'77 MC Diagnosis confirm?

[sggoat]

If you are going to replace-Check BMA parts-they have Aisin hydraulics for a decent price.

 

[TheHardWay]

As part of the MC/booster diagnosis steps, I wanted to pull the check valve off the booster and test it. In the diagram drawing it appears to be threaded, but when I tried unscrewing it I could see that the hose connector pipe was going to hit the mounting bolt, so I stopped.
Is the check valve a screw on/off part?

 

[TheHardWay]

'77 MC Diagnosis Confirmed!!!!

I have noticed ALOT of threads that have no End of the Story, which is really annoying, so I intend to see this one through!
In our last episode I had ordered a NAPA replacement MC and was waiting for my 4 day weekend to install it. This is what I got, including the bleeder tubes and threaded inserts. Okay, ready to start!

 

[TheHardWay]

I used a baster to remove the brake fluid from both reservoirs, then loosened the four nuts holding the MC to the booster. Removed the two outlet lines, the four loosened nuts and sensor connectors and pulled the MC away. Gulp, no turning back now!

 

[brian]

if you currently have an oem master, you can swap ressies and caps.

 

[TheHardWay]

You can see a small puddle of old, dirty fluid in front of the booster pushrod seal. There is wrinkled paint on the booster and firewall where splatters did their thing over the years. The front outlet nut had been compressed a bit and didn't want to come out after it had been unscrewed all the way, so I unscrewed the copper nut and finally worked it out. I had a feeling it was going to be a problem later.
You can see how the PO had Teflon taped all the threads. I stripped that off and wiped out the booster puddled and proceeded to the new one.

 

[TheHardWay]

After screwing in the sensors, I set the MC on a bench, level. The instructions are easy to follow. This is the 'bench bleed.' I filled each reservoir 3/4 full and waited for the bubbles to appear. Took five minutes, but they did make their appearance. After watching them for 5 minutes I screwed in the valve bleed plugs and tubes and bent the tubes into the reservoirs. Bubbles continued for a little while. Then I slowly pushed a wood dowel against the MC piston and watched more bubbles come through the tubes. The back reservoir bubbles first, so I had to push farther to get the front reservoir to force bubbles out.

 

[TheHardWay]

Following the instructions, I set the MC on the four threaded bolts, lightly screwed two nuts on, and the fun began. The front brake line outlet nut would not slide down into the opening, so I filed the compressed tip until it finally went in and I could screw it into place.

 

[TheHardWay]

I wasn't sure the on the fly fix of the outlet would work, but I finished reinstalling the lines, brackets and sensor wires, topped up the reservoirs and reached into the cab and pushed the brake pedal. Felt firm! Time to take a drive...

 

[TheHardWay]

Woo hoo! I got firm brakes, finally! Half an hour after my drive my wife returned from a meeting and I had her drive it too. She gave it two thumbs up!


This is what the inside of an old, tired MC looks like. Someday, if I feel like it, I'll disassemble it and check out the cylinder walls for possible rebuild. Bonus pic to follow.

 

[TheHardWay]

I bought Zeke Jan 2. I knew when I test drove him the brakes were soft, so after I replaced the clutch MC (leaking into cab) I concentrated on diagnosing the brake system. IH8MUD has been a treasure trove of info for anything and everything Landcruiser, but you have to search, search, search to find the nuggets.
My point to this thread has been to show all you newbies (like me) that you don't have to spend a lot of dough to make your cruiser a safe, reliable vehicle. Those of you who have seen the Meet Zeke and this thread know I have plenty of work ahead of me, but finishing a project like this (total cost: $40 for 4 cylinder rebuild kits, $68 for MC, $15 for brake fluid, hose and gloves) gives me a great feeling of accomplishment AND confidence that since I don't intend a total restoration, I'm not facing a money pit of discouragement. I just want to get my groceries at Walmart, even if Zeke has to crawl over zombies to get them!
This photo is for those who asked for more from the Meet Zeke thread. Hey, everybody likes to see what's inside your cruiser!

 

[brian]

you're missing the drivers side defrost duct and cowl vent drain line.

 

[TheHardWay]

you're missing the drivers side defrost duct and cowl vent drain line.

Thanks, it will go on my list of things to do.

 

[Pin_Head]

You can see how the PO had Teflon taped all the threads.

Congratulations!

I noticed the teflon tape, but I wasn't going to say anything. Since it was the PO that did it, teflon tape is only for sealing tapered pipe threads. It is counter productive for flare or compression fittings.

 

[TheHardWay]

Thanks, Pin_Head. IMO, getting those brake cylinders unfrozen and working again was the key to this problem. I wonder how many of us DIYers have given up ever getting the shoes adjusted without realizing how critical those cylinders are to the adjustment procedure. There's no way the two POs touched them, and I was shocked at how those pistons that are supposed to move back and forth could have been so petrified and hard to bust free!