Crazy brake problem after5.3 swap.

Took her around the block a few times for the first check ride after many start-ups in the driveway to tweak and adjust stuff. Got on the gas a couple of times just because I couldn't help it. Awesome by the way! Anyway when I got back home the brakes locked up,pedal was down and wouldn't come back to normal position. I've got a brand new brake booster (stock). I disconnected the vac line from the booster and the brakes released and acted normal.Just wondering if anyone else had this problem. I've got a 1990 gmc xcsb with a 2003 5.3 4l60e out of a silverado. Also a car intake and a corvette cam. Just a mild street build. My booster hose is hooked up to the large port at the rear of the car intake. Is my engine making too much vacuum for the stock brake booster? My vacuum guage reads a steady 19" of vac. Thanks guys for any assistance.

You may need a need valve for the brake booster!

Thanks, what kind of valve do I need and what is it called? Thanks.

I don't know if it's fixed or not,only a good test drive wil tell. My 5.3 came with a pcv valve that had no check valve and I replaced it with one with a check valve. I'm thinking thats what caused the brake booster to lock the brakes,not sure though,anyway I put the non check valve back in and we'll see.

there is a valve for the brake booster. the pcv( positive crankcase ventaliation) is for the engine. i hope this clears anything up!

Thanks I'll search for it online. Preciate it.