Hello,

First off I'm new to the forums, spent last hour reading through trying to see if this was already an issue for anyone else or if it was answered. But i cant seem to find it or my issue. Any ideas please help!

Trying to figure out where i'm losing break pressure in my lines. Don't see a single leak under the car. I can pump the breaks, and get pressure if i keep pumping. Once i let go after about 3-4 seconds i lose all pressure that has built up. Can rebuild the pressure by repumping just not sure where the issue could be or how i could test this to find out with minimal mechanic experience, and normal garage tools.

 

First check the brake fluid level to make sure it hasn't dropped. A rear wheel cylinder leak with drum brakes may not show itself. If the car has no leaks, and has had NO recent brake work done then it needs a master cylinder. If it had brake work done, I would try a bleed first.

 

Rarer, but can still happen is a brake booster problem where a vacuum leak or weak diaphram in the booster will cause pressure to drop and result in a squishy pedal. Do a smoke test and/or vacuum test to rule it out.

1st check the fluid level and remember Low = Leak. Check front calipers and rear wheel cyls. If not there, then check lines. If no leaks found, then your master cylinder is shot and is allowing blow by resulting in the very problem you mention. Keep going with it, and eventually, you will end up a statistic - hopefully not a dead one.

 

You cant pump up a brake booster. If you pump the pedal and the pedal rises, more then likely its an internal leak on the master. If the booster diaphragm goes out, the pedal will not pump up. If the vacuum line came unhooked, the pedal would be solid.

A low fluid level can also mean the brakes are due to be changed. The only way the fluid level should ever read full is when you have all new brakes put in. You need to check for noticeable drops in fluid level.