Master cylinder not pumping fluid to front brakes

[redroadster]

I pump it slow let it slow 10 xs and that usually bleeds it , the forward cyl/ reservoir is rear brakes back to frt.
Pedal goes to floor ? Dot3 fluid ?

The piston can seize in the cyl
The aluminum will corrode if dry alot of times
But it's not functioning , could blow a quick burst of compressed air in the exit port

[jasmith1975]

I pump it slow let it slow 10 xs and that usually bleeds it , the forward cyl/ reservoir is rear brakes back to frt.
Pedal goes to floor ? Dot3 fluid ?

The piston can seize in the cyl
The aluminum will corrode if dry alot of times
But it's not functioning , could blow a quick burst of compressed air in the exit port

Update #2: we now have working brakes Thank you for the help and tips along the way. I'm not 100% sure what the issue was, but a good bench bleed solved the problem. Before that I replaced the rubber hoses as they looked pretty dry rotted (although didn't see any leaks). I went with Raybestos BH36737 (stamped Sunsong) per the TechWiki and they fit great. The female ends are shorter than OEM Nissan so I didn't reuse the hose indexing clips but secured the hose with just the brake clips. BTW, flare nuts suck. A LOT of penetrant (PB, Liquid Wrench, etc), heat, good line wrenches and patience was needed to free them up. I can also confirm the Dorman 12701 Speed Bleeders are a good alternative to the Goodridge SB3824.

Although there's good info in the TechWiki already, here are the steps I took to bleed the Tokico dual circuit MC on a '68 2000. For some reason bleeding it on the car didn't work:

1. Drain all brake fluid from MC (a turkey baster or fluid transfer hose works)
2. Remove clevis pin, clip and pedal return spring to disconnect MC pushrod from brake pedal. Tip: secure a bungee cord between the brake pedal and steering wheel to keep pedal off the floor or brake lights will stay on
3. Disconnect two hard lines from bottom of MC with 11mm line wrench
4. Remove 2 nuts and washers securing MC to firewall with 13mm wrench. A small 1/4" socket and ratchet helps with the bottom nut. The top nut is a little tricky and tucked behind the front brake reservoir. Loosen the reservoir clamp and turn reservoir 90 degrees for better access with a open ended wrench.
5. Remove MC from the car being careful not to catch/bend the brake lines. Pay attention to any shims for remounting to the firewall.
6. Clamp MC snug in a vise with blocks of wood to protect it from the jaws. Install 3/8"-24 hose barbs where brake lines were disconnected and attach 1/4" clear tubing routed back up into the correct reservoirs. The Dorman 14151 MC bleeder kit works great for this.
7. Add new brake fluid (I used Prestone Dot 4) to the reservoirs then slowly/fully move the pushrod in and out until there are no more bubbles. Tip: slide a sturdy screwdriver through end of the pushrod to help move plunger.
8. Attach another 1/4" clear tube to the side bleeder valve routing to the correct reservoir. Open valve and again move the pushrod, slowly in and out until there are no bubbles. You can keep the tubes from step 6 attached when doing this. I did each bleeder valve separately, but you can probably do them both at once. When there's no more bubbles, you're done.
9. Tighten bleeder valves, remove tubes and it's ready to go back on the car. I kept the hose barbs and tubes to the reservoirs connected to transport and reinstall. Don't forget to keep the reservoirs topped off when bleeding the brakes.

[MattC]

Thanks Jared!!

[Gregs672000]

Thanks for posting your detailed solution... that kind of info at the end of a thread is always appreciated.

[Loy]

Glad everything workedout!

[RonnyB]

What is your recommendation regarding the brake safety switch? Do I need a tool to block one side at a time? If so, where is it available?

[Gregs672000]

I'm not aware of anything special that needs to be done with the switch, but then again I've never had one! Might check the online manual in the wiki and see if anything is mentioned.

[Solex68]

Thanks for the thorough write up Jared.

[Dster]

Is there a side bleeder valve??? I just did the bottom two- did I miss something? Thx!

[redroadster]

I'd try filling the frt.line with fluid then have it in the tank ,also it sometimes helps to pump it rapidly ,or try remove the line going back to the tank and hold your finger over it ,so as it has to draw fluid or it it seized you need 2 people to accomplish this , bleed both lines at the same time which let's the pistons go to the very end