bain

I DID search and couldn't find much info.. I have a 84 22R 5 speed. When I got the truck the brake pedal would pump with the truck off but when I cranked it the pedal would go to the floor and wouldn't build pressure. So I checked all the lines and installed a new master cylinder (bench bled) and it still has the same problem..I thought when a brake booster went out the pedal would get stiff. and there's no air in the lines..Whats the odds of me getting ANOTHER faulty MC or could it be the booster? Thanks

CAPTDASH

I am betting it is your brake booster. With it cranked up and the pedal working, taking a pair of vice grips and pinch the vacuum line that goes in the top of the Booster. If the pedal gets hard again like when it is turned off, you can pretty much bank on the booster being bad. You might as well get you a dual diaphram booster and put back in there. I promise you won't be sorry. Look for a 90ish 2 wheel drive Tacoma. It should have the same circumference booster as your single diaphram one. There won't be any difference in price at the salvage yard. If you want a single diaphram, I have one I will give you, if you pay the shipping. It works, I just wanted better brakes.

bain

When we messed with it yesterday we did that and the pedal got hard..Ive always heard when a booster is bad the pedal is hard when the vehicle is on...

CAPTDASH

Get you another booster. You could have a leak in the vacuum line as well. Your truck may even run a little rough due to the vacuum leak. Check your vacuum lines before ruling on the booster.

bain

no vacuum leaks, well..put in ANOTHER master cylinder..new wheel cylinders and brake shoes and adjusted the brakes and still no pedal :confused: should I be able to hear a little suction sound coming from the LSVP?

CAPTDASH

With your truck running, pull the vacuum hose off the brake booster. It should stall your truck or maybe even cut it off. I can't remember. You can tell if it is pulling vacuum like it is supposed to though. You changed all that stuff and none of that was what i suggested to you. I continue to believe it is your brake booster. I have one I will send you if you pay the shipping. I know it works. It is a single diaphram. I replaced it with a dual diphram that works great. That is my suggestion to fix your problem. I can't guarantee that is your problem though. Maybe some of these other guys can throw in 10 cents worth.

ChefYota4x4

iTrader: (5)

Captdash is giving you solid, complete info. You're running a 22r, so I'm not sure where it hooks up to the intake, but same principle as my 22re, I would think. Remove the booster hose from the intake, plug off the hole in the intake you just created(I used a brake bleed valve plug), then test your pedal play/stiffness. You will have no power brakes, so be careful, but nonetheless, ...you should be able to then verify the booster/rule out a vacuum leak at the intake due to bad hose. I THOUGHT I had a bad booster due to some issues I had, ..... even had one ordered up.... and as I was ready to go pick it up, someone like Captdash said, "HOLD UP, try this", ...and I realized that I had the same issue with my pedal play/softness as before, ....which ruled out the booster being bad(VERYYYYY rarely do they go out). This doesn't mean you're free from 'booster problems', lol... but it's a good place to start checking.

bain

with the truck cranked the pedal is dead. I pulled the vacuum line off the intake and capped it.. the pedal got stiff and when I uncap it the truck died. I'm hearing from a few different forums and some say when this happens the booster is good and some say the booster is bad...


and Im bout broke from replacing parts...If its the booster ill probably save up for the dual.. but I really appreciate your offer Captdash

CAPTDASH

Hey man I just don't know what to tell you. You got vacuum like your supposed to. So I am going to say it is the brake booster. Again, i got one I know works I will give you. It will cost you about 10 to 15 bucks in shipping if you want to try it. You can have it. No charge. You can't beat that. Just trying to help you out.

Otherwise I just don't know. The BBs do NOT normally go bad. You have replaced everything else, so my suggestion is replace the booster. I am sorry I can't any more than that. Good luck.

bain

Im going to work on it again Sunday..If I cant get them working I may just take that booster from you..I just hope I can get my booster off..My shock hoops are about a inch from it..

CAPTDASH

HHUUUUHHHH, your shock hoops are so close to your BB. I cannot imagine what kind of set up you have. You are starting to make me wonder if we are talking about the same thing. The booster is mounted to the firewall and comes thru to connect your brake pedal. I went and looked just to be sure. I can't imagine your shocks being in the way.

Anyway, just ease your master cylinder off. Don't break your brake lines loose & don't bend them or brake them. They will flex enough to slip them off the studs on the BB. Take the pin, 4 nuts and return spring loose on the inside firewall. Make sure and don't unhook the return spring if you can't see where it comes from. My hands are so big I couldn't hardly get that damn spring hooked back to its little hook under the dash. Anyway, please feel free to ask any questions and let me know if you need some help.

By the way, did you bench bleed your master cylinder when you replaced it? If not, you may have air in the MC itself. Just a thought. I didn't bench bleed mine, but I did basically the same thing with it mounted on the BB. DASH

bain

Yea we are talking about the same thing..This is the previous owners set up..and yea...I bench bled the MC.

bain

I worked on bleeding the brakes some more this morning..now the truck will actually stop..but brakes still suck. with truck running= i hit the brakes the first time and it goes to the floor and I hear the front calipers slap the rotor..hit them a second time and I have better brakes...so at least they are pumping now.. The booster IS working and so is the check valve..It almost feels like I have V6 calipers and not enough pressure to work them or not enough stroke in the booster..I'm just trying to eliminate things before I have to wrestle with changing the booster..