Any ideas would be helpful. I have a 1972 240Z which I put up on blocks for the winter so I could get my other car into the garage also. Two weeks ago I took the 240Z off the blocks and had to jump start the battery to get the car started. Let the car idle awhile and backed it down the driveway. Drove it up the driveway and shut it down. Would not restart, needs a new battery. Not the problem though, went to push the 240Z back into the garage and realized the brakes where frozen and the brake peddle cannot be pushed down. Took the front wheels off and both calipers are frozen. Opened a bleeder and was able to pump the brake peddle but the calipers did not do anything and as soon as I close the bleeder the brake peddle cannot be depressed, any suggestions would be helpful. Thank you.

Sounds a little crazy.....the calipers stay locked when you open the bleeders? Or do they release with the bleeders open but, when you press the brake pedal down,(with the bleeders closed) stay stuck after you release?
If the calipers stay stuck/locked even with their bleeders open, they need service or replacement. If the brakes are staying stuck locked after you push the pedal and release it, then the master cylinder is bad. There is a small port inside the MC that allows pressure to release and fluid to flow to and from the reservoir when the pedal is released. That port is exposed when the plunger rod retracts fully to the rear, which happens when you release the pedal. If that port becomes clogged or rusted shut, or if the plunger is not retracting fully when the pedal is released (due to dirt or improper pedal/pushrod adjustment) then the fluid pressure in the brake system will not release when the pedal is released.
Brake fluid absorbs water out of the atmosphere and becomes contaminated with time. When cars are stored for long periods, especially when the brake fluid is not replaced every two years (the standard service interval), you often get rust forming inside the system, which can cause seal failure, clogged ports, and stuck calipers.

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71 on a rotisserie, two more in pieces in my shed...and a 69 1600 waiting for me to get to it

I agree with everything Mark just said. Before you pull the master cylinder tho, try pulling the calipers off the rotors, then compressing them with a 4" C-clamp. You can't compress liquid ~ if they won't budge with the C clamp, your problem *should* be the master cylinder, as Mark described.

Frank

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1970 240Z

Thank you I will try that. When the bleeder is open the calipers still do not move but I am able to push the brake peddle and fluid does come out. Once I close the bleeder I am unable to push the brake peddle and the calipers still do not move. I still have not checked the back brakes for all I know they could be frozen also?

Yeah, the rear brake drums can be a pain to take off.

Be sure to unfasten the handbrake clevis pin (cleavis pin?) at each brake and compress the shoes before trying to remove the brake drums.

If the drums won't come off, try rapping the center of the axel with a ball peen hammer to break the rust. Be careful not to strike the actual aluminum brake drum itself (it's actually safer to use a short steel dowel against the axel, then strike that with the hammer, instead).

If that fails, you can actually insert bolts (forgot what size) into the brake drums, and turn them down until they press against the backing plate and pry the drums off.

HOWEVER ~ having said all that, one Z which sat x20+ yrs simply refused to let the brake shoes come off, regardless of all my personal efforts. So there are no guarantees!

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1970 240Z

If you have the bleeder open and you push fluid out, then the calipers are seized, to verify, take caliper off and see if you can sqeeze the piston back in with bleeder open. Then try with bleeder shut and if it doesn't push in the brake hose is collapsed inside. If all that seems normal then I would look at the MC. Siezed calipers can be taken apart cleaned and put back together with some new seals. If the pistons are pitted...NO good, discard.