2nd Gen Non-Engine/Transmission More brake bleed problems!! Was supposed to be halfway to FL by now!

[CharlieFoxtrot]

96 2500 2wd, 4w ABS.

All I did was put in new front pads and one front hose last night. I had the bleed screws open when I retracted the caliper pistons. Brakes worked fine before this. All brake parts have 50K or less on them - new (not rebuilt) MC, calipers, wheel cylinders, hoses. (reason for new hose yesterday is it had rubbed on something). My ABS pump has the usual problem of dumping all pressure under hard stop, so I run with fuse pulled and have no problem.

I bled the brakes manually but they were very mushy unless pumped up a couple times. Pedal would go to floor under sustained pressure, although I think they probably did that before too. Technically I probably could have driven with them, but I wanted it to be right. Bled with a vacuum bleeder. Gravity bled a little too. MC level never dropped more than ~1/2" before refilling. I put the ABS fuse back in and cycled the ABS a bunch of times, like 20 or so. Pulled the ABS fuse and bled with the vacuum bleeder again. Started truck, pumped several times, had virtually no pedal at all!

Waiting for my bro-in-law to arrive so we can manually bleed again. Any more suggestions? I'm in Katy TX at the moment, but need to get on the road to FL and then to NY ASAP. If I had time and money, I'd buy the rebuilt ABS pump and have it bled at the dealer to rule that out as a problem, though the brakes worked fine with the fuse pulled before.

HELP please!

thanks
kevin

 

[petersonj]

96 2500 2wd, 4w ABS.

1. All I did was put in new front pads and one front hose last night. I had the bleed screws open when I retracted the caliper pistons. Brakes worked fine before this.

2. I bled the brakes manually but they were very mushy unless pumped up a couple times. Pedal would go to floor under sustained pressure, although I think they probably did that before too.

There seems to be a conflict here. If I understand this correctly, you are saying that you think the pedal goes all the way to the under sustained pressure before you ever started this brake job. If this is the case, then there is a problem that needs to be resolved before you bleed the brakes.


- John

 

[seafish]

Did you bench bleed the new MC before installing it??

 

[CharlieFoxtrot]

I bench bled the new mc and i just replaced it again and bench bled.

After bleeding extensively the pedal has some resistance. But leave it sit for a minute and it loses all resistance. It pumps up with a couple of pushes but goes dead after a minute again.

I was blaming some misbehavior on the failed ABS but i have the fuse out and i dont know if it can be a current cause.

Stumped.

 

[CharlieFoxtrot]

There seems to be a conflict here.

Yes, I should say I had brakes with poor feel but good performance, other than the failed ABS, until this pad change. And if the MC was suspect, replacing it should have fixed the problem.

I could put the ABS fuse back in and try working air out of it again but I seem to have a bigger problem than air in the ABS. Or if this is an ABS problem, it's worse than anyone I've seen posting about it. Next step may be trying to plumb around it.

I don't have time for this.

 

[seafish]

Hate to say it, but it certainly is possible that the MC is bad right out of the box if you are using an aftermarket and imported rebuild MC.

 

[CharlieFoxtrot]

It's a new MC. Not rebuilt. But it is aftermarket, and since nothing is made in the USA anymore, it's probably imported. Getting another in the morning.

 

[CharlieFoxtrot]

I know someone posted a source for rebuilt ABS hydraulic units, and I saved it on my other computer. In Florida. Where I can't get to until I have brakes. I'm searching the forum but haven't found it so far. Anyone know it?

Thanks!

kevin

 

[Nigel]

When you changed the calipers the last time did you mix them up? I know of two instances recently where the calipers were in the wrong box and the owners couldn't get the air out. The bleeders should be at the top.

Nigel

 

[CharlieFoxtrot]

Calipers are right side up. This is all the same parts that have provided acceptable braking for the last 50k miles, except the pads and a hose. What happened?????

 

[Tuesdak]

Bleeding a MC is no fun and takes time and lots of fluid. New bad ones are a nightmare... Hopefully it's the correct part and also not a knock off.

Is it loosing fluid? Only thing I would triple check is the rear cylinders didn't blow out under the pressure of a new MC or other leaks including leaking into the boot of the new caliper. New parts don't mean good parts. The rears being way out of adjustment or stuck proportioning valve comes to mind as not helping with the process.

 

[B.G. Smith]

Hopefully you are out of the woods by now. If not, you may need to bleed the rear brakes and make sure they are adjusted up pretty close. If the fluid got low when you were bleedin with the vac. air may also be in the rear. bg

 

[CharlieFoxtrot]

Thanks everyone!! I bled each fitting from the MC outlets thru the ABS outlets. Found a bunch of air in the combination valve and got back to my normal crappy pedal.


I'll keep working with your suggestions to get a decent pedal when I have time, but for now at least I can go home!!
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