Brake pedal soft only with engine running

[TylerZ281500]

your just bleeding one cylinder? i do right rear first 5 pumps and hold the 5th, then do it two more times at the same one, then do the left rear and do the same thing, then the right front same thing, left front same thing. byt that time the exta pumps are overkill but if your system is working right it should be perfectly bled.

are the bleeder screws on top of the the calipers, and cylinders?

 

[twomanymontes]

It does sound like you have air trapped in the ABS unit. There should be bleeders on the ABS unit as well. If not, have someone hold the brake pedal down, try to crack the lines loose at the ABS and see if fluid or air comes out. And as previously mentioned, make sure your rear brakes are adjusted properly, too much movement between the shoes and drums won't allow the system to properly push the air out. It's the differance between stepping on a brick or a sponge.

Good Luck

 

[TylerZ281500]

definitely a two person job. i bought a slef bleeder from eastwood once hated it tried a harbor freight unit liked it more but still hated it.

 

[duanes7]

Just tried a new booster and another master cylinder. No joy. The consensus is air in the abs or flex lines.

What would it take to just remove the abs altogether?

 

[TylerZ281500]

alot more for a 97, just more to delete but basically find the hardlines that go to front and rear and mark then, those lines have to go to the bottom of the proportion valve. dont know on a 97 but there might be sensors in that one so swapping to an older style valve might be necessary. otherwise once those hardlines are put back into the prop valve the rest can be taken off, ziptied away etc.

 

[duanes7]

The bleeders are at the bottom of the calipers and at the top above the hard line on the wheel cylinders. OK, I've bled these brakes about 9 times now and the pedal is still soft with the engine on. I'm pretty mechanically savvy and have always done my own work, but these brakes are starting to make me doubt whether I can get then right or not. The last time I worked on drum brakes was in 86-87. I'm pretty sure I have them right and adjusted pretty close. I even have installed a threaded bench bleeder plug into the master cylinder rear line port and still can't get the pedal pressure to firm up when the engine is on.

I'm afraid if I take it to a brake shop that they are just going to charge for some bs and then tell me the abs is bad.

If I pull the 60A fuse and disable the abs it should act just like a straight line, right? I did this and the abs light still goes out. I thought it should stay on...

 

[TylerZ281500]

the bleeders need to be on the top of the calipers, theres your problem right there.

and no to the abs, i dont think thats so. your abs is probably just bad and not unctioning right so i wouldnt bother trying to say its that. your brakes will still be able to be bled with an not so great functioning abs system. jack the front of your truck back up and switch calipers on each side, bleeder needs to be on top so air can get out, now that uve bled theses on the bottom any air has traveled to each wheel and just made a mess so extensive bleeding will need to be done once you properly have the bleeder screw on top.

 

[twomanymontes]

The bleeders are at the bottom of the calipers

The calipers are mounted on the wrong sides. Air is still trapped in the caliper piston cavity. Swap them side to side and rebleed.

By passing the ABS unit is not easy. Either way, if the ABS isn't funtioning, then the standard hydraulic brakes work the same way.

 

[TylerZ281500]

The calipers are mounted on the wrong sides. Air is still trapped in the caliper piston cavity. Swap them side to side and rebleed.

By passing the ABS unit is not easy. Either way, if the ABS isn't funtioning, then the standard hydraulic brakes work the same way.

this is what i was trying to say, just couldnt word it right.

 

[duanes7]

Well, duh. Don't I feel stupid. Will go out right now and swap the calipers.

And I've had this looked at by the dealership and their certified tech didn't notice this. Or at least didn't say anything...