Squirlye Posted September 1 Share Posted September 1 It's been awhile since I've posted, but I've kept an eye on the forum the best I could. I still have a ton of work to go on this truck. Slow going, but i have been using it as my daily driver for a while now. So now for my problem. The brake pedal will almost go to the floor when stopping. The weird thing is, when down shifting the pedal becomes firmer with the higher rpm's. Then fade when I'm at a complete stop. At first I just thought I just needed the brakes to be bled. So I had the wife help out. The fluid was definitely bad, it was very dirty almost black. She did the best she could, the brake pedal was still a little softer than I'd like. A couple days later the pedal was really soft again. When you start it up, if you have pressure on the pedal it will go almost to the floor. I'm not leaking brake fluid anywhere. Any ideas or suggestions? Link to comment Share on other sites More sharing options...
viven44 Posted September 1 Share Posted September 1 Sounds like air in the line (at least part of the problem) .... and I understand you have tried bleeding it. Do all 4 wheels gravity bleed well ? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted September 1 Share Posted September 1 Sounds like fluid is bypassing the master cylinder piston and returning to the reservoir. O-rings eventually give up, especially with sludgy fluid. You have a firm pedal, when you have little vacuum. Do you hear a hissing sound from up under the dash when you apply the brakes? Link to comment Share on other sites More sharing options...
mat in tn Posted September 1 Share Posted September 1 Sounds like fluid is bypassing the master cylinder piston and returning to the reservoir. O-rings eventually give up, especially with sludgy fluid. You have a firm pedal, when you have little vacuum. Do you hear a hissing sound from up under the dash when you apply the brakes? that really sounds like a failing master cylinder Link to comment Share on other sites More sharing options...
Rockhauler Posted September 1 Share Posted September 1 I'm just in the process of going through my truck from rebuilding it many years ago. Part of that is checking my brake components as the brake fluid was dark and nasty looking. Took wheel cylinders apart found both had one of the pistons seized and lots of gunk. Then figure lets see what the master cylinder looks like it had lots of gunk around the piston/spring and seals. The bore didn't look good either so I just replaced the calipers, master cylinder and the wheel cylinders as I like good brakes and yes all new brake fluid. I would expect your brake system might be the same if it hasn't been touched in many years. Since mine were still sitting on the bench here's what they looked like, Link to comment Share on other sites More sharing options...
mat in tn Posted September 2 Share Posted September 2 I'm just in the process of going through my truck from rebuilding it many years ago. Part of that is checking my brake components as the brake fluid was dark and nasty looking. Took wheel cylinders apart found both had one of the pistons seized and lots of gunk. Then figure lets see what the master cylinder looks like it had lots of gunk around the piston/spring and seals. The bore didn't look good either so I just replaced the calipers, master cylinder and the wheel cylinders as I like good brakes and yes all new brake fluid. I would expect your brake system might be the same if it hasn't been touched in many years. Since mine were still sitting on the bench here's what they looked like, I'm convinced that nobody flushes their brake hydraulics as often as necessary. not even myself. but yes, it should be done annually. otherwise, the moisture absorbed by the fluid rusts out the system from the inside out. Link to comment Share on other sites More sharing options...
Rockhauler Posted September 2 Share Posted September 2 I'm convinced that nobody flushes their brake hydraulics as often as necessary. not even myself. but yes, it should be done annually. otherwise, the moisture absorbed by the fluid rusts out the system from the inside out. Yes brake fluid absorbs moisture from the air so flushing would be a wise idea. Likewise I believe few people flush the brake system unless the brakes give trouble, me included. Personally every master or wheel cylinder I've ever taken apart the majority of the damage to the bore has been in the bottom. I doubt flushing would remove much of this gunk accumulation since bleeding draws from the top of the bore. It would be interesting to see how much gunk remains in the bores after flushing if one was to pull the pistons. I just tend to replace the brake fluid, hoses, calipers, wheel cylinders and master cylinder about every 10 years. Link to comment Share on other sites More sharing options...
mat in tn Posted September 2 Share Posted September 2 Yes brake fluid absorbs moisture from the air so flushing would be a wise idea. Likewise I believe few people flush the brake system unless the brakes give trouble, me included. Personally every master or wheel cylinder I've ever taken apart the majority of the damage to the bore has been in the bottom. I doubt flushing would remove much of this gunk accumulation since bleeding draws from the top of the bore. It would be interesting to see how much gunk remains in the bores after flushing if one was to pull the pistons. I just tend to replace the brake fluid, hoses, calipers, wheel cylinders and master cylinder about every 10 years. and how many people even keep a car that long anymore? I know I'm an oddball, i bought my first truck in 1991 and I'm still driving it. gotta go, I got brakes to bleed! Link to comment Share on other sites More sharing options...
85lebaront2 Posted September 2 Share Posted September 2 and how many people even keep a car that long anymore? I know I'm an oddball, i bought my first truck in 1991 and I'm still driving it. gotta go, I got brakes to bleed! Mat, I bought Darth April 1994 and have owned him ever since. I kept my Shelby for 11 years and only sold it because I had three kids and needed the money. Link to comment Share on other sites More sharing options...
mat in tn Posted September 2 Share Posted September 2 Mat, I bought Darth April 1994 and have owned him ever since. I kept my Shelby for 11 years and only sold it because I had three kids and needed the money. kids!!!! Link to comment Share on other sites More sharing options...
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