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Used my old might vac we pulled fluid and air and it will not stop. Pedal still on floor. WE are sucking air from somewhere. How do you bleed a existing Master Cylinder 5 years old on car without a bleed screw on MC. This my next step, if this not clear the air i will remove caliper and split in half and hope it is the problem, but first MC Thanks for any help
Our cars have lip seal calipers. Unlike any other car. You can not successfully use a vacuum or suction bleeder on these cars.
A lip seal seals when being pushed against it. But does NOT seal under suction. (It's like a one way valve). So as you pull a vacuum, you just keep pulling air past the piston seals. Your basically just spinning your wheels. Or pissing up a rope.
You can reverse bleed, pressure bleed ,gravity bleed. The good old fashioned 2 man bleed. But a suction bleeder just isn't going to work.
Our cars have lip seal calipers. Unlike any other car. You can not successfully use a vacuum or suction bleeder on these cars.
A lip seal seals when being pushed against it. But does NOT seal under suction. (It's like a one way valve). So as you pull a vacuum, you just keep pulling air past the piston seals. Your basically just spinning your wheels. Or pissing up a rope.
You can reverse bleed, pressure bleed ,gravity bleed. The good old fashioned 2 man bleed. But a suction bleeder just isn't going to work.
Amen brother!
Act normal, get a motive bleeder. You've most likely tripped the porportioning valve and pumping the pedal and gravity bleeding will not work. You can try stabbing the brake pedal to bring that proportioning valve back around... but you've dug yourself in so deep.
Perhaps use the Motive Pressure Bleeder that you already have (and was already suggested in a similar thread)?
A C-Clamp, or a big grip-clamp, is all you need to seal the plate. Many of us (me included) only use the air pressure, and remove and refill the fluid only in the master cylinder.
This assumes, of course, that the master cylinder is already bled, and your proportioning valve is centered.
Every time I see the mention of the Motive Pressure Bleeder it reminds me of the issues I had trying to get it to work on my 2 Corvettes. I had to have two different master cylinder adapters to even put the part on the car. It leaked pressure above 15 psi and did not push the fluid out completely. It ended up making a mess and not being as useful as it sounded from the manufacturer.
I have used the inexpensive, little Mighty Vac to pull the fluid and it was unable to pull enough hard enough to get the air out of the system. Waste of money....
The same from Gravity Bleeding as all it did was drip all night long and in the morning the air was still there.
The last Brake Bleeding tool I bought has turned out to be my salvation regarding Corvette Brakes. I tried a Phoenix Reverse Bleeding System and it really does an awesome job bleeding air out. This little hand activated pump attaches to the bleeder screws and pushes fluid UP and the air goes OUT through the master cylinder. It takes very little effort and makes the job easier to do. With the older fluid returning to the master cylinder it is easy to clean it up with a "Turkey baster" pulling the excess brake fluid out of the master cylinder.
The Bleeder comes with a bottle that holds 10-12 ounces of fluid in it that acts like the reservoir for the Bleeder Pump. When the older fluid comes out of the master cylinder it will be a different color so it is easy to tell when you have nice clean new brake fluid in the system.
The Phoenix Bleeder is a great tool and every mechanic should have one available to them. Flushing the brakes is important and needs to be done regularly, this system makes it easy enough to do by yourself! My kit came with short tubes and they make bench bleeding the master cylinder even easier to do on the workbench. I bought my reverse Bleeder as part of a "kit" and it came with a bunch of different adapters.
Lastly, as you are bleeding your brakes I would recommend that you tap lightly on the sides of the calipers and the brass unions used in the brake system. Tapping helps release the extra air bubbles trapped inside the loop and gets them out. I use a light mallet or a dead blow mallet and tap lightly. "Tapping" on the calipers is especially important after rebuilding the calipers in the rear, I have been able to remove a lot of air from those two calipers after any caliper work.
I don't doubt that the Phoenix reverse bleeder is a great way to get air out of your calipers (and into your master cylinder), and is on my list of stuff to buy. It may even reset the proportioning valve, I'm not sure, I haven't tried. If so, that would make it the tool to use in all cases.
The OP already has a Motive Pressure Bleeder. It just needs to get used (with a clamp, not the trash chains it comes with).
100%, tap junctions and calipers with a wrench while bleeding, to dislodge air bubbles.
I use two C clamps on the master cylinder to keep it sealed. Believe Motive is only rated for 15 lbs. My pump bottle leaked out the handle. I put fittings on my adapter and hook it up to my air compressor at 10 PSI.
I top off the master cylinder with fluid. Clamp down the adapter. Bled the front and rear at the same time. Typically I'm counting as the fluid is flowing out the caliper. Disconnect compressor hose, remove clamps, refill.... repeat.
Even with a tripped proportioning valve/brake light you can bleed the system. You don't need the pirportioning valve lock tool.
Used my old might vac we pulled fluid and air and it will not stop. Pedal still on floor. WE are sucking air from somewhere. How do you bleed a existing Master Cylinder 5 years old on car without a bleed screw on MC. This my next step, if this not clear the air i will remove caliper and split in half and hope it is the problem, but first MC Thanks for any help
You can do it while mounted on the car by disconnecting the regular brake lines and screwing in stubby lines that loop back to the reservoir (ends under the fluid surfaces) - just like in the picture. Raise the rear of the car so the master tilts forward - when done in a vise, the same forward tilt is recommended. The forward end of the piston cylinder is a dead-end tunnel and an air bubble can certainly get trapped there so that no amount of bleeding removes it. Use the foot pedal to push fluid through the master's ports and release trapped air.
Hear is what i found why i could not bleed air and had stream . The rear passenger side had a leak that i did not see until it grew to a puddle. I thought i was loosing fluid on the drivers rear even though the bleeder screws were leaking.I removed the passenger side rear caliper today which is sleeved . I could not believe the orange colored fliid in the bores of that caliper. Why after bleeding this orange colored liquid was not bled off. My master cylinder is clear and when i bled this caliper the fluid was clear. Now i just have to clean the four stainless bores. Can the stainless sleeves be honed or just rough up with crocus cloth?
Can the stainless sleeves be honed or just rough up with crocus cloth?
NO, do not rough up the bores. There's no reason to hone unless you have scoring on the walls. New stainless sleeves are just about a mirror finish so if you were to hone, use a very fine stone that polishes rather than cuts. Unlike a cylinder bore that needs to hold oil in the honing grooves, these bore surfaces need excellent surface contact with the rubber seals. Scratches in the bores will also provide a pathway for environmental moisture to find its way inside.
Orange fluid sounds like rust in the system but it shouldn't affect the sleeves. I'd flush new fluid through the calipers until it runs clear.
Gezzz, guys I've repaired more brakes than I can remember.
what's this nonsense about a mirror finish bore?
a nice fine cross hatch should be excellent. And what I would strive for.
O ring or lip seal. A nice fine cross-hatch should be fine.
Gezzz, guys I've repaired more brakes than I can remember.
what's this nonsense about a mirror finish bore?
a nice fine cross hatch should be excellent. And what I would strive for.
O ring or lip seal. A nice fine cross-hatch should be fine.
Just relaying what newly installed sleeves look like.
What reason is there for any scratch pattern? A scratch is a pathway for water to work itself in and behind the seal and for brake fluid to work itself out. Scratches would also be abrasive to any seal in there. We're not talking chrome-moly rings on a cast iron cylinder bore where you need the scratches to retain oil. The smoother the bore the better seal it's going to create with the rubber.
They don't say to refinish the bores. They say to inspect for scratches (Step 9). They also call out specific bore tolerances.
The spec for O-ring finish is different for a static application than for dynamic. If you have the ability to get a mirror finish, go ahead! It's probably easier to get new calipers, though. The SS sleeve bores are polished before the sleeves are inserted into the calipers.
The Parker O-Ring book calls out the surface roughness finish.
[QUOTE=signify;1608895351]Used my old might vac we pulled fluid and air and it will not stop. Pedal still on floor. WE are sucking air from somewhere. How do you bleed a existing Master Cylinder 5 years old on car without a bleed screw on MC. This my next step, if this not clear the air i will remove caliper and split in half and hope it is the problem, but first MC Thanks for any help[/QUOT]
Here is how to bleed the MC while mounted on the car.
I haven't read all the comments here but do know getting air out of the system is a pain in the ***. I've got a MITYVAC that I've used on other cars but it just wouldn't work on my 81 so I tried the Phoenix reverse bleeder and it worked perfectly. I absolutely hate dealing with brake fluid,to me it's the equivalent of nuclear poison,with every drop you pay attention to everything,don't want to get it anywhere it will eat paint. The MITYVAC will pull vacuum from anywhere,mainly a loose threaded bore at the bleeder valve. I've gone so far as to wrap teflon tape around the threads of the bleeder valve to eliminate any vacuum leaks,the trick is to leave the hole clear👍
Still lost
