Topic: Bad booster?

[lilbuddy]

On my 02 tacoma the brakes absolutely suck. I just want a second opinion on what it could be... Im not 100% on it.

Anyway, A month or two back, my rear end broke so i had it all apart and the brake line off and i just had it sitting there. It sat in my garage for about 2 weeks and there was no brake fluid in the reservoir by the time i went and put it all back together. I bled the brakes a bunch and got a bunch of air out. There still was a little air, but not a significant amount. After I did everything with the rear end and when i took it for a drive, I noticed that I lost about 60% of the braking power that I had before. The only thing I did was switch out the axle shafts and also had the brake line undone for 2 weeks.

Now the thing is, when i slam on my brakes the pedal is really hard and you can hear a hissing noise coming from the booster. Also... the motor kinda bogs down a little and starts running rough.

I am thinking it is the booster but I am not 100%. What I am going to try to do tomorrow is take off the ebrake cable and try bleeding the brakes some more to see what happens. I dont think its the booster because before the truck stopped on a dime before i touched it. I am pretty sure it has smething to do with the rear end.

Im probably jumping ahead of myself by even asking but I want to get someone elses opinion before i go and buy a new booster (if thats the problem.) Like I said though, I am pretty sure it has something to do with the rear end and it coincidentaly happens that the booster makes a bunch of noise. It used to make noise before also.

Any thoughts?

[fordh8r]

I would certainly double check the bleed job and make certain of the rear brake adjustment so the pedal won't have to travel as far and might make the difference with the booster.

keep in mind too, when you bleed the brakes the pedal travels further than normal and may have possibly damaged the diaphragm in the booster. Slim chance but maybe possible.  Does the booster hold vacuum? it should as long as the check valve is good. Also check the vac source for any possible issues.

Hope you find the problem.    MCR is real close. You're going, right?

[lilbuddy [OP]]

I would certainly double check the bleed job and make certain of the rear brake adjustment so the pedal won't have to travel as far and might make the difference with the booster.

keep in mind too, when you bleed the brakes the pedal travels further than normal and may have possibly damaged the diaphragm in the booster. Slim chance but maybe possible.  Does the booster hold vacuum? it should as long as the check valve is good. Also check the vac source for any possible issues.

Hope you find the problem.    MCR is real close. You're going, right?

Yeah I do know that the pedal goes further... Ive bled brakes many of times 

Do you mean hold vacuum as in when i turn the truck off that 3 days later i can get in it and hit the brakes once and it will have some pedal? If so, yes.

I am goin to MCR regardless. Ive been drinving like this for 2 months. I just am sick of having to give myself a lot more distance in order to stop.

[fordh8r]

Yeah I do know that the pedal goes further... Ive bled brakes many of times 

Didn't mean to sound like you didn't know what you were doing here, sorry. 

Do you mean hold vacuum as in when i turn the truck off that 3 days later i can get in it and hit the brakes once and it will have some pedal? If so, yes.

Pretty much. Although it could leak with the pedal down and not at rest.

I am goin to MCR regardless. Ive been drinving like this for 2 months. I just am sick of having to give myself a lot more distance in order to stop.

Cool! 


Kinda starting to sound like you'll be needing a booster. 

Just for clarification, you also hadn't replaced the rear shoes, correct?

[lilbuddy [OP]]

No I did not replace the rear shoes....

Today I fiddled with the brakes some. Im thinking that either theres air in the master thats for some reason making it stiff or the booster is bad. I think that the booster is bad. Before I was able to lock up my brakes with ease. Now, it seems like none of the brakes are even working. Pretty weird that it happens right when I broke the rear end though. Same thing happened to my brother, we had to put a new rear end in his jeep and after we did that the brakes were/are crap BUT when we turn off his jeep to see if the booster changes anything with the motor on or off, it didnt. Now with my truck when I turn it off the brakes are noticeably worse then with it on.

[fordh8r]

No I did not replace the rear shoes....

Ok, cool. Just makin sure I was clear. 

Now with my truck when I turn it off the brakes are noticeably worse then with it on.

Is this noticeable immedeiately after shutting off the engine? or do you mean after 2-3 pedal applications with the engine off?   

If it's immediate I would likely say the booster is leaking. If it's after 2-3 apps I would say that is pretty normal.  Maybe see what happens if you hold the pedal down with the engine off and see if it bleeds off completely like that. 

[THK Matt]

Ok, cool. Just makin sure I was clear. 

Is this noticeable immedeiately after shutting off the engine? or do you mean after 2-3 pedal applications with the engine off?  

If it's immediate I would likely say the booster is leaking. If it's after 2-3 apps I would say that is pretty normal.  Maybe see what happens if you hold the pedal down with the engine off and see if it bleeds off completely like that. 

thats what mine did in my truck and i had to replace my booster.
hope you get it fixed LB.

[lilbuddy [OP]]

Ok, cool. Just makin sure I was clear. 

Is this noticeable immedeiately after shutting off the engine? or do you mean after 2-3 pedal applications with the engine off?   

If it's immediate I would likely say the booster is leaking. If it's after 2-3 apps I would say that is pretty normal.  Maybe see what happens if you hold the pedal down with the engine off and see if it bleeds off completely like that. 

Happens right after i turn the engine off....

and, when I am on the brakes still rolling and turn the engine off, the get worse also.

Id say its bad. Dammit

[fordh8r]

Happens right after i turn the engine off....

and, when I am on the brakes still rolling and turn the engine off, the get worse also.

Id say its bad. Dammit

  When it works like it should, it should get about 2-3 normal feeling applications once the engine is shut off ( inherent safety feature in case the engine should die unexpectedly while moving with the help of the check valve which locks the vac in the booster for this reason). If it's bad immediately I would say booster is no good.  Unless, the check valve has failed. But if the check valve had failed you most likley wouldn't hear the hissing noise you described. 

[lilbuddy [OP]]

  When it works like it should, it should get about 2-3 normal feeling applications once the engine is shut off ( inherent safety feature in case the engine should die unexpectedly while moving with the help of the check valve which locks the vac in the booster for this reason). If it's bad immediately I would say booster is no good.  Unless, the check valve has failed. But if the check valve had failed you most likley wouldn't hear the hissing noise you described. 

Yeah thats what I thought. The only thing that was throwing me off was the fact that its noticeably different when the motor is off but that makes sense that the check valve would be bad since its bad right when the motor is turned off.

[fordh8r]

Yeah thats what I thought. The only thing that was throwing me off was the fact that its noticeably different when the motor is off but that makes sense that the check valve would be bad since its bad right when the motor is turned off.

I suppose if you really wanted to....you could just replace the check valve for a quick and easy check. Or you can put vac. to the 'booster' side of the check valve to see if it holds. If it holds vac. then that's not the problem. At that point I would say booster.