bleeding brakes

[88SXT]

I'm in the final stages of getting my 88 ranger running again, trying to bleed the brakes and getting no where with the front calipers. When we push the pedal down and crack the bleeder valve we get a small hiss of air, but after several minutes with no pedal pressure and no fluid from the bleed screw I pulled it out completely hooked up my vacuum pump and tried that way . It will hold a vacuum but no fluid. I thought maybe it was a clogged line because it sat for two years so I pulled the hose off and had my buddy depress the pedal, fluid trickled out, the caliper itself is free of obstruction because I checked that too, and the banjo bolt isn't clogged. However, when I had the hose off I put my fingers over the opening while my buddy pulled the pedal back out and could feel a major vacuum being created in the lines as the pedal was being reset, I figured there would be a little vacuum but no that much.

Anyone have any ideas what could be causing this? I did notice that the gasket between the brake booster and the master cylinder is leaking but I didn't figure it would affect it enough to make bleeding impossible thus far.

 

[ab_slack]

I assume you had the top off the brake reservoir?

Collapsed rubber brake line? They may look fine but can collapse internally. They can block, act as one way check valves. I went thru that on my 87.

 

[black_demon69]

I would in your case replace hoses then gravity bleed for abit then close breeders have an assistant help with brake pedal for final bleed just don't release pedal with bleeder open.

 

[Mark_88]

Definitely sounds like a problem with either the lines or even the master. I would start, since you are having no success, by pulling the line on the master and pumping the pedal...if you get a good squirt from there, have someone hold the pedal in after the fluid shoots out (watch your eyes on this one and wear a face shield if possible) then plug in the line...go to the T for the fronts and do the same...and just follow the flow from the master.

Takes a bit more time and wastes a bit of fluid but it's the only way to track down where the fluid stops flowing. Do the same for the rear as needed...

Once you get the flow going to the caliper I'd suggest try using one of those one-man bleeder things...I've done all my bleeding (three different vehicles) with these $10 kits and they work great...just pump the pedal once after cracking the bleeder and watch the bubbles...

 

[ab_slack]

Definitely sounds like a problem with either the lines or even the master. I would start, since you are having no success, by pulling the line on the master and pumping the pedal...

I tend to put the probabilities with the rubber line so would start at bottom and then work up to master rather than master down.

Start at the end of the hard brake like at the junction between the had brake line and the rubber line. If it flows good there you know master and hard brake line are good.

If not, it is a good chance it is the rubber line as long as you don't have a problem at the brake caliper connection.

Essentially the same thing Mark suggested, just different direction.

 

[Andy D]

You have something sucking air. Where you see a leak is where I would start. 26 yr old brake parts that sat for 2 yrs are suspect. You are on a slippery slope.

The Rat came to me with a fully functional brake system. A line started leaking when I unclipped it from the frame to do some work. The bleeders were frozen, and the lines just crumbled in my hands.
.Everything inside of the front rotors to the Master cylinder is new up front. Out back only the rear hose is original. I have never replaced so much stuff on a brake system. The truck only sat for a yr

Last weekend, I just finished rigging a cable splice hookup thingy that I broke when replacing the right rear parking brake cable. I still need to tighten up the rear brakes.
The bad news is you will probably need a bunch of stuff before you are done. The more stuff you take care of before you put the truck to work.the better off you'll be. I have been dealing with rusty brake lines since forever. I drove the truck until the clutch failed 100%. Then I started fixing stuff The clutch was shot when I bought the truck. If handled gently , I could drive it. Gently enough to not panic stop. and blow a line. So I saved myself from that at least.