Stiff brake pedal AGAIN

[fattest1here]

hey guys my 92 3.0 is having problems again. I changed the brake booster 2 weekends ago because my pedal was completely stiff. I changed it with a booster and Mc from a 94 v6. It has been great until Wednesday. Now the stiffness is back, but it's not completely rock solid. I bypassed the factory check valve line and still no change so I'm guessing the factory line is fine. What else can it be?

 

[TX_QtPi]

easy way to test the booster for vaccum pressure

Truck Off press the brake pedal several times.
Press on Brake pedal and HOLD. Start the engine.
If the pedal goes down slightly, operation/vaccum is normal.

If not, check for a vaccum leak, also booster may be bad out the box.

I found this too, not sure if you want to doo all this though
Brake Upgrade

 

[fattest1here]

Yeah this was a used booster and mc. How often do these things fail?

 

[fattest1here]

Will anything else cause the stiff pedal? Like a vacuum leak, bad wheel cylinder, frozen caliper? I'm just tired of throwing money at the thing.

 

[SR5Runner97]

Will anything else cause the stiff pedal? Like a vacuum leak, bad wheel cylinder, frozen caliper? I'm just tired of throwing money at the thing.

is it possible the MC you put in was a couple days from going bad? My girlfriends 88 22re has a horrible stiff pedal and never told me. I drove it and felt like I was gonna die. I think it's just her MC that's bad. Hopefully. But if you replaced a 22 year old part with a 20 year old part? I'd just spend the extra to buy a new one. with a warranty.

 

[fattest1here]

I agree but this is the very first time with all the cars that I have owned and worked on that has had a brake booster/mc issue. I just assumed that it was just my luck with this thing. I just checked all the hoses and the check valve in the booster line. Everything is fine. I did notice that when I pulled the booster line off the booster the pedal didn't change at all (the pedal still has a little bit of play in it, unlike the last booster I swapped which was rock solid)