincere thanks!
Serge in Chicago.
Imma go see!
10/10 mate. Straight to the point, great, simple, yet vital information other channels aren't addressing.
I appreciate the comment, thank you!
I have to pass a knowledge exam soon to change class as a mechanic and your video are very helpful, you are a great teacher.
I appreciate the comment, thanks!
Hi
Very informative! My fluid level was down below minimum but after topping it off the light remained on. The dealership recommended tapping the reservoir to free the measuring arm in the reservoir. IT WORKED!! LIGHT OFF!!
👍
Thanks for the video! Releasing the clips meant my wife had to assist to pull the switch out while I pushed the keeper clips in. Nothing like fumblefarting my way through it. 😂 2009 Chevy Avalanche. Key positions; all the way counterclockwise = Lock, 1st = Acc, 2nd = Run, 3rd (spring loaded) = Start. This truck does not turn counterclockwise for Accessory. Thanks again!
I have bled my brakes 3 times for squishy pedal syndrome. The third time I bled my brakes I used a pressure bleeder and my brakes were great and fine for a couple months until today when the squishy pedal came back. I didn't think it was the master cylinder because it would get better and not come back after bleeding the brakes. Each time it would come back, it would seemingly happen over night.
I did the last test that you described to do that tests your master cylinder, with the engine off. I pumped a bunch of times(6 or 7) to get rid of vacuum in the brake booster, then I held the brake for 15 seconds. My brake pedal held firm and didn't sink, it did do a really weird thing though after 15 seconds of having this very very slow pulsing that would push my foot back very very slightly almost not noticeable. It would push back for maybe 5 seconds in a gradient pulse, and then go back that same amount. Again, my engine was off, and the distance it pushed back was so so so small so I would think it wouldn't be an issue, but I also never expected it to have a gradually sweeping pulse pushing my foot back when the engine was off.
I would think it is air in my system, or a leak? What do you think? If anyone else has any ideas or experience with this, I would really appreciate any expertise! Really wanting my brake gremlins to be stomped out after maybe 4-5 months of this now.
Did you figure it out?
Thanks!
I appreciate the support, thank you!!
can you just remove the check valve, or woul the pressure be to high and cause problems ?
Thank you so much for making this video. Your time and detail is saving people thousands of $.
Very well explained. Appreciate the accurate information! I Wish school teachers knew/explained their curriculum this well.
Thank you, I appreciate the comment!
They do! That's why our kids are becoming commies
@@capitanvonchickenpants8492 I see what ya did there lol. agree. also doesnt help they encourage little boys to think they're girls.
@@darkskinwhite look up yuri Bezmenov
Thanks Big Dog! Very detailed yet easy to understand, excellent job!
Fabtastic video, I'm trying to diagnose a problem with a 2002 Volvo 2.4 T XC70. The brake pedal is really spongey, when turning on the car it pretty much hits the floor with very little pressure. The garage I've relied on have changed the master cylinder and are now suggesting its the booster (but it's a subframe dropped job, 4 hours labour) so I'm wanting to diagnose it myself before going any further.
2012 tahoe 5.3 the check valve is built-in the sensor, and failed the test (I could inhale and exhale freely). Replaced the sensor and the "Service brakes soon" message is gone. Thanks!!
Just picked up a 2003 F150, will definitely be using these methods to see what is going on. Upon the first press of the brake pedal, the pedal goes down quite far, then if you pump the brakes the resistance goes up, and the pedal does not have to be depressed as far. So it is as if you have to build up the pressure. The pedal is very easy to press, so I am suspecting the master cylinder. It feels as if the booster is doing its job.
Thank you, following your instructions I determined the issue was the master cylinder. Replaced the master cylinder on my 2010 acura rdx and it no longer sinks.
What if it's leaking air between booster and master cylinder, what would be that problem, thank you
This helped me out and saved me from a $300 repair job. Thank you!
Glad it helped, thanks for the comment!
Great video honestly and the only one that I've seen that explains all the symptoms that a brake booster can exhibit or a master cylinder. I was having a problem yesterday as a matter of fact and I pressed on the brake and it was traveling too far and it felt like it took a lot longer to brake. I did some of these checks but one of them I did not know about and that was the very last one in your video where you could have an internal leak in your master cylinder. So I tried it and my pedal did sink down further. I checked all the brake lines and saw no brake fluid coming out whatsoever so I'm automatically assuming it's a faulty or failing master cylinder. I bought my master cylinder from O'Reilly's and it has a warranty so I'm going to change it out today or swap it out for another one and then bleed the system starting with the master cylinder bleed. I hope this helps my breaking issue as on these 96 Chevy Silverado c1500s or k1500s they've always had some sort of a spongy pedal even from factory brand new but not what I'm exhibiting. I had changed the master cylinder two years ago and it's worked fine ever since until yesterday I'm also thinking about jacking up the truck and taking the slider pins out and checking those for movement and relubricating them and putting them back in. I changed the brakes from semi-metallic to ceramic about a year ago and it breaks fine it just has a lot of pedal travel and takes a lot longer to stop so I'm thinking there may be a warped seal or a slightly torn seal that is going to get worse if I don't get it fixed inside the master cylinder. Wish me luck
Update; I changed my master cylinder bled it and was able to get the bleeder screws loose on the front tires but both back tires on my truck the nuts on the bleeder screws are rounded off. Go freaking figure. When I get them off I'm putting self bleeders on there. My truck actually breaks really well though even though the front has been bled but the back still has air in it. I'm driving it very carefully and only using it to get to work and back and breaking way ahead of time until I get paid Wednesday. I get off at 12:00 p.m. and I can work on getting those bleeder screws out and replacing them so I can bleed the whole system properly
What if the brakes don't push back when the car is turned off. When it turn the car on, there is a dull clicking sound coming from behind the dash.
I Replaced brake booster, master cylinder, calipers and brake hoses. My brake pedal sinks hard. As if nothing there. So check for a vacuum leak. Got it. On my 89' sububran.
yes this help it was master cylinder and now i learned how to appreciate a power booster
I am impressed by your football acheivements. Congratulations. You were a part of an amazing team and you are an amazing man to help people with your education. Thank you for this awesomely articulated video. Your shared education on this matter is a big help to me. I hope more people that make videos share their sports acheivements at the beginning like you did. Go Laney!
The brake pedal is not airy when the vehicle is at rest but super spongy when it's running. Despite almost sinking all the way to the bottom, it actually works super well and the grip sets in just right in the middle. It seems to me that this does not match with the description of this video. I wonder if it is the master cylinder issue, or something else, but what can that be?
I'm a very mechanical guy but I'm stumped on this one. I have a 2008 Escalade. Brakes were perfect, I put on all new rotors, calipers and pads about a year ago and brakes have been super smooth and worked perfectly. But last week I had to really stand on the brake pedal to keep from hitting a car that pulled out in front of me. I wasn't going fast, maybe 10 MPH or less. But since then the brakes want to stay engaged under certain conditions. If I come to a complete stop, the brakes release fine. But if I lightly press the brakes like to slow for a turn or to go over a speed hump the brakes lock. They don't "lock" as I can't move the truck, but when I remove my foot the truck continues to slow down and will come to a stop on it's own. A quick firm press on the pedal and it releases but driving is a pain. The pedal seems to not be retracting all the way up in these conditions. I can put my foot under the pedal and pull up to release it. And of course when trying to drive the truck with the brakes lightly engaged I get all the ABS, traction control warning lights. Any thoughts?
Very good video found a leak between hose and valve. It should not leak air when move the hose left to right slowly.
Thanks for the comment!
Wow, to the point and very professional, I was able to check some things while actually watching this video…great content I will be following you from now on!!!
Thanks and welcome!
1991 Mazda pickup, B2200, the booster checks good. But I have brake fluid leaking through the booster shaft on to the drivers floor matt, definitely a Brake Master Cyl. problem. Good Video. You can talk to me all day or give me a manual, and I won't learn a thing, show me a UA-cam Video, and that's when I learn. I'm a "show me" shade tree mechanic. Thanks You for a great video.
Glad it helped, thanks for the comment!
Thank you! Not sure what I liked more...the tutorial or the detailed explanation! I'm on my way to properly diagnosed my brake booster!
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if i slam on my brakes, the pedal wont go down, and wont brake. but if i press the brake slowly, it brakes normally. what could it be? done your steps, seemed fine.
Also if STFT continues to climb while applying pressure to brake pedal. The booster has a vacuum leak.
great info. thanks. Since a week now, i am getting a hissing (pssssst) sound new brake paddle while applying brakes. What could it be.
Would a bad brake booster cause the vehicle to jump 500 RPMs when the brake is applied or does that sound more like a vacuum failure?
I am having an issue with my Honda Civic 2004 ES
On smooth surface my brakes work perfectly, but as soon as I hit an uneven surface while braking, the brake's pedal gets harder, starts blocking and shaking. I am still wondering what is the issue with that. Can I get an advice about the issue please?
Don't get me wrong, but the way you move your hands is great!
Thanks for the questions. Could you tell me if you heard any air noise when you press the pedal ? Thanks
Thank you for the tips. I did all the test and my truck passed. I bleed all the breaks and when it's running I still have the pedal going to the floor and very little stopping power. Anybody know what else it can be?
My truck has the same problem. The adviser said the break lines had leaked so the air filled the lines, I checked and bled the fluid but it didn't do any good, so I am going to replace the master cylinder since the other video said a bad master cylinder could cause a sinking pedal. Good luck with your truck problem.
I got same truck with manual . My booster pass all tests check valve ok but for some reason booster vacuum will deplete after 10 minutes.
Why the slow leak and will it get worse ? My long term fuel trim is 8% a little lean but i think that is a fuel injector spray issue.
Could it be gasket between master cyl and booster ? By the way this guy knows what he is talking about excellent troubleshooter.
My brakes become stiff by themselves with the engine not running. At the garage they said it was normal. I told them it was normal if you press the brakes 2-3 times, but not by it self. Anyway they said the important is that it works while running, and they never saw this problem ever. Do you know what the problem can be?
What about air leaking in between the master cylinder? What would cause this? Improper installation of the master cylinder?
My problem with my 1988 Jeep YJ is that I hear air leaking from around the brake pedal, but I stops when I press on the brake pedal, and starts again when I release the brake pedal?
Mine was just professionally replaced now it whines any ideas?
Sorry to bother you, but I have 1970 lincoln mark iii when the car is off, the brake pedal is very hard. But when I turn the car on the pedal go all the way down.???
Any idea what can be!!
Great I wish you can do video for the cylinder
What about when your turning over and you have to continually press the break peddle to get the car started
Is another indication hearing air when your pushing on the brakes when in motion?
Thanks to your great video I was able to realize that the defect of my toyota tacoma is that the vacuum brake booster does not work well and I replaced it and fixed it. Thanks you very much for sharing your knowledge and experience. Thanks sss👍👍👍👍👍
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My good sir through you I have found a bad booster and master cylinder at the same time... Sometimes lean codes sometimes evap codes and even transmission and fuel issues... These cars with all these sensors it's like a chicken with no head
what about if you press the brake pedal and the pedal doesnt return back up? I also notice the pedal goes back up when the car is off?
how did you know when the master cylinder failure or the booster?
8:53 the last test he explains what would indicate a leak in the master cylinder internal seals
Also the break booster will cause a lean condition on your fuel trims.... On both bank's...
This is really good. My pedal only gets hard randomly so I take it the check valve is probably sticking? Some days no problems other days I go to start the car and it's hard.
That is a possibility, thanks for the comment!
What can cause the pedal to sink a bit when the AC compressor cycles on? I am thinking vacuum lose?
Hi what would it be if I hear a hissing noise (air escaping) coming down from where the brake pedal is. Would it be the brake booster or master cylinder? Thanks
Booster if it hisses when u press on it
Great video, there is another way to tes it with scanner reading the short term data stream.
First of all, Niiice hair! ....
I ran into an unusual situation. Brake booster on a Jaguar x-type pretty much tested bad while sitting at rest test (after shutting off engine). One decent brake feel the next one almost hard as a rock and the third one rock solid, essentially not holding vacuum for enough braking. The check valve tested ok, brake pedal dipped when starting engine, so all ok until the test for the vacuum being held after engine shutoff. Lastly, the brakes themselves were dragging severely.
So, I removed the Master cylinder and adjusted the push rod length. (the moment I took off the master, I could tell the brake pressure released) I had to do it twice, but worked like a charm the second time around. There's an acorn nut at the end of the pushrod (I had a helper step on the brake to extend the pushrod) I then used a needle nose vise grip to keep the pushrod (just behind the acorn nut) from turning and turned the nut in at least 6 turns in my case. The wheels spun freely and the car ran flawless. The car was struggling to shift as well, the ABS light had come on too. But it all re-set to normal after my stint. Like I said way unusual, and a first for me on this adjustment.
lol! (on the hair) 😀
What if the brake pedal stays down after pressing? And I need to lift it back up? Don’t want to replace something I don’t need too ?
So 98 Mazda b2500 brakes work fine. Then I shut truck off then pedal sinks enough to turn brake lights on I have to pull pedal up to shut them off.
Once I changed my booster on my 02 escalade, how do I got the pressure back to the peddle?
What about a bad grommet around the check valve? My car is 17 years old, and maybe the seals are bad. Would soapy water be able to detect bad grommets and tubes on the outside?
I have a low mileage lexus with 50k miles that has rock hard pedal during cold start only. All other times brakes operate normally.
Question: Can a faulty brake booster cause the engine or car to shake when in drive and the brake is applied? I tested the vehicle while it was lifted off the ground, and when I put it in drive, it shook noticeably, which I suspect is due to a vacuum leak. I just want to confirm before replacing the brake booster, as I've already fixed/replaced many parts on this vehicle and don't have the means to take it to a shop or get a new one.
Will a bad brake booster cause the brakes to be spongy while driving? I check the lines the master cylinder I see no leaks.
Thanx for the vid ..... I just used your quick trouble shooting to check my booster on my Acura legend.....which is bad since pedal action is hard and stiff to stop..........my question is what makes boosters go bad....mainly the diaphragm inside blowing out??
Yes many times the diaphragm goes bad.
My brake pedal is rock solid (no movement) when I press it in the morning (cold). As soon as the engine starts the pedal moves and brakes works fine. The brake pedal continues to work normally all day even parked outside my office for 8hrs. However, after parking overnight in the morning it’s rock hard again. Vacuum hose & return valve replaced. Does this indicate a slow leak in the brake booster. Other symptom is throttle surging 2-3,000rpm under light load.
I have similar symptoms on my nissan murano 2012 -hard break when cold and then when engine start it would go down but yesterday the engine not started and I towed to mechanic and he will do it monday and we went there as we were going down and described situation he said it might be alternator. Did you found the cause of the problem on your car?
Many times pumpin the pedal but no much longer the pressure is going can tell what part problem is that? Cylinder or cecum problem?
What if there is a significant leak from booster and back of master cylinder already replaced the master cylinder .I have not checked the check valve ok big dog any info would be great.
So a bad brake booster makes it harder to press the pedal? My brakes are spongey and I replaced the master cylinder and bled the brakes and they’re still spongey I have no clue what else it could be. I put all new pads and rotors on them as well
I have an issue with my i20 2013 sports petrol. The brake travel is too much and there is not enough pressure in the pedal. But when car engine is off and I pump the brakes a couple times and then turn the engine on the brake travel is reduced and braking is also improved. Could you tell me what could be the starting point for this investigation?
82 cutlass supreme v6,3.8 break pedal got hard when coming to a stop had to pump n final stop scare me ?
Couldn’t have done it better myself excellent video sir! Every possible easy way to check the booster/vacuum/master cylinder system. Thank you
How high is the vacuum? Can I hook it up to a hose and use it outside to do some moulding?
Thanks for the knowledge man.
I appreciate the comment, thank you!
What about a soft pedal on the first pedal push but as you pumped a second time, the pedal offers more resistance and more breaking power? All with engine running.
Then drive a bit and the same scenario happens.
08 scion tc. New master c. Press down 3 times and it’s normal (gets stiff) but when cars on pedal goes to floor..help!?
What if the brakes seem to work conpletely fine. But you have to go almost to the floor for the brake pads to actually make contact with the rotors. Or shoes to drums? Ive checked the pads and rotors. There is plenty of material left.
I wish if u do a video of how to know a failed "ABS ANTI LOCK brake pump modulator" mine is 03 acura mdx
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I have a E46 and the brake is really , Any advice on what may the problem
I have a cheveolet tahoe 2001 the car brakes by it self. I change the master cylinder but still brake by it self
I would check your anti-lock module by pulling the fuse for it and try brakes this way with it disconnected. This worked for me one time. Good luck!
@@RickaramaTrama-lc1ys but i when to year auto care and midas auto care and they both did not know what was the problem .Midas told me the anti- lock abs whats good.
Could a bad brake booster be causing both my calipers to drag on my 99 f150? Replaced master cylinder and calipers still an intermittent issue im battling. Thanks
Great guy very good teacher helped a lot Thank-you.
Dave, Excellent video. I have few questions may be helpful to other viewers. May be my questions are silly but will help a lot to understand and correlate lot others
1) At 4.45 you said Air is escaping, but I think it is vacuum because if vacuum is not there in booster it push the pedal up.
2) At 5.00 you said, for good brake booster we should be able to push and hold the pedal for first 30 seconds, so why is that it wont hold after 30 seconds, does that mean after 30 seconds vacuum will disappear if so how will it deplete, again this question is for good brake booster not for bad. I am trying to understand why it can hold only for 30 seconds and how is vacuum depleted. I dont think vaccum in booster will go past check valve so my theory is it should hold all the time, unless there is a depletion somewhere.
3) AT 6:07 the failed one in this case is pushed farther than it is supposed to be, what I didn't understand is failed one is hard to press, but in this test it goes farther i didn't understand the theory.
4) at 8.33, you said we need to have 3 brake assist without vacuum. I assume you are using existing vacuum in booster, is that right. because without vacum we may not get that 3 brake assist..
Sorry too many questions.
1. Yes it is losing the air that is under vacuum.
2. The 30 seconds is just a general guideline that can be used as a test, these system are not designed to be 100% air tight over long periods
3. It is not pushed farther down, it is pushed down to normal position. The pedal started up higher (and traveled further) because there was no vacuum stored in the booster to assist at the start, but as soon as engine turned on then vacuum started to assist and the pedal went down to normal position. This booster was bad but it was able to hold enough vacuum to assist as long as the engine was on (but it made the truck run severely lean, as shown in my P0171 video).
4. Yes the booster should be able to hold enough vacuum inside to assist for 3 presses of the brake pedal.
I'checked my car.the engine engine vacumm doest exist.is it one way valve?
I'm working on a 73 elcamino thinking i have a bad brake booster. When driving ill come to a stop and the engine idle drops real low, then when coming off the brake to the gas the engine stalls. It restarts back up at a good idle as if nothing happend. Thinking that the booster is pulling pressure from the engine
Hi
I did your last test, no leak brake padel didn’t go down yet my mechanic says master cylinder is bad because my padel goes down when engine idling and when car is off and parked. Why you think padel sink?
Thanks
Can a failing brake booster causes engine misfire..im in a situation where the engine misfires when not accelerating and ive got no breaks in that situ..however when i accelerate the breaks come back
Any idea if a cracked manifold would reduce vacuum?
If you have engine off pat the brakes and air gushes out does that mean its bad also?
so what if it goes down the pedal to the floor all the lines of blood is it the master or is it the booster
HI,
I have a Mazda 5 2010.
The breaks works fine in general driving with 2000 or more rmp.but with slow drving in town etc rmp around 1000 the breakpadle get 'hard' after pushing 1 or 2 times.
I have changed the vacumehose pack with the valve included...
What can be the course ?
Hope you can reply me..😊🇳🇴
What if your brake pedal sinks all the way down when it's turned on?
I would like to know the same thing, but I’m pretty sure it means you have a brake *fluid* leak or bad master cylinder
Usually a bad master cylinder or leak in the brake lines/calipers. Had this happen to me going downhill in my 74 Mercedes, brakes went from holding pressure, straight to the floor, I blew a brake line hahaha
Or the cylinders on drums are bad
@@MrMrsregor But why does it leak only when the vehicle gets started?
Yes, that was not explained in this video
I have a 2005 Dosge grand Caravan I’m trying to get road ready for one of my daughters. It sat without being used for 2 years. The brake pedal seems to be pulled towards the floor. I can pull the brake up with my foot with light pressure, but if I let it go, it sinks back down and the brakes engage (even the brake lights come on). I was thinking bad booster, but if I heard you correctly, it could also be a bad check valve? I haven’t heard the problem I’m having described exactly so I’m not sure. When the pedal sinks down, the brakes engage very well.