Ive been trying for the last few days to get the brakes to bleed on my 89 pickup. It all started after installing an Aussie Locker in the rear, the axles had to be removed, so the wheel cylinders had to be disconnected. After reassembling everything, the rear brakes would not bleed. I am at the point now where I bypassed the lspv. When I try to bleed them I get mostly air with a little bit of fluid. I have gone through about a gallon of brake fluid and still have no pedal. It is not leaking fluid anywhere and the fronts bleed fine. The master seems good, it pumps fluid, I dissasembled it and all seals are good. It has to be pulling air from somwhere. I have been gravity bleeding it, vacuum bleeding it, pump and hold bleeding it. I am stumped. Any ideas?

 

Having someone help you with the pump/hold method? And starting pass rear, then drivers rear, then pass front, then drivers front?!

 

I have a helper, and I am bleeding in the correct order. The brakes were fine before I did the locker.

 

well it is possible that your master has gone out. I have seen stranger things happen before. My TPS went out on my 4runner, and all I did was a HG.

 

Hmmm. Nothing is preventing the fluid from flowing? As in the bleeder valves aren't clogged(very tiny opening on one end). Or nothing left of whatever you used to plug the lines while they were disconnected still in the lines? Are the wheel cylinders filling with fluid? They'd have to be full before you'd get ANY fluid to bleed out, right? Even if it was mostly air, air wouldn't be able to push fluid out the bleeder unless the thing was full of fluid. No? Just trying to figure out how you're getting mostly air, instead of mostly fluid. That's very unusual. Both wheel cylinders letting air in before the bleeder valves would be equally baffling.

Odd.

 

Did you let you resevoir go totaly dry?

 

Nothing is cloging the lines, when it does get the occasional straight fluid it flows just fine. the rear brake do work somewhat, but not enough to lock them up (even without a prop. valve). I do not think the master is bad, if it is it would not prevent me from bleeding the brakes, I would just have a soft pedal.

 

Did you let the resevoir go totaly dry?yes or no?

 

It did go dry, but I bench bled the master before trying to bleed the system.

 

had the same problem. pull the drums of the rears and take out the rear break cylenders, peal of the rubber boots on eather ends if they are filled with fluid when your takeing them off the cylenders are trash(fluid was getting pased the pistons). for some reason my breaks were fine untill i disconected the lines and reconected them i must have bleed a gallon of fluid out untill i discovered this. after i replaced the cylenders in the rear it took me 5minutes to bleed with the two person method. she locked up great after that

 

Yeah i was gona suggest bench bleeding the MC sounds like your doing it right. I always bleed the little distributor box that splits into the rear brakes. I do the passenger rear, then the driver rear then the passenger front, then the driver front, then go all around again. Are you bleeding them with the cap ajar on the resevoir so it can flow and doesn't just create suction? Did you do something to the booster push rod?I get my helper to go pump pump pump hold then i open the bleeder screw. When you pump the peddle with all the bleeder screws closed does the pedal get firm?good chance its the wheel cylinder^^^^^^^^^^^^^

 

undo the brake line at the Tee where it gos to both rear wheels and have your helper give it a good pump and see what kind of pressure you have.
if it is good there then look at both rear cylinders on my buddy's truck we went through 3 bottles of fluid and it still had bad pressure we replace both rear cylinders and it was fixed I took one apart to see what was going on and it was full of gunk and sediment.

 

I just tried what CyMon suggested, and I get good pressure coming out of the line. When I try and pump up the pedal with all bleeder valves closed, it does build up some pressure, but if you let it sit for a few seconds, I lose the pedal again. I am bleeding with the cap off, and I did not mess with the push rod.

 

Replaced the wheel cylinders, problem solved. Thanks for the help.

 

good to hear you got it fixed did you take one apart to see what was in it

 

I did take them apart, the drivers side was not that bad, just a little dirt, the other side was full of crud and the seal on the piston was broken.

 

I thought it would be weird to be both wheel cylinders at the same time. But, either way replacing them both isn't real spendy. I keep a pair that I've rebuilt for spares. I would recommend doing the same with your old ones, they've come in handy on at least one occasion so far for me.

 

Well, Im back to having the same issue, the brakes worked good for a few days, and now I am back to having my original problem. Any other ideas. This is getting rediculous.

 

when you bleed the system did you place a block of wood behind the pedal ?

you may want to check your MC at this point either replace it or rebuild it I would also reconnect your lspv.

brakes can be a very frustrating endeavor.

also how many miles on the truck and has the MC been replaced before ?

 

I'm having the exact same problem. Bought my truck 3 months ago. MC was bad when I bought it. Changed it out, bled brakes, pedal much better. Everything was great. Then 3 days ago, pedal went soft and would go almost to the floor before any stopping power.

So I changed the MC again. And tried to bleed the brakes. Now I can't get any fluid to the rear! After reading these posts I now know that I'm bleeding in the wrong order. But would the order really cause no fluid to come to the back brakes????