Brake pedal it goes normal until close to the bottom and then continues about a quarter inch with a clunk at the bottom?

Sounds good, Chad. Take care and good luck. I will watch for your reply.

Joe

Okay, now that we have a good pedal, try to bleed the system. However, air in the system shouldn't cause the system to lock up. So, lets try to narrow it down. First, pump the brakes so the calipers lock. Once they do, open the bleeder on the caliper and see if the caliper releases. If it does, then we need to go further back. Close the bleeder at the caliper. Go the master cylinder, and apply brakes so they lock again and open the front steel line on the master cylinder and see if it releases. If it does, then something is bad in the master cylinder.

One other thought. There is a fluid control valve on the MC that's primary function is to control rear brake pressure. Did you reinstall it? I attached a picture of it.

Let me know.

Joe

PS: You did clean and lube the caliper slid pins, correct?

Then pressure isn't able to return to the MC. Try the test I suggested and let me know the results. It's either fluid can't return or you got bad calipers and the pistons are sticking.

Take care,
Joe

No problem. Let me know the results.

Joe

The valve may be the entire problem. It is what determines pressure to the rear. However, I have to be honest with you, I never saw one cause this. But, if the calipers release when you open the bleeder at the MC, that is my first suspect unless the new master cylinder is bad.

Was the vehicle doing the same thing prior to replacing the MC? If not, there may be an internal issue in the MC. There are two plungers. The one for the rear brakes may be bypassing fluid, causing the rear pressure to be low and causing some kind of build up of fluid which in turn doesn't allow the fronts to release.

Do the front brakes release when you open the bleeder?

If they don't release when you open the bleeder on the caliper, the problem is either the caliper piston is stuck or the slide pins are bad or not properly installed.