Trevor Mohler

So i just traded my subaru for another 4Runner. this one is a 92 stick with a 3.0. the brakes were extremely hard to press like the booster wasnt hooked up to vacuum and there was a hissing when you pressed the pedal down. i checked the fluid and the vacuum hoses and theyre all good and vacuuming. then the next day my 93 auto runner also with a 3.0 started having the same exact problem like womens periods syncing. i checked to make sure all the vacuum lines and fluids were good and i dont really want to buy two new brake boosters. any ideas to try please?? thank you!

akwheeler

the hissing you are hearing is a vacuum leak, if it only happens when you push on the brake pedal it means that your brake booster is leaking.
there is no good news here, if you have no brake assist you need to replace the booster.
The second one I would wait until you have signs of either poor brake assist or the engine stumbling when you hit the brakes.

Trevor Mohler

the engine hasnt really struggled when i press on the brakes, it just goes up about 2-400 rpm

akwheeler

your idle shouldn't change at all when you hit the brakes, you have a vacuum leak from the booster, if it is running rich in the first place the unmetered air going in will increase the rpms without the stumble.
it all depends on how bad the leak is, but if you have a hard pedal that doesn't go to the floor and as you say you really have to press hard on the pedal to stop you need a booster. There is nothing to "try" unless you "try" getting used to driving with poor braking and risk and accident.