77 Brake Booster Question for newbie (1 Viewer)

[texex92]

I have recently purchased a 77 LC with front disk brakes. The brakes work well but the brake pedal is extremley hard to push down.
The vaccum line was disconnected from the brake booster. I suspect that is why the brakes are hard. I reconnected the vaccum line last night. It seems to have helped somewhat but you can hear a hissing noise when you press the brake pedal. It appears there is a leak in the vacuum line and or booster. Can you tell me what steps i should follow to isolate the problem or determine if i need to replace the booster. Is there a way to test the vaccum on the line to see if it is sufficient? What should it be?

Should i expect the brake pedal to be somehwat stiff but not hard to push or are the always stiff?


Any thoughts or direction where to look is greatly appreciated .

 

[NikP]

Do you have a vaccum tester/gauge? Sometimes you can get one via the loaner program at the local parts store.

Disconnect the booster from the intake/carb and hook up a tester/gauge. Pump up the tester and see if the vacuum gauge stays up. If these a leak you see the gauge drop and you'll know you need to replace it.

Also check hoses for vacuum leaks.

 

[FF LC FREAK]

If the vacuum line was disconnected from the booster when you bought the rig, and it started hissing when you reattached it, that's a pretty good indicator that your booster is bad. There is a diaprham inside that uses vacuum pressure from the engine to assist in pushing the push rod into the master cylinder. When the diaphram rips, gets brake fluid on it, or just plain deteriorates, you will get a vacuum leak. Not only does it keep your booster from working, but it also creates a nasty vacuum leak for your engine (which is a bad thing). There are a few places that stock rebuilt boosters (SOR or possibly Mark's Off Road), but they are big $$$. You could also have yours rebuilt be someone like Booster Dewey. However, when mine went out, I got one from a junk yard for $45 (from an early 90s mini truck) and it has worked perfectly for the past 5 years. There are lots of options for junkyard boosters - fj60s, mini trucks, and others. Do a search on here and you can find lots of different boosters that can work.

Oh, and welcome to Mud!

 

[Michael Hanson]

Any leaking fluid inside cab firewall or in engine compartment? Still hard as he....brake pedal now that its hooked up or weak brake pedal? Hard is booster, soft-mushy master brake cylinder or leaky hose to brakes. Mike