Hillbilly Silverado

iTrader: (1)

So awhile ago I ended up replacing all my brake lines with Stainless steel ones and putting on brand new calipers, rotors, and pads all around on my 99. Bled the truck the best I could and figured the ABS had air in it since the pedal would still go to the floor afterwards.

Let it sit for a bit because I couldn't get it on the trailer and have my old man haul it down to the dealership.

Fast forward to today, suddenly half my master cylinder was empty, no leaks or anything triple checked. Before the truck had no brakes driving it around the shop, you would hit the pedal and it would go to the floor and the brakes wouldn't work.

We bled all 4 corners again and topped the cylinder off. Drove it up and down the dirt road and you could lock the *** end up. Locked it up and had the ABS cycling and kept bleeding.

Eventually the pedal had some resistance right before it hit the floor and you could feel the ABS kicking in by the pedal pulsing up and down. We both ripped around and then I'd pull it in and bled it with a vacuum bleeder.

Now the brakes work good enough for me to drive the truck around on the dirt road and reliably stop it but still not good. The pedal still almost goes to the floor and the front wheels never locked up.

What has us really both confused is the fact when the truck is off, I can bleed the brakes so well that the pedal barely moves but as soon as the truck starts it about goes to the floor. I removed the ABS fuse before my last bleed to see if it would change anything and helped to restore a very small amount of the pedal but still nothing good and the fact from us ripping around getting the ABS to cycle that the fronts never locked up.

Is this normal if there is air in the ABS? Neither of us have had to do an ABS system that was basically empty. The master cylinder went dry during the brake line install and the ABS had to be removed due to the extreme rust of the old lines to even get the lines off the ABS.

I was thinking of throwing the truck in 4WD, putting the fuse back, and trying to cycle the ABS again instead of just 2WD. Almost just debating on deleting the ABS because I do not have the time to get it down to the dealership for them to use the Tech2 unless I can get the brakes working better where I don't need to trailer it. In all honesty I would like to have the ABS functional and working as it should but if I deleted it, it wouldn't bother me one bit. I really need my truck back on the my road soon with winter coming and work just won't allow me or my old man to take a day off to get it down to the dealership.

Thanks,
Mike

terravast4

iTrader: (25)

did you re-bleed the master cylinder after you ran it dry?

arthursc2

iTrader: (5)

I think the only way to do this is to cycle the ABS. Shops other than the dealer can do it. Firestone did mine for $100, in about 2hrs. I supplied the fluid because I am **** like that.

Hillbilly Silverado

iTrader: (1)

Absolutely. And the master cylinder is fine. No fading pedal and if you pump it up and hold, the pedal will stay where it's at regardless if the truck is running or off. The biggest thing is I can get this super firm pedal with the truck not running and I can barely budge it, then when I turn the key and start the engine, the pedal goes almost to the floor.

That's why I'm not sure if there's air in the ABS or not. It's such an odd symptom and I can't find anyone or anywhere that mentions this being an issue or even related to the ABS and it's the only thing I can think of it being related too.

Can't get it down and not paying to have it towed.

I am too, if I ever take my cars or trucks somewhere for any type of service I don't want to do, I always provide pretty much everything. Saves a lot between mark ups and stuff and I know what they used.

MikeGyver

iTrader: (5)

More details might help: rear discs or drums, Hydraboost or vacuum booster?

Hillbilly Silverado

iTrader: (1)

Disks all around. 99 NBS. Vacuum booster.

I think the master cylinder is bad.

This morning before work I unplugged the brake booster vacuum line and ran the truck, the pedal seemed to travel like it should, and the brakes seem to work. Later I'm going to unplug it again and do some 20-30 mph rolls on my dirt road and see how the braking is with it unplugged being it seemed to travel as it should.

I also checked the booster vacuum check valve and checked for leaks and no issues. So I'm heavily thinking it has to be a bad master cylinder that is leaking/not sealing when vacuum is applied. Not losing any fluid though so I assume it must be in the bore.

terravast4

iTrader: (25)

I just recently installed new discs up front and rebuilt the rears. I had all four corners open. it took a lot of bleeding to get the pedal firm. i tried to purge as much of the old fluid as possible since it was really old. the more fresh fluid i got in there the better it felt. i saved the old fluid in a water bottle and it was dark like used oil. i filled up two 16 oz water bottles and part of another but the pressure came back

MikeGyver

iTrader: (5)

Weird. Doesn't make sense. Weird.

MikeGyver

iTrader: (5)

Would crossed lines at the ABS unit cause this?

Hillbilly Silverado

iTrader: (1)

I followed a diagram on the ABS routing and did one line at a time when I did it. Plus the prebent stainless brake line kit I used had the lines labeled on each end for what line was what. I tripled checked the diagram I used was correct too. Plus I think if the ABS unit had lines changed around the brakes wouldn't work at all then.

And it wouldn't explain why the brakes work like normal when I disconnect the brake booster vacuum line. Only thing I can think of is a seal is leaking under vacuum at this point. It is the original master cylinder on a 179k truck plus the cylinder sat empty for a few weeks till I managed to tow my truck to the shop to work on it easier and replace the lines.

I'll be replacing the master cylinder at some point over my holiday weekend and I'll see if there is any improvement after I bleed the system again.