# Brake pedal "collapses" **URL:** \ **Category:** General Discussion\ **Created:** [August 6, 2023, 10:31am UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121 "2023-08-06T10:31:47Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![JunkOwner](https://avatars.discourse-cdn.com/v4/letter/j/f14d63/32.png) [@JunkOwner](https://community.cartalk.com/u/JunkOwner)\ **Post date:** [August 6, 2023, 10:31am UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/1 "2023-08-06T10:31:47Z")
After installing a rebuilt caliper and new pads on the front of a 01 Buick LeSabre, I cannot get a solid brake pedal. It will feel like it is building a steady resistance; as soon as the car is started, it collapses - righ to the floor. It is possible that there is still air in the line; I have only seen fluid come out of the bleeder on the new caliper. It seems like there should have been a big push of air right at first. We have bled all 4 calipers and read lots of online advice. Time to consult the “exeprts” at Car Talk Community: what say ye? ---
**Author:** ![TheWonderful90s](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/thewonderful90s/32/29584_2.png) [@TheWonderful90s](https://community.cartalk.com/u/TheWonderful90s)\ **Post date:** [August 6, 2023, 1:05pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/2 "2023-08-06T13:05:12Z")
Maybe it’s the master cylinder. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [August 6, 2023, 1:07pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/3 "2023-08-06T13:07:49Z")
1st question, is the bleeder above the brake hose on the caliper(s)?? lol (you never know) It sounds like air is trapped but it is also that you damaged the seals in the master cylinder after pumping the brakes, pushing the pedal all the way to the floor (could have damaged a seal from contaminated/dirty fluid)… You can clamp off all 4 brake hoses and test the pedal, if it is hard and doesn’t move then you can unclamp one hose at a time and see which unclamped hose allows the pedal to drop a lot (more then about 1/2")… If the pedal does not drop with all 4 clamps on and then drops really low only on one wheel then that wheel is where your issue is… If the pedal drops even with the hoses clamped off then your issue is in the master cylinder or maybe even the abs system… Clamping the hoses is a simple way to tell you if your issue is above or below the brake hoses… ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [August 6, 2023, 1:18pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/4 "2023-08-06T13:18:12Z")
> [@davesmopar](#): > > 1st question, is the bleeder above the brake hose on the caliper(s)?? lol (you never know) I did that once. Luckily it didn’t take me long to figure it out. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [August 6, 2023, 1:46pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/5 "2023-08-06T13:46:20Z")
I learned from others mistakes on that one… lol I did laugh at my business partner when we had a shop together years ago after I watched him install front calipers on the wrong sides, I asked him multiple times if he did it correctly and he kept saying YES that he went by the part number sequence with the lower number being the left side which in a lot of brake part cases is backwards from what you would think… lol I finally told him after my legs got tired from pumping and laughing… it was a slow day and I get bored easy sometimes… don’t worry he has done worse to me… 🤣 ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [August 6, 2023, 4:13pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/6 "2023-08-06T16:13:28Z")
Maybe the old master cylinder couldn’t take all the commotion. ---
**Author:** ![weekend-warrior](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/weekend-warrior/32/26122_2.png) [@weekend-warrior](https://community.cartalk.com/u/weekend-warrior)\ **Post date:** [August 6, 2023, 5:55pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/7 "2023-08-06T17:55:40Z")
> [@JunkOwner](#): > > I have only seen fluid come out of the bleeder on the new caliper. You should see fluid come out of every caliper. I would try bleeding again. start with right rear, then left rear, right front and then left front. check to make sure you do not have a leak anywhere. if there are no leaks found, and you are getting brake fluid out of all four corners with no air, then I would say it is the master cylinder that is bad. ---
**Author:** ![keith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/keith/32/5518_2.png) [@keith](https://community.cartalk.com/u/keith)\ **Post date:** [August 6, 2023, 7:24pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/8 "2023-08-06T19:24:06Z")
Is the caliper that you bought the one for that side? I bought a caliper set once and it had two passenger side calipers, no drivers side. Had to take it back. You can tell if it is the wrong one because the bleed screw will be lower than the hose connection. In order to get all the air out, the bleed screw has to be at the highest point in the calipers cylinder. Brake fluid in at the bottom, air out at the top. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [August 6, 2023, 11:02pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/9 "2023-08-06T23:02:07Z")
Ask a helper to watch the brake booster/MC when you step on the brake pedal with & without engine running. Might provide a clue. Are you needing to add brake fluid to keep brake reservoir full? Does your car use ABS? If so, are you following the manufacturer’s ABS bleed procedures? My guess, something is amiss with newly installed caliper. Suggest to disassemble the brake parts on that wheel for further inspection. ---
**Author:** ![JunkOwner](https://avatars.discourse-cdn.com/v4/letter/j/f14d63/32.png) [@JunkOwner](https://community.cartalk.com/u/JunkOwner)\ **Post date:** [August 7, 2023, 3:47am UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/10 "2023-08-07T03:47:16Z")
Thank you all for these valuable suggestions! Eliminating some possibilities: I finally figured out what hose above the bleeder refers to. Perfect sense that the air rises. Yes, the hose connection is higher and we have the correct caliper. A point of clarification - I had not seen air bubbles escape from the new caliper. All 4 calipers are expelling brake fluid. I clalmped the line to the new caliper and got a very solid pedal which collapsed the moment the engine was started.I fear those suggestions of the master cylinder may be correct or the booster. Thanks again. ---
**Author:** ![JunkOwner](https://avatars.discourse-cdn.com/v4/letter/j/f14d63/32.png) [@JunkOwner](https://community.cartalk.com/u/JunkOwner)\ **Post date:** [August 7, 2023, 3:48am UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/11 "2023-08-07T03:48:24Z")
Sounds like you guys were good friends who had fun working together. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [August 7, 2023, 12:11pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/12 "2023-08-07T12:11:10Z")
> [@JunkOwner](#): > > Yes, the hose connection is higher The bleeder screw HAS to be above the hose, NOT the hose above the bleeder screw… I hope you mistyped that… > [@JunkOwner](#): > > I clalmped the line to the new caliper Has to be **ALL 4 caliper hoses clamped off** and only one released at a time… ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [August 7, 2023, 12:20pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/13 "2023-08-07T12:20:33Z")
> [@JunkOwner](#): > > Sounds like you guys were good friends who had fun working together. Yeah we used to prank each other all the time, trying to out scare the other… 🤣 The best part was we never had a vehicle issue between the 2 of us we couldn’t figure out… We were known for problem solving way back then (late 90’s)… ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [August 7, 2023, 12:26pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/14 "2023-08-07T12:26:17Z")
> [@George\_San\_Jose1](#): > > Does your car use ABS? A 2001 Buick LeSabre has ABS ---
**Author:** ![JunkOwner](https://avatars.discourse-cdn.com/v4/letter/j/f14d63/32.png) [@JunkOwner](https://community.cartalk.com/u/JunkOwner)\ **Post date:** [August 7, 2023, 1:19pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/15 "2023-08-07T13:19:57Z")
I can see the pads flex against the rotor. Nothing remarkable up by the MC / booster. ---
**Author:** ![JunkOwner](https://avatars.discourse-cdn.com/v4/letter/j/f14d63/32.png) [@JunkOwner](https://community.cartalk.com/u/JunkOwner)\ **Post date:** [August 7, 2023, 1:21pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/16 "2023-08-07T13:21:26Z")
I didnt describe that well. When the caliper was first installed and we tried to bleed it, all that I saw come out of the bleeder was fluid, no air bubbles. Other calipers expel brake fluid only - no air. ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [August 7, 2023, 1:21pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/17 "2023-08-07T13:21:57Z")
> [@davesmopar](#): > > The best part was we never had a vehicle issue between the 2 of us we couldn’t figure out… > We were known for problem solving way back then (late 90’s)… Problem solving is what being a mechanic is all about. Anyone can be taught to replace parts. It’s the diagnosis that really makes one a mechanic. ---
**Author:** ![JunkOwner](https://avatars.discourse-cdn.com/v4/letter/j/f14d63/32.png) [@JunkOwner](https://community.cartalk.com/u/JunkOwner)\ **Post date:** [August 7, 2023, 1:22pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/18 "2023-08-07T13:22:44Z")
Afraid of that. This car isn’t worth the parts we’ve already put on it. It is my son’s old heap with many issues. Ready for the scrap pile. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [August 7, 2023, 2:36pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/19 "2023-08-07T14:36:44Z")
We towed vehicles from 5 major repair centers cause they couldn’t find/fix the issue, we could/did… But we also built engines, transmissions and rear ends (performance and stock), and worked on simple vehicles up to Medium Duty trucks (TopKick, bucket truck, rear-engine motorhomes etc size)… Our downfall was we should have specialized in something (one or two things) instead of working on anything and everything that fit in front of the building… lol ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [August 7, 2023, 2:41pm UTC](https://community.cartalk.com/t/brake-pedal-collapses/192121/20 "2023-08-07T14:41:54Z")
> [@JunkOwner](#): > > When the caliper was first installed and we tried to bleed it, all that I saw come out of the bleeder was fluid, no air bubbles. That sounds like the caliper bleeder screw is below the brake hose (bottom of caliper piston), therefor only pushing out fluid as all the air is trapped at the top, whereas the bleeder screw needs to be… [Next page](https://community.cartalk.com/t/brake-pedal-collapses/192121.md?page=2)