02flaresidesport

This time for the brakes, I have replaced the following, The brake booster, master cylinder and the brakes, bleed them and still it goes to the floor. And the guy who did my brakes and my brothers cant figure it out either, were on the 3rd master cylinder now and it just keeps getting worse. There are no vaccum leaks and it the booster has sucksion. Any ideas?

Fast Hampster

The pedal going to the floor doesn't have anything in common with vacuum leaks. This is usually caused by front brakes leak or by air in the system. I suppose that is can't be caused by all of master cylinders you've tryed. Is it possible that you still have some air in the lines?

02flaresidesport

we just bleed the again and cleaned the lines. No luck. Its starting to get annoying. We had a similar issue with the 81 dually.

Fast Hampster

I think that some additionsl info is needed, What caused you to replace all of those? And what did you mean by "brakes" in your first post? I'm just trying to figure out what's going on in your brake system right now - new master cylinder is assumed as "working", leaking booster would cause major idle decreasing with floored brake pedal. Parts we have left for checking: lines (assumed fine), wheel cylinders and frame-mounted ABS module (which might have some air in it, but i doubt it)

02flaresidesport

The reason for replacing, the master cylinder and booster was, the booster started leaking and since that didnt fix it, we replaced the master cylinder and brakes, because the brakes were getting close to needing replacement. So after all of that and bleeding the brakes the pedal still was right on the floor. It had been like that for a while 2-3 months, and I was driving it today, and I almost hit someone that slammed on there brakes in front of me. The pedal goes nearly all the way to the floor. So I took it in to have it looked at. And supposedly the brand new master cylinder is no good. So it was replaced, the lines were cleaned out and the brakes were bleed. Still no change, it actually got worse. So its possible that the master cylinder wasnt good to begin with. We have had this happen before. I am just trying to figure out what else it could be.

Fast Hampster

generally hydraulic system is not the place for any sort of miracles as long as it has no air bubbles inside and it's closed (i mean hermetic closed). Let's make it clear - your brake pedal starts to work only near to the floor, and it feels very soft, and the breaks are "weak", right? I think it points to front brakes failure. It's exactly the way it behaves when front brakes do not work at all. By the way - if you engage the parking brake and press the brake pedal - do you feel the "working height" difference? And one more question - if you fill up the brake fluid reservoir, and "work" the pedal for couple minutes (with engine off and running - test separately) - will the fluid level change? I'm afraid that "lines cleaning" might cause some issue also - it's my personal opinion, and not a recomendation at all, but i'm very careful and suspicious about any "cleaning".

02flaresidesport

I finally got it! I replaced the master cylinder again, and bleed the crap of them, I finally got it. I have brakes again! Now I gotta get new shocks.

Fast Hampster

Congrats about brakes!

my92

How many master cylinders did you go though, where did you get them and what brand?

Just call me Sean

iTrader: (1)

and did you bench bleed it first before installation?