Thread: No brakes after boost...

Finished my turbo install and took the car for a test drive to try to get the safc set.

Boost is set at 12psi. After getting on the pedal, my brakes are very sluggish and reluctant to work for a couple seconds! The only thing I can think of is the vac line on the manifold getting pressure instead of vac to operate the brake booster. It's only for a second or two, but I don't like it.

Has anyone else had this problem? If so, how did you fix it? A friend suggested a "vac globe"?

You press on the breaks as you are boosting? Are you using both feet?

It could be the check valve is leaking.

Where is the check valve? Maybe inside the actual break booster? The hose doesn't have check valve.

When I first noticed it I made a sprint down a sidestreet, and immediately went for the brake(not while boosting) to stop at a stop sign. The pedal went almost to the floor. Felt real mushy, then came back to life in about 2 seconds.

My friend mentioned a check valve, but there was just the hose running from the mani to the brake booster.

He said a vacuum globe would fix the problem, acting as a reservoir.

Never heard of ANYTHING like this, and leave it to me to be a pioneer for murphy's law.
But, at least this is the only problem I've encountered through this whole build.

Sorry for rambling.

You definitely don't want to loose your brakes. But I personally think it might be something else. Brake booster should help the breaks while the car is on, but your brakes should still work while the car is off.

Hence try pumping the brakes while the car is off, see if it does anything weird. Maybe you are running low on liquids, or got an air bubble in the lines.

There should be a check valve somewhere in the vacuum hose.

Hmmm, sounds like actual air bubbles in the system to me............If you disconnected the vacuum lines to the brake booster, some air might have got into the system and these bubbles can cause a fluctuation in brake activity.

Try bleeding the system before you buy any parts and see how it feels after.

The brakes grab if I press hard on the pedal. They work fine if I don't spin the turbo up much, or deccel before I hit the brake....when there is vacuum in the mani. That behavior is what made me think of the whole press/vac theory.

We put on new rotors and calipers, but we bled the sh*t out of those lines and topped the fluid off. So I don't believe there may be air in the lines. But I could do it again to be sure.

I also, looked for a check valve, and there's not one anywhere in the line. So I'm just gonna cut a new hose and put a check valve in. If THAT don't work, I'll give my friends "vacuum globe" thing a try.

you dont have a check valve plain and simple. you need a check valve in the line or you will not have brakes as you have learned already. you CANT just run a hose from the brake booster to the intake manifold it will NOT work.