Brake Bleeding Heartache

[oldelpasso]

Hey Guys,

I had a soft brake pedal that felt like it wanted to go to the floor. I decided to try and replace the dirty brake fluid. The truck is new to me so I need to inspect the shoes and pads as well. I started by removing most of the dirty fluid from the master cylinder, replacing it with clean fluid, and bleeding starting at the right rear wheel (drum). I noticed right away that my bleeder wouldn't hold steady pressure with the bleed screw closed. I tested the bleeder on all 3 other wheels, pumped it up to 10-12lbs, and it held steady like I would expect. I figured the bleed screw was bad, but after a quick replacement it still leaked down pretty quickly. I don't see any visible signs of leakage (yet).

My next stop will be to replace the wheel cylinder. I'm thinking that may have been the cause of my spongy pedal in the first place. I've also learned through web searches about the Automated Bleeding procedure using the ODB programmer, which is on it's way via Amazon.

Am I on the right path? Any other advice or tips will be appreciated.

-OldElPasso

 

[man-a-fre]

Very well could be I was having a low pedal problem and replaced rear wheel cylinders and it fixed mine on my 1994 k1500 I think the cups on one wheel cylinder would suck in air when you released the pedal,anyways it fixed mine by replacing the wheel cylinders now I have a great high pedal. The weird thing was neither wheel cylinder was leaking fluid and there was a reciept in glovebox from previous owner from autozone for the duralast wheel cylinders which I did not put duralast back on , the cups were very flimsy. I'd stay away from duralast wheel cylinders.I used raybestos professional grade wheel cylinders.

 

[oldelpasso]

Very well could be I was having a low pedal problem and replaced rear wheel cylinders and it fixed mine on my 1994 k1500 I think the cups on one wheel cylinder would suck in air when you released the pedal,anyways it fixed mine by replacing the wheel cylinders now I have a great high pedal. The weird thing was neither wheel cylinder was leaking fluid and there was a reciept in glovebox from previous owner from autozone for the duralast wheel cylinders which I did not put duralast back on , the cups were very flimsy.

Thanks! Good to know. I picked up a set of AC Delco wheel cylinders. One side note, I did try to bleed that wheel and got a little fluid, but mostly air. I could never get it to pull solid fluid. The ABS Autobleed is throwing me off a bit. I've seen guys say you can bleed each wheel the old manual way, but others say you need to do it with the computer.

 

[454cid]

...I noticed right away that my bleeder wouldn't hold steady pressure with the bleed screw closed. I tested the bleeder on all 3 other wheels, pumped it up to 10-12lbs, and it held steady like I would expect.

How are you gauging pressure? Are you using a pressure bleeder, or some sort of tool to bleed the brakes?

After struggling in the past with bleeding brakes, I've found that gravity bleeding works well for me. I've had mostly new components when doing it, Though.

I figured the bleed screw was bad, but after a quick replacement it still leaked down pretty quickly. I don't see any visible signs of leakage (yet).

Have you had the drum off? There's lots of area/dust in there that will hold fluid.

My next stop will be to replace the wheel cylinder. I'm thinking that may have been the cause of my spongy pedal in the first place. I've also learned through web searches about the Automated Bleeding procedure using the ODB programmer, which is on it's way via Amazon.

What did you buy? Not just anything will do the brake bleeding.... which is mostly for the ABS. Normal bleeding, is find for the lines/cylinders/calipers. If the ABS has air in it, you'll get air in the remainder of the system next time the ABS kicks in, I would assume. I've never messed with the ABS.

I would guess it's the wheel cylinder. I've got one original, and one that got replaced 10+years ago.

 

[oldelpasso]

How are you gauging pressure? Are you using a pressure bleeder, or some sort of tool to bleed the brakes?

After struggling in the past with bleeding brakes, I've found that gravity bleeding works well for me. I've had mostly new components when doing it, Though.



Have you had the drum off? There's lots of area/dust in there that will hold fluid.



What did you buy? Not just anything will do the brake bleeding.... which is mostly for the ABS. Normal bleeding, is find for the lines/cylinders/calipers. If the ABS has air in it, you'll get air in the remainder of the system next time the ABS kicks in, I would assume. I've never messed with the ABS.

I would guess it's the wheel cylinder. I've got one original, and one that got replaced 10+years ago.

I haven't had the drum off yet. I got tired of fooling with it yesterday and needed a break. I'm going to inspect further tonight with the wheel and drum off.

I'm using a Harbor Freight bleeder. I didn't try gravity bleeding because I figured if the bleeder won't hold pressure, there's a leak in the system, which would make sense considering the mushy pedal.

I bought the Foxwell NT630 Pro, which does ABS autobleed. It's the low-end of the tools, but I couldn't see shelling out several hundred dollars (or thousands) for something I might use twice.

I think you're spot-on with the new components. Thanks for the advice! I'll update the thread when I find the problem.

-OldElPasso

 

[oldelpasso]

I installed a new wheel cylinder pretty quickly, but still couldn't get the rear brakes to bleed. I got tired of messing with it so I limped the truck over to my local mechanic who said the master cylinder was bad, and the the booster had a vacuum leak. What I thought was going to be a quick fluid refresh turned into something quite a bit bigger (and pricier). Good times!

 

[06June1944]

How was that abs tool? Currently working on mine but need to pump the air out.

 

[oldelpasso]

How was that abs tool? Currently working on mine but need to pump the air out.

Unfortunately it wasn't compatible so I returned it (Amazon). I can't remember the exact error, but after messing with it for a few hours I gave up.

 

[Schurkey]

I had a soft brake pedal that felt like it wanted to go to the floor.

WHAT VEHICLE???

If this is a 1500-series pickup, you've probably got the terrible 254mm (10") leading/trailing shoe rear brakes. They're almost certainly WAY out of adjustment 'cause that's what they do.

Consider upgrading to 11.x Duo-Servo rear brakes, potentially via an axle change to a much-stronger 9.5" axle assembly. (Harder/more complex if this is a 2WD instead of 4WD.)

 

[Nad_Yvalhosert]

WHAT VEHICLE???

If this is a 1500-series pickup, you've probably got the terrible 254mm (10") leading/trailing shoe rear brakes. They're almost certainly WAY out of adjustment 'cause that's what they do.

Consider upgrading to 11.x Duo-Servo rear brakes, potentially via an axle change to a much-stronger 9.5" axle assembly. (Harder/more complex if this is a 2WD instead of 4WD.)

According to post 6 a master and booster were needed and the problem was resolved.
Until it was resurrected with a question about a tool, not the original issue...