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Trouble bleeding brakes.

20K views 29 replies 15 participants last post by  Justoyz2 
#1 ·
Let me first say I've done many of complete brake jobs in my life including masters.
I've never had trouble bleeding brakes ever before. I used to wonder why so many people had trouble on all the car forums I belong to.

Well, I'm having trouble.

1983 El Camino with power brakes. Front Disc and Rear Drum

Just did a complete brake job.
New front calipers, rear cylinders, master cylinder, all 3 hoses and of course pads and shoes. Rotors and Drums were both turned.

I bench bled the new master using instructions that said "New and Improved Procedure" You just put plugs in the 2 ports and keep manually pumping with a dowel until no more bubbles appear in the reservoir.
That was a new one on me. In the past they always came with tubes that you clip onto the rim of the master and pump the fluid all the way through.
Anyway, I did it the new way and it worked the way they described.

After getting it back on the car, I was able to bleed the brakes normally. I got my wife to pump the brakes for me. I went all the way around 3 times.

I thought I got all the air out. It acted like it. All the brakes were working with the car up in the air.

Test drove and have a mushy pedal. It will stop the car, but they don't feel good at all and the car didn't stop without pushing pretty darn hard. It feels like the pedal is going all the way down when I do that.

I put the car back up in the air and used my vacuum bleeder. RR, LR, RF and LR. Pulled about 3 oz of fluid out of each one.

Still got the mushy pedal that feels like it goes all the way down.

Should I re-bleed the master or do I just have stubborn air trapped somewhere else?

Oh, I didn't change the proportioning valve. It's original and 30 years old. Should I replace that?
 
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#2 ·
No on the proportion valve,, wont cause a mushy pedal,, here is what i did to stop a two person job,, get yourself a motive power bleeder,, under 60.00 and they have improved the resivoir cap to prevent leaks,, it looks like a small garden spray pump,, the last brake job i did on a g body I used the Motive pump, bled the brakes myself and had a great pedal afterwards,, if you do the old pump method,, be sure to block the proportion valve needle in the open postion,, have someone pump the pedal and you will see "rod" come out under pressure,, many people including myself did not realize that you need to hold this rod in the open position or it will proportion the fluid going back to the rear wheels and make pedal pumping a pain,, i will try to find Motive link,, Matty man
 
#3 ·
It's probably not the proportioning valve causing the spongy pedal. It may be air in the system and the rears may not be fully adjusted. Replaced my master cylinder last fall using the New & Improved bench bleeding method and that worked okay for me. That was a first also for that method.
 
#5 ·
I'm going down to O'Reillys to get one of kits where I can bench bleed the master the standard way.

I'll do that and re-bleed the system and report back here how it comes out.

I'm thinking there is trapped air in the master.

I'm wondering if the "New Improved" method is really the "More Profit" method.

It's a Wagner rebuilt btw.
 
#6 ·
Since this ain't your first brake job, I d say rebleed the mc the way you (WE) know.

Their are several different brake bleeding tools on the market such as one that forces fluid up from the rear, which is supposed to be better at trapped air. But no use spending extra money on something you won't use often. Vacuum (mitivac) worked fine for me in past.

Proportioning valves tend to first leak when going bad, which is mainly caused by dirty fluid. Rear brakes not adjusted out can give a mushy pedal also, but I'll assume you know how to adjust them already. Hope the mc rebleed does the trick.
 
#7 ·
That's a yes on the rear brake adjusting. I've got them adjusted up to a slight drag. I even put new adjusters in. The teeth were worn a little on the old ones.

I just got back from O'Reillys with the bleeder kit and more fluid. It might be Thursday before I'm able to get it all done. Not sure I'll get a chance to work on the car tomorrow.

Btw, for interest sake here are the instructions that came with my Wagner m/c:

http://www.cardone.com/tech-help/br...ices/master-cylinder-bench-bleeding-procedure

It's from the Cardone site but it is word-for-word the same as the instructions packed with my Wagner.
 
#9 ·
I'd start back with a bench bleed with the mc still in the car. Have your wife pump the pedal up n HOLD it - loosen the break line on the mc slightly while your wife's foot pressure pushes out fluid or air + fluid out. Repeat until only fluid comes out. I know that's elementary but start over with the basics. You can "bleed" every connection until no air spits out as long as your wife don't let pressure off the pedal you won't introduce more air into your lines. Repeat repeat repeat. At least until your fluid coming out is clear.
I'm not a break guy but that pedal shoul be harder than Chinese arithmetic.
 
#10 ·
This may sound like a Stupid Question, but I thought I would ask. This happened to me when I added disc brakes on the front of my 1967. My question is::::: When you installed your Front Calipers did you install them with the Bleeders on the Calipers in the top position. If you installed your Calipers with the bleeders on the Bottom you will Never get all of the Air Out. Check your Calipers:dontknow:
 
#11 ·
I'll put it back on the bench. You are supposed to bench bleed them because the brake pedal doesn't push the plunger as far as using a dowel will.

And yes, my calipers are installed with the bleeders on top.
 
#13 ·
Motive Power Bleeder

I have a Motive bleeder I bought for my Vette and, works great. The problem is that the master cylinder for the Vette has a round cap. I looked at Motive's web site for an adapter and, they want as much for the adapter as I paid for the whole kit. I went to the pick and pull and got rectangular master cylinder cap off another g body and I am going to drill the top and put in a hose barb that will fit the hose from the Motive pressure tank. Hopefully, I can make it hold enough pressure to bleed the system. I'll let you know in a couple of weeks - when I get the truck back together.
 
#17 ·
I have a Motive bleeder I bought for my Vette and, works great. The problem is that the master cylinder for the Vette has a round cap. I looked at Motive's web site for an adapter and, they want as much for the adapter as I paid for the whole kit. I went to the pick and pull and got rectangular master cylinder cap off another g body and I am going to drill the top and put in a hose barb that will fit the hose from the Motive pressure tank. Hopefully, I can make it hold enough pressure to bleed the system. I'll let you know in a couple of weeks - when I get the truck back together.
I tried that, too. It didn't work. If it works for you, let us know.
 
#14 ·
Back on this project today.

I went to the auto parts store and picked up a master cylinder bleed kit so I could put the master back on the bench and bleed it the old conventional way.

Got the master back on the bench and have been bleeding it for an hour with the conventional method.

I cannot get the rearward (front brake) part of the reservoir to quit spewing tiny bubbles from the inside. I'm warn out from pumping. No bubbles at all from the front reservoir compartment. That appears to be bled just fine.

This does not sound normal to me. It seems that everytime I've done this in the past, the tiny bubbles would completely disappear. Sometimes that would take a good deal of pumping. But, I've pumped this one to death and it keeps doing it.

Bad Master?

Again, this is a Wagner re-built I got from RockAuto.

Advice will definitely be appreciated. I'm about ready to eat this one go to NAPA and get a new and not re-built one.
 
#16 ·
Got to be. I'm sure glad I took it back off to re-bleed the old conventional way. Thanks for that advice.

Napa has a new and not re-built one. I think I'll go over and get it in the morning. I don't know who makes them for Napa but I do believe they are quality conscious on the parts they sell.
Autozone has a new Fenco but I think I feel better getting the one from Napa.

Looks like I'll just take the loss on the rebuilt Wagner from RockAuto. I don't think it's worth the shipping back to try and get a refund. It was $20.79 plus $4.00 shipping.

If I had left the original one on, I guess I wouldn't be dealing with this. It was working fine. I just thought it would be good to replace it since it was 30 years old and I was replacing everything else. It's been chunked but I wouldn't have put it back on anyway.

NEW NAPA MASTER
 
#21 ·
Hey Steve,,,, the proportion valve has a valve inside hence the the name "proprotion" the needle moves by pressure,, more pressure more the inside valve moves to block the fluid to the rear brakes,,, if we did not have this valve the rear brakes would lock up ,,, so next time you have a chance have someone press on the brake pedal and watch the little tip come out of the valve,, I cant recall if it comes out on the foward side or aft side,, it does not pop out much but an old master wrench told me about after I had issues bleeding my G body brakes,, you pump the pedal up hard and hold,, what does the Proportion valve do?? It meters the fluid, reduces the pressure and volume so you dont get a good full flow of braked fluid to the rears,,, it is a pain to block it open with a clamp of sorts but it cured my crap-tack-u-lor pedal,,, so in short get a motive power bleeder and that resolves all of my brake bleding issues,, Matty man
 
#22 ·
I got my new master from Napa and it bench bled just fine. The bubbles quit completely after pumping on it awhile using the conventional method with the clip on hoses.
This master also came with just plugs and instructions to bleed it the "New Improved" way. The guy at Napa says nobody uses that method. No one likes it.

I ran out of time today to re-bleed the rest of the system again.

I did make this out of one of my old covers though. Used JB Weld. I don't think that fitting is going anywhere.

With the plastic reservoir I don't want to put much pressure on it. Probably no more than 10 psi.
What do y'all think?






 
#23 ·
Hello Roger,,, I like the thought process on the cap to pressurize the MC! If ya use it two things pop in my mind, or whats left of it,, the rubber gasket, you need to modify it as well,, or my guess is you will blow brake fluid everywhere,, and the compressed air from your compressor is full of moisture and brake fluid is hyperscopic (absorbs moisture) so to me you are defeating the purpose,, but you are on the right track IMO,, still if you plan on doing your own maintenance the Motive bleeder is the cats meow!! I dont know what that means but sounds good,,,,, Matty man
 
#24 ·
Yeah, maybe 5 psi is enough. I think some people say time and gravity will work with no pressure at all.

Oh and I did modify the rubber gasket.

 
#25 ·
Ok, finally got a chance to get back to this deal.

Got the new master back on the car and got my wife to help bleed all the wheels using the conventional pump-the-pedal method. Test drove and still a little mushy feel. So back up on the stands to bleed again.

I thought this time I would try pressure using that old plastic cap with the air fitting glued into it. It didn't work very well. I used 10 psi but that would puff up the plastic cap some and it would leak air around the rubber seal. It also made it seep fluid around the rubber bushings where the plastic reservoir goes into the aluminum housing. I bled the rear brakes but stopped there. It was just seeping too much so I took it off and got my wife to pump the brakes again to finish the job. Oh well, the fitting in the cap thing was just a fun little experiment but it doesn't work. With pressure causing seepage around the reservoir bushings, I don't even see how you could pressure bleed a master like this using any kind of device.

Test drove again it it's feels right now. Firm pedal, stops positive and straight and will lock them up no problem. Got them a little hot and they faded some and I could start to smell them. So, I over tested on that run. I let it cool down and drove normally and they feel great.

One thing that's a little different is that there is a little noise from the master when pushing the brake down firmly. Kind of a buzz type of vibrating noise. I think I've heard brakes do that on other cars but not on this one before.

Anyway the moral of the story is to not use plugs to bench bleed a master. Maybe it works but one thing for sure is that if you have a bad master out of the box like I did, you will know it when bench bleeding the conventional way but you won't bleeding with the plugs.

Lesson learned and I'm really grateful to you guys that have helped and shared this process with me.
 
#27 ·
Need a little help; I am bleeding the brakes on a '72 El Camino. I replaced the lines from the Proportion valve back. I bleed the MC, PV, the rear distribution block and the wheel fluid entry point. I have fluid getting to the rear wheel cylinders, but nothing from the bleeder valve. I have removed/drilled and replaced the valves. I tried the Harbor Freight bleeder system and even tried to get fluid to come thru the valve, by placing a small hose onto the nipple w/the open end submerge in fluid, and pressing the pedal, and still no fluid. What do you all think the issue is?
 
#28 ·
If you have fluid at the backing plate fitting but not the bleeders I would think the wheel cylinders are full of sludge.
 
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