Before starting the slippery slope of throwing new parts at the problem, I figured I would ask the wise people of the forum for some advice.

The brake lock-up seems to be a somewhat common issue with the Nissan family, or so my Google-fu would suggest. There are a bunch of comments on this site about it as well, but few had a definite solution.

Important details to note:
About 3000 miles ago I replaced the original master cylinder with a rebuilt one, which worked great even on a long road trip across the state 2 weeks ago.

The issue:
On my way home from work last Friday as it was 95+ degrees here and I was stuck in stop and go backroads traffic I started to feel the car dragging. The longer the engine ran (regardless of me pushing the brake pedal) the tighter the brakes got, until I forced it off the street into a parking lot. After sitting for a bit the brakes let loose and seemed to be fine.

I got back on the road and after about 5 miles they started to lock up again. It seems it’s a time thing, not related to me actually pushing to the pedal.

Symptoms:
The pedal is up (in normal position) not stuck down
The pedal pushes normal at first and gets harder as pressure builds, until it is brick solid.
I only lifted one front wheel to rule out a locked up e-brake, but it seems all brakes are locking up at once (isn’t dragging to one side or slipping a select wheel).
I pulled the vacuum hose off the booster, which sounded like I opened a soda can, but the brake pedal still felt the same.

My online search have revealed there are most likely four possible culprits: the master cylinder, the booster, the block which distributes the 60/40 pressure (not sure what it’s called) or a mysterious check valve people talk about but I have no idea where it is.

Any ideas on where to start or how to trouble shoot further?

How long did it take for them to loosen up after you stopped? if it takes a good amount of time, you may want to try jacking up the car one side at a time and see if all four wheels are locking up. I have had calipers on my motorcycles go bad and cause this type of issue. if it is all 4, my first thought would be to re-bleed the lines. If that didn't work, my gut would have me looking at the booster/master cylinder.

It takes about 20 - 30 minutes or so of the engine being off to release enough to roll. Plenty of time to check all 4 wheels, especially if the engine is on. Someone else also mentioned the calipers as a possibility, but it didn't feel like one wheel dragging solo. And all 4 calipers going out at once seems unlikely to me. But I will remove all doubt and try. I'll give that a shot when I get some time.

checking each wheel could also lead to something else. if it is only the front or back locking up the booster should be fine, but i would then suspect the master cylinder or "proportioning valve".

Proportioning valve! That's what it was called! So, i need to jack the car up to eliminate multiple possible culprits. Thanks for the advice! I'll see if I have time tonight. If not this weekend for sure.

if you're still trying to sort this out, here is something i ran across.

http://www.seattletimes.com/nwshowcase/ ... mple-test/

It is still a problem. And thank you!

I got in a wreck a few weeks ago (RIP I30) and have been too sore/busy to deal with it. I appreciate all the advice and plan to address this before parking the car for winter. The best part is if it is indeed the master cylinder, that's under warranty.