That's not a stupid question.

You may have to open the front bleeders and hit the brake pedal a time or two.

Just as a note - if you do the "Pump the brakes" or a pressure bleeder, there's a tool to prevent that from happening - you remove the warning switch, and install something like (note: Just first hit when I Googled it.)

Of course, replace the switch when through bleeding.

That's one thing I like about gravity or vacuum bleeding; it doesn't trigger the proportioning valve.

RwP

 

I'll give it a try after the ibuprofen kicks in.

How the hell does a seasoned Dodge mechanic re-center those proportional valves? I question if the method HY described to re-center them is reliable.

And one more thing. Why not just replace both the master cylinder AND the proportioning valve? It's not like it will break the bank. I came close to doing that anyway when you suggested it early in this project.

 

The only time I have ever replaced a proportioning valve, was when a customer moved to significantly better brakes on the rear of his hotrod, and we installed an adjustable one. I don't recall ever seeing one that failed.

The method I use to re-center them has always worked for me. Of course, it assumes that there isn't a buncha air in the front lines. Might try bleeding the fronts first, see if anything interesting happens.

 

UPDATE:

I gravity bled the front brakes according to Ralph's instructions. Both rears closed, both fronts opened. Had to pump the brakes a few times like Ralph thought. That got the drip going on both sides (LH/RH). About a drip a second give or take, the left a little faster than the right. Kept dripping about 15 - 20 minutes. Satisfied, I closed them off. Then I went back to the back brakes. Opened the backs up again (with the fronts closed). But this time (unlike what I did earlier today), I pumped the brakes a few times like Ralph suggested to get her going. She did. Both sides (LH/RH) dripped but the RH side stopped. The LH kept going and eventually ramped up to 2 drips/second. Healthiest wheel of the four. The RH wouldn't drip unless I goosed the brake pedal a little but then it would stop again. So went about 15 minutes with the LH dripping away. Satisfied, I closed the LH and got the RH fired up again. A fairly healthy drip. Let it go about 15 minutes. Got in the truck to push the brake pedal to feel it. Felt more robust. But for some reason the RH drip stopped after I pushed the brake a couple times. Whatever. I closed it off and packing it in for the night.

So if that proportional valve was knocked over, then HY's method worked!

But now, what should I be doing now?? Is gravity bleeding a full fledged way to bleed brakes? Or do I need to throw the pneumatic bleeder on it again? Or do the traditional 2-person bleed method?

Advise. Thanks Fellers!

 

Pump up the pedal, and see how it feels. If it's firm, then you are likely done bleeding. If it's spongy though, time to do some more. I have found that gravity bleeding won't always (rarely) get all the air out of the lines. The air collects in the high points, and stays there. When I think I am close, I use the two bodies method, with a twist..... Have warm body in the seat pump up the brakes (all bleeders closed) and HOLD pressure, and then start at right rear, and crack the bleeder open. You will get a nice squirt of fluid, and after doing it a couple times, it will shock the air loose, and pump it out. I usually go all the way around twice with this method, and I get a solid pedal. (after adjusting the rears as well. )

Just as a side note, rear brake adjustment is the biggest determiner of pedal height where the brakes start to grab. If you get a lot of travel before it firms up, adjust the rears.

 

Makes total sense. I do have a couple roller coaster spots that I suspect would be holding air...especially getting around the rear diff. I'll throw the wheels back on in the morning and do a crawl around the neighborhood and see how it feels. I'll be prepared to adjust those rear brakes and/or the HOLD/squirt method to knock out air gaps. Good tip!

Another question: When gravity bleeding, how long should you let the thing sit and drip, drip, drip, drip until the job is done? I let her drip about 15 minutes.

And another question: Why does gravity bleeding succeed when pneumatic and/or two-person method does not...too much air for the faster methods? I was starting with the fluid drained out of the system so it was all air by the time I got around to bleeding.

 

Gravity bleeding takes patience. And it will have fits with the roller coaster lumps at time, yes. (It's really fun when I do the uphill brakes on the Dakota in my 15* slope driveway ... or is it 25*? )

Pneumatic bleeder kits do have the reservoir re-filler; if you can get just that, and have the time, that's probably best to use with gravity bleeding for a good "charge the lines".

It's just that, as HeyYou said, there can be air bubbles still.

(Aside: If replumbing complete, make DAMN sure that the master cylinder is the HIGHEST point. I've seen lines run over the top of the MC ... ayep, there be air bubbles that Just Will NOT Go Away! on those vehicles.)

RwP

 

I usually only gravity bleed until it starts dripping fluid. (the lines are essentially full) then finish bleeding. I have used the two person method, a pressure bleeder, a vacuum bleeder, and the 'one man' bleeder valves. So far, for me, the two person method has worked the best. (plus, it gives me an excuse to drag the wife, or one of the kids/grandkids out to the garage. I get lonely out there. )

I gave up trying to understand the fluid dynamics of brake bleeding a long time ago. I just know what to do when things aren't going as I think they should. WHY they are like that, is STILL a mystery to me.

 

That pneumatic bleeder is worth buying for the refill bottle alone…seriously. That filter and filter holder at the exhaust blew out and shattered on mine. I had my compressor regulated down to 90 psi too.

One advantage to working on a hill is if you have to pee you don’t have to worry about laying in it.

 

I spent a lot of time working with hydraulics people who said the same thing.