Brake bleeding trouble... still

[jaros44sr]

^^^^ i agree, like to see pics., glad you got the problem solved....wouldnt have suspected the wheel cylinder

[Stocker]

See my post #26... I still haven't figured out the whole pic thing. One of these days I need to work on that....

It's the truck in my avatar, with several more years of wear & tear on it.

[litew8]

Do you have any pics on the internet somewhere?
You can link to them by clicking the Insert Image button, then
copy paste the URL where your picture is.

[VWNate1]

Glad to hear of this .

FWIW , in these trucks , the original brake adjusting slot was on the outer face of the brake drum , you had to dismount the wheels to adjust the brakes , not a problem as this was only done during routine brake shoe relacement then the self adjusters did the rest .

For those who don't know , the self adjusting brakes are operated by backing up then stopping sharply ~ every time you replace the brake shoes you should also take the time to clean the threaded brake adjuste and lightly grease the threads with white lithium grease .

If the edges of the adjuster star are rounded , it's because the adjuster was too stiff to turn and self adjust ~ lucky for you , this is a cheap part available in any FLAPS .

What *I* do is : drive to a local steep hill , drive to the top then back down and brake hard to a complete stop several times , this will bring the most out of adjustment brakes right into spec. in 99 % of all vehicles .

I just received Motive pressure bleeder from JEGS and will try to get my big brother to come over and take photos of how it's used next week or whenever ~ it's dead simple and cheaper than paying the garage to do it once , plus you get to keep another tool and can make $ and freinds with it for the lext 10 years .

I hope all here know to never turn the brake drums ? .

[camrycurt]

Originally Posted by VWNate1

I hope all here know to never turn the brake drums ? .

Nate,

I wasn't aware that this wasn't recommended. Why is it a problem to have the drums turned? I thought that was a recommended part of a brake job.

Thanks!

[ole dollor]

Originally Posted by camrycurt

Nate,

I wasn't aware that this wasn't recommended. Why is it a problem to have the drums turned? I thought that was a recommended part of a brake job.

Thanks!

i done it all my life, as long as the drum is not to thin....i will say that nowadays that drums a lot cheeper than when i was doing this for a living, but i turned rotors and drums all the time....

[litew8]

Searched these forums and found a picture of Stocker's truck.
I would have grabbed more, but his photobucket account is locked

In this shot we can see the rear wheels that needed attention

[Stocker]

I'll be dipped!! Guess I completely forgot about that.... even forgot I ever had a photobucket account! Must have been from years ago when my daughter did that for me. Looks like most of the clearcoat was still there when that pic was taken. Now the truck looks like it has leprosy!

[VWNate1]

The why not , is because , even if the drum is still within spec. , it's too thin and will overheat & fade during towing or emergency stops .

I learned this when I took my Journeyman Bendix Factory Training , before then I too automatically turned all drums then I learned it's a B. S. sales gimmick to sell more drums .

What the Bendix Engineer said was : unless the drum is so severely out of round that you feel the brake pedal pulsate , or if it is so severely bell mouthed that the shoes wore un evenly to the side , the drum MUST NOT BE TURNED for basic safety reasons .

Sort of like changing the condenser every time you replace the points because " the condenser takes a ' burn ' to the points " ~ TOTAL BULL CRAP ! the only reasons to change condensers is failure (rare) or if the points are unevenly pitted ~ once in a while you'll get evenly pitted contact points and that condnser is -GOLD- NEVER replace it and your points will last 4 X longer .

But , you say ' what about when the shoes went metal to metal and the surface is all torn up ? ' ~ just sand it a bit with # 600 grit (coarse) sand paper and as long as the drum isn't over sized , run it ~ the new brake shoes will bed into the rough drum surface in 10 miles and be fine .

[slikside]

Originally Posted by VWNate1

The why not , is because , even if the drum is still within spec. , it's too thin and will overheat & fade during towing or emergency stops .

I learned this when I took my Journeyman Bendix Factory Training , before then I too automatically turned all drums then I learned it's a B. S. sales gimmick to sell more drums .

What the Bendix Engineer said was : unless the drum is so severely out of round that you feel the brake pedal pulsate , or if it is so severely bell mouthed that the shoes wore un evenly to the side , the drum MUST NOT BE TURNED for basic safety reasons .

Sort of like changing the condenser every time you replace the points because " the condenser takes a ' burn ' to the points " ~ TOTAL BULL CRAP ! the only reasons to change condensers is failure (rare) or if the points are unevenly pitted ~ once in a while you'll get evenly pitted contact points and that condnser is -GOLD- NEVER replace it and your points will last 4 X longer .

But , you say ' what about when the shoes went metal to metal and the surface is all torn up ? ' ~ just sand it a bit with # 600 grit (coarse) sand paper and as long as the drum isn't over sized , run it ~ the new brake shoes will bed into the rough drum surface in 10 miles and be fine .

Well, sounds logical enough......but too late. For me anyway. I don't think this is widely known (except here maybe). I too thought this was the right thing to do.

[VWNate1]

No worries ;

Few ever bother to take the time and effort to attend factory service , no matter who's it is ~ I take the job very seriously and always did so I'm still learning although my daily Mechanic's works is done .

[lsett]

Hello, this thread has been helpful trouble shooting but I could use some advice. I’ve got a 1966 GMC with a brake pedal that goes to the floor- no resistance. New master cylinder, proportioning valve and front brake lines. Disc in front, drums in rear. I have bled the **** out of these brakes and I have no pedal. Must be a leak somewhere, but no visible signs. I pulled the back wheel off thinking maybe it’s a bad wheel cylinder (after reading these posts). I don’t see leakage on the cylinder, but the inside of the drum is soaked. The trouble is that I can’t tell if it’s grease or brake fluid that has attracted dirt over time. The brake shoes themselves look ok wear wise. Question is- do I bite the bullet and try replacing the cylinders, shoes and hardware?

[AussieinNC]

Did you bench bleed the master cylinder?
Is the vehicle fitted with a booster?
Did you check the rod depth in master cylinder ?

How much fluid comes out of the bleed nipples when you bleed them?

What is the inside of the drum soaked with?

Clamp off the flex hose feeding the rear brakes and try bleeding again....

Might be bad wheel cylinders...or bad axle seals or both....

Can you pump up a pedal at all?

[lsett]

Originally Posted by AussieinNC

Did you bench bleed the master cylinder? Yes- several times

Is the vehicle fitted with a booster? Yes brand new

Did you check the rod depth in master cylinder ? No, but the MC came fitted to the booster, so I’m assuming it’s good

How much fluid comes out of the bleed nipples when you bleed them? A lot. It’s pretty consistent

What is the inside of the drum soaked with? It’s hard to tell. Some of it looks like grease, but I’m wondering if it’s just grime thatnwas picked up by leaking brake fluid. Weird thing is that the cylinder looks dry, however the little plate under it is soaked. Which could only be brake fluid.

Clamp off the flex hose feeding the rear brakes and try bleeding again....

Might be bad wheel cylinders...or bad axle seals or both....

Can you pump up a pedal at all? Nothing. It goes to the floor.

I’m going to do cylinder, pads and hardware. Everything is wet in there so I really should do it anyway. Keeping my fingers crossed that it works. It’s getting cold in CT and I want one more long ride before it snows!!

Posted via Mobile Device

[zicc1835]

subbed

[VWNate1]

THANK YOU for the photos .

Looking at the wheel cylinder it doesn't appear to be leaking but *gently* rolling back the bottom part of the rubber boot on each end will instantly tell you, either it'll be wet inside or not .

Certainly this needs to be taken apart cleaned and re assembled, riveted brake linings re better than bonded (glued) so depending on wear you -might- want to clean and re used them, new shoes are dirt cheap @ brakeshoewarehouse.com (? SP ?) or any FLAPS can get you those standard Bendix shoes in a day if they're not on the shelf .

Either way, get some white lithium grease and clean and lubricate the adjusters too, you'll be glad you did once it's all working again .

Remember : never, EVER turn in the old shoes (or any other parts) until two weeks after the job is done and you're 100 % satisfied as once you turn them in they're -gone- never to return, a problem when you take back the wrong new/relined shoes....

Resist the urge to have the drums machined/turned unless you had a pulsating brake pedal before you took it all apart .

Everything should be cleaned bone dry before re seemly, don't forget the dab of white lithium grease on the backing plate where the shoes touch ~ a tiny dab'll do ya there .

Only take apart ONE SIDE AT A TIME ~ this way when the job goes south or other problem crops up, you'll have a proper template of how to reassemble it all later .

Be smart and check under the lower edge of each cylinder's rubber boots, both ends, all four wheels .

Me, I'd at the very least take all four brakes apart for cleaning, inspection and lubricating as once one is dirty/greasy, they all are .

The front wheel bearings prolly need re packing too at this point .

You may not need much in the way of parts, just cleaning and so on .

[rpmerf]

I'd start with cleaning it down with brake clean, then attempt bleeding again. That way, if any NEW fluid shows up, you know it came from the wheel cylinder.

Some other brake bleeding tips. If you are leaving the bleeder open while pumping, wrap the threads in teflon tape to prevent sucking air from around the threads while the bleeder is open. The better method is to have one person open the bleeder, another press the pedal, close the bleeder, release the pedal. This can help prevent sucking air in from around the bleeder. The reason pressure bleeding works, is it is always pushing, never pulling, so it will not pull in air from around the bleeder (or anyplace that is leaking). Similarly for vacuum bleeding, but you can see bubbles in the vacuum line that are pulled form around the thread, or a bad seal between the vac hose and bleeder nipple. Vacuum bleeding will also pull air IN at any leaks in the system.

A couple issues. Bubbles down like moving downward. If you leave the bleeder open, the bubble can move forward and back without ever getting pushed out.

Never let the master run dry or you have to start over from square 1.

[Baime]

Originally Posted by PHAT TONY

I'd take the tape off the bleeders to start; they bottom out to seal. You need to keep the pin in the end of the prop valve from moving while bleeding; it may want to push out. If you have a vaccum pump they work great to suck fluid to the rear to start the process; I think you have air in the line to the back and its jerking you around going from side to side as you bleed. This has got me twice! I used a cheapy hand pump to draw fluid first to the passenger rear, then drivers (make sure system is sealed at the 3 other brakes). Once the line is free of air, and you're sure the prop valve stays centered, they'll bleed out quick.

My Blazer didn't have enough brake to stop the rear wheels in drive at idle on jack stands! Seems like I used 35 gallons of fluid and still had air in back; it took a while with the hand pump but I eventually got some BIG bubbles that must've been moving back and forth. I went through the SAME thing on a customers '68 GMC too.

Phat Tony,
Thanks for your comment on bleeding brakes. It helped me.

What I was observing after replacing the rear braking system:
- Pedal would go to the floor, and brake light would turn on.
- Pumping the brake a few times gave me working brakes, and the light would turn off (I'm assuming the piston inside that sensor would recenter once I got pressure on each side.)

What I was doing:
- Bleeding the brake system like crazy. Mostly in the back, but also at the master cylinder and the front calipers too.
- I was observing foamy air bubbles in the back. It seemed worse on the passenger side.

What I did:
I almost gave up, and drove it to a shop in town that I think is decent, but I tried your recommendation of using a vacuum pump to bleed the system.

I bled out a full cup of fluid from both rear cylinders at the bleeding nipples, and I had good brakes. What a relief.

I'm never going to bleed brakes again without using one of these vacuum pumps. I also really like that I don't have to get a second person involved to do this.

Thanks again,

JP

[VWNate1]

Vacuum bleeders are simple and easy to use .

So are pressure bleeders, I vastly prefer my Motion Pro pressure bleeder ~ it's also a one man job tool .

[guyryan100]

I found instructions on here somewhere for making a pressure bleeder using a garden pump sprayer, a hose fitting, and a rubber gasket. It made bleeding much easier, and got me past the never ending air bubble issue. It was about $25 in parts from the hardware store.

[VWNate1]

The main thing when pressure bleeding is to never use too much pressure .

I rarely go over about 5 PSI .

[Boog]

Yeah buddy! Too much pressure and not a good seal on the reservoir lid can make an awful mess. Do I need to remind anybody brake fluid can remove paint?