[w0527102]

I could really use some advice here please. So I have a 2012 Chevy Impala LT FE2 suspension. I have replaced the following on both front axels: steering knuckles, lower ball joints, wheel hub assembly, wire harness from speed sensor to main loom, sway bar link bushings, inner & outer tie rods with new bellows, calipers, high performance rotors and brake pads. I blead the breaks multiple times and was thinking I was missing air because with the car off it builds a little pressure but then as soon as I start the car the brake pedal falls to floor when I press on it. So I was assuming that it was the diaphragm inside the break booster but once I took the master cylinder off I don't see the diaphragm like it's on like a 2011 model. Does anybody know anything about this if there's something else I'm not thinking about or is there a check valve that I can check. I went on the Chilton's website and ordered a book but they messed my payment up and I can't find a repair manual for anything. View attachment 165113 View attachment 165114 View attachment 165115 View attachment 165116
Here's some pictures after I've removed the master cylinder I think on like a 2011 there's a diaphragm in that empty space there on the brake booster I was thinking it was that that was leaking but I can kind of hear some air when I push the brake when I had it all before I took it apart and is there something I'm missing or does anyone have a repair manual for a 12 Impala LT? Thank you for any help you all can provide.

 

[w0527102]

You can go to your local library and use your there books. They have repair manuals that you can reference too. the library card is free. You can also access the manual from your home computer but you need the library account to access the website. good luck !

 

[gahsr]

Just a thought, you did put the new calipers on the correct sides?

 

[RickCoMatic]

Bench Bleed a brand new Master Cylinder.
Look right in your vast collection of absolutely useless Phillips or Cross Head drivers and grab a new recruit.
Hit the Grinder.
Here's our Bench Bleeding Tool.
Teflon™ Wrap Cap Screws.
Taped Cap Screws aid in plugging / venting new MC ports while priming the new MC.
New Brake Fluid.
Lots.

 

[Wesley Wideman]

Just a thought, you did put the new calipers on the correct sides?

Yeah I'm positive because I've had to turn in two different calipers for warranty replacement within a week and haven't even got the car on the road yet. I usually buy my parts online but I bought my calipers at O'Reilly's with lifetime warranty but the bleeder valves on them were horrible so the first one broke inside the caliper the next one was threaded like sideways so I was getting air leaking around it. That's the last time I'll buy calipers from O'Reilly's that's for sure.

 

[Wesley Wideman]

So just an update where I'm at on the Impala I was thinking I would have it on the road last week but the break thing was just driving me insane. I still am not totally sure why the issue I'm having is there to begin with because when I brought put the car into the garage the brakes were working at least they were stopping my car anyways. But still I've went through every break valve I used a pneumatic bleeder I gravity but I've done everything possible except for bench bleeding the master cylinder which I'm about to do right now but I'm pretty sure I have pinpointed what the issue is and I'd like all of you to weigh in if you think that this is accurate.

So I noticed when I was letting my car sit idle because for one of the bleeds I decided to have the car on thinking that might help. Well anyways I noticed that there was some sputtering going on in the engine It wasn't It didn't sound normal anymore. Well I just thought maybe the computer just needed to you know recalibrate itself or something so I just wasn't too worried about it while the brake issue continued with the pedal falling to the floor. Well I happen to catch a little bit of a video of a guy talking about fuel trim levels and I'm not very smart with cars I didn't know that all the stuff was connected started reading into it and realized that the brake booster gets its air or puts its air into the engine up to the air intake. So I'm thinking okay what does that mean Well I got my little computer out my cheap little one and open the diagram on the short fuel trim levels on banks one and two and I could actually push the brake and as long as I was pumping the brake I could actually watch the line staircased up from around -2 to +2 all the way up to 28 and then as soon as I would either let off the break or just hold the break to the floor that number would go back down and settle back at where it normally goes or normally is right now. So that means that instead of the air being held in the brake booster it's going into the air intake into the fuel injection right? Well as I'm telling the story to a mechanic I ran into it to the store he finished my sentence and said that that's what that was. So right now I'm getting ready to perform a pressures check on the system to see if that the booster holds it or not. But anyways I was not expecting to pay another $150 on the car part today but fun fun.

By the way there's anybody know if I can use a brake booster from a 2011 Chevy Impala and put it on my 2012 Chevy Impala?
According to AutoZone they're different but I don't know that I trust that completely.

 

[reubenswinks]

Looks like they are in fact different part #s from 2011 to 2012. You can use anything from 2012-2013 or the 2014-2016 impala limited. For part refrences I almost always use rockauto.com. You can search your car and find the part you are looking for, then click on the part number (blue hyperlink which says "buyer's guide" when hovered over) and it will show you which vehicles it is compatible with.

Sounds like the diaphragm in the brake booster is bad. When you actuate the pedal you shouldn't be introducing any air into the engine as that should always be under vacuum. Weird that went bad right when you changed brakes. I suppose all the priming/bleeding could have caused it to go bad. Better now than when you are driving down the road though I suppose.

 

[RickCoMatic]

I think you're not dealing with bubbles and major air pockets after all the bleeding of brakes you have done.
I strongly suspect the Brake Master Cylinder's Main Hydraulic Seal.
The Main one which is supposed to Pump the Brake Fluid ... OUT ... allow for Fluid to pass from reservoir into system, ...
But, ... NEVER ... in the opposite direction causing Hydraulic Pressure LOSS.

If Brake Fluid is seeping past the Main Hydraulic Seal under pressure, .... after purging and bleeding ... allowing the Pedal little if no resistance as pressure fails.
The Master Cylinder's bad.

""So that means that instead of the air being held in the brake booster it's going into the air intake into the fuel injection right? ""

NO. Abb-so-freakin'-loot-leee, ... NOT!
Wrong.

 

[reubenswinks]

""So that means that instead of the air being held in the brake booster it's going into the air intake into the fuel injection right? ""

NO. Abb-so-freakin'-loot-leee, ... NOT!
Wrong.

If the brake booster has a leak in the diaphragm it absolutely will allow air to enter into the air intake. Talking about the brake booster, not the master cylinder. Maybe you should do more research before you tell someone they are "
Abb-so-freakin'-loot-leee, ... NOT! Wrong."

Here is an article explaining how the brake booster works and what happens when it fails:

AGCO Automotive Repair Service - Baton Rouge, LA - Detailed Auto Topics - Vacuum Brake Boosters

AGCO provides overall lowest costs of vehicle ownership. We do this by providing extremely high quality automotive service, following the theories and practices of Dr. W. Edwards Deming., Vacuum brake booster

www.agcoauto.com

If you dont want to open it, read this snippet:
"A ruptured diaphragm also allows, atmospheric pressure to enter the intake manifold. This creates a vacuum leak and causes the fuel/air mixture to lean out. Other than hard braking, another symptom is an engine misfire at idle, when we depress the brake pedal. "

I think you are on the right track with the brake booster. Often times when a booster goes bad, it is due to a leaking master cylinder though also (brake fluid deteriorates the diaphragm), so I would double check that it isn't leaking.

 

[RickCoMatic]

This fellow needs a Master Cylinder.
No AIR enters the FUEL INJECTION.
Clear this up before making an issue with anyone trying to help this gentlemen.

Manifold Vacuum operates the Booster.
Air gets drawn into the engine's combustion chambers.
Fuel is injected into the cylinders.
No air enters FUEL Injection.
Hook-up whatever you like that is operated by Manifold Vacuum.
AIR does NOT enter FUEL INJECTION.

Mr. Wideman is the member who requires instruction and assistance.
This thread began with him saying: Pedal went to the FLOOR.

Brake Pedal to floor.
Pedal to Floor?

Please assist Mr. Wideman with his Master Cylinder problem.
After he gets some Hydraulic Pressure in the Brake System would be a good time to bring-up manifold vacuum assisted braking.
Agreed???

 

[reubenswinks]

Alright...I guess if you want to be that technical and not actual try to understand what he is saying, then yes, you are correct. Air does not enter the fuel injection. Obviously it was not worded correctly, but he is trying to understand why the fuel trim is being changed by the pedal actuation. Understanding that, it IS because there is unmetered air entering the intake from the vacuum booster. I'm not here to argue whether or not he may also need a master cylinder. I think that is very likely, and was likely the cause of the brake booster going bad (as I mentioned in my post). I was just answering his question about his fuel trim observations and you leading him to think there is nothing wrong with the brake booster, when there more than likely is.

 

[RickCoMatic]

Exactly.
Right on the nose.
I like your style.
I didn't mean to mislead anyone about the Brake Booster.
The one I'd have him install comes attached to the new MC.

If someone was to tap my shoulder and ask what to do; I might say let's try kits.
In the Forum, ... I'll never recommend kits.
Brakes ain't no foolin'-uh-round!

You should be moderating!

https://www.napaonline.com/en/p/NBB509089?cid=paidsearch_shopping_dcoe_google&campaign=GSC-Brakes&campaign_id=8659198719&adgroup_id=106304766654&adtype=pla_with_promotion&gclid=EAIaIQobChMI8YTV-K6f8wIV1frICh1xLwZ2EAQYBSABEgJzh_D_BwE&gclsrc=aw.ds&&__cf_chl_jschl_tk__=pmd_MYKJvEorTXKKhfWnDzionl7X0gIarkovhY73FBcD12w-1632753027-0-gqNtZGzNAzujcnBszQzR

 

[Wesley Wideman]

Hey guys, I am very sorry for not responding in a timely manner. Been dealing with don't personal crap either with my health or the health of close family. I'm only 38 and am over watching my closest people get old or die. Anyways, I really appreciate everyone's comments and detailed pics. Even if you guys don't agree with each other it is all helpful in one way or the other to someone with little knowledge, although my knowledge level is increasing substantial with all the reading and trial and error. So no offense to anyone but I am more inclined to go by the word of reubenswinks because he had been helpful in the past. I have the new/used, with a guarantee and warranty, brake booster on the vehicle. I was not at any point losing fluid unless I opened a bleeder valve. I am hooking everything back up tonight. So in order to get access to the brake booster I had to remove the intake manifold. There was just no other way for me to figure out how to do it without doing that. While I was in there I cleaned out the upper manifold that detaches from the vehicle and then I cleaned down in the lifter areas on the ones with closed lifters that is. I am putting on new gasket now. Here are don't pics. I will update you all even I'm back on the road or run into another mind bender. LOL Thanks again guys.

 

[SoRealz]

Hey guys, I am very sorry for not responding in a timely manner. Been dealing with don't personal crap either with my health or the health of close family. I'm only 38 and am over watching my closest people get old or die. Anyways, I really appreciate everyone's comments and detailed pics. Even if you guys don't agree with each other it is all helpful in one way or the other to someone with little knowledge, although my knowledge level is increasing substantial with all the reading and trial and error. So no offense to anyone but I am more inclined to go by the word of reubenswinks because he had been helpful in the past. I have the new/used, with a guarantee and warranty, brake booster on the vehicle. I was not at any point losing fluid unless I opened a bleeder valve. I am hooking everything back up tonight. So in order to get access to the brake booster I had to remove the intake manifold. There was just no other way for me to figure out how to do it without doing that. While I was in there I cleaned out the upper manifold that detaches from the vehicle and then I cleaned down in the lifter areas on the ones with closed lifters that is. I am putting on new gasket now. Here are don't pics. I will update you all even I'm back on the road or run into another mind bender. LOL Thanks again guys. View attachment 165308 View attachment 165310 View attachment 165311 View attachment 165312

So, what happened with the impala? With the brake situation ?

 

[Wesley Wideman]

So, what happened with the impala? With the brake situation ?

So the booster was definitely the root problem but even once I installed the new one I couldn't get the lines cleared on my own. I ended up taking to a shop here in town and he went through like a gallon on fluid getting the lines cleared off air. It finally worked and I was good to go. Unfortunately 2 years later and she is back on my garage because my power steering went out and so I am replacing the rack.

 

[GrizChev]

So the rack was inspected and found to be bent? That sux. Getting a new pinion to match, right?

I have to tell you that the ABS bleeding and the Rack-Pinion I would take to a shop too. I'm too old to mess with it, especially in winter where I live.

 

[Sammo1984]

NHTSA has released an updated Service Bulletin for proper brake bleed procedure. Down load PIC5468D or print it off from their site. Follow step by step instructions then report back on completion.