Seems simple enough but its giving me a hard time (No brake pressure)

[OneJArpus]

OK.

I have purchased a reman brake master cylinder (abs). I bench belt it on that car, hooked up the fittings, put the lines into the res, pumped it a bunch of time til there was NO air in the system.

I hook up the lines, i go to the RR tire hook up my mighty vac and i sit there for 40+ minutes with no fluid coming out. Just a ton of air. So, i suspect a hold in the line some place.

I disconnect the exit lines on the ABS pump hook up the bench bleeders there, put the other end into the bottle and pump the brakes again to see what the pressure looks like.

As long as the front brake line isn't connected the brake pedal will travel the entire length. You can see the fluid come out of the front brake lines no problem. But you see fluid & air come out of the line for the rear brakes, but instead of pushing the fluid forward, and then the fluid in the res going down it seems to just push the same fluid back and forth and it sucks fluid from the bottle with the bleeder line in it. Then it just does that all the time back and for back and forth. Seems like theres not enough pressure to keep the fluid flowing in 1 direction while the maste sucks in fluid from the res.

WHAT THE F**K IS GOING ON! I've tried 2 rebuilt master cylinders, two working master cylinders from other cars and nothing. I do not see any leakage from any of the lines in the engine back nor do any of them look kinked or bent. All connections are snug/tight as they should be.

Any assistance would be greatly appriciated this is issue is driving me up the wall...


PS. I've also tried a new ABS module and proportional valve.

 

[hvyman]

Can you blow some compressed air from the abs unit to the rear bleeders?

So the front bleed fine but the rears dont bleed at all?

Maybe try manual pumping with 2 people.

 

[OneJArpus]

Can you blow some compressed air from the abs unit to the rear bleeders?

So the front bleed fine but the rears dont bleed at all?

Maybe try manual pumping with 2 people.

Manual pump i've tried with two people, nothing. The brake pedal has this weird feeling. Its super soft then midway it goes rock hard (when all lines are connected). If i manually pump it and hold it and someone cracks the bleeder open, NOTHING happens. No air rushing out the pedal doesn't go down, nothing. Just stays like that.


I've ran compressed air through the brake lines from where they start at the master cylinder allll the way to the rear with both lines disconnected from the caliper and they both had air coming out of them at a steady stream.

To aid in the bleeding process should i compress all the calipers in again to see if that helps?

I've had this problem before but paid someone to look into it and when i got the car back it stopped, but the pedal felt weird. After driving a while i figured maybe there was some air in the line and when a friend helped me the second he cracked the bleeder open i heard a gurgle sound by the master cylinder and that was it (yes i was holding the brake pedal down)... no pressure at all. It had some pressure before as rusty rotors were getting cleaned as i drived but i felt like they werent 100%

I'm very mechanically inclined but for some reason this shit has got me STUMPED... bad

 

[hvyman]

Who rebuilt the master? Sounds like the master. Caliper wont matter as the master is what pushes the fluid.

Did the same thing with my nova. After having the company(nice billet one) rebuild the master 3 times went and got a cheap one from autozone and it was fine.

 

[OneJArpus]

Who rebuilt the master? Sounds like the master. Caliper wont matter as the master is what pushes the fluid.

Did the same thing with my nova. After having the company(nice billet one) rebuild the master 3 times went and got a cheap one from autozone and it was fine.

i've tried many different places for masters all the same issue. I've tried master cylinders off of working cars. Take them off a car swap it over nothing, put it back on the other car its fine. So something is wrong i just don't know what's wrong. I've tried adjusting the pedal, free play, and even the rod on the brake boost as a last resort and nothing.

 

[destrux]

Are the calipers all on the correct sides with the bleeder screws at the top of the caliper body?

Also, did you try removing the bleeder screws completely to make sure the holes in the screw and the hole in the caliper body are all open. It's not uncommon for rust or junk to plug up the bleeders. Especially when the bleeder screws face upward like on this car.

 

[hvyman]

Thats really odd. The brake system is fairly simple.

Nothing is mixed up for front to rear on the lines right?

Abs actuator if bad is built to go in the open position so even if it was bad you would still be able to bleed it.

Something i do at work is a gravity/suction type of bleeding. I use the big gatorade bottle. Cut a hole in the cap so a valve stem fits in tight and then take the valve out. Stick a hose that fits over tightly on the valve stem and tightly over the bleeder. just open the bleeder and start pumping.
I find that it works much better than the vac pumps. It also kinda puts a suction on the bottle. So before you pull the hose off, loosen the cap a tad on the bottle or else you will get a bit of a mess with the fluid thats in the hose.

 

[OneJArpus]

Are the calipers all on the correct sides with the bleeder screws at the top of the caliper body?

Also, did you try removing the bleeder screws completely to make sure the holes in the screw and the hole in the caliper body are all open. It's not uncommon for rust or junk to plug up the bleeders. Especially when the bleeder screws face upward like on this car.

Calipers are on the correct side with the bleeder screws @ the top. Both rear calipers are 3/4 yrs old no rust on them at all and the bleeders are new with the caliper. I have SS lines front & back as well. I have never taken the brake hard lines completely off of anything before.

Thats really odd. The brake system is fairly simple.

Nothing is mixed up for front to rear on the lines right?

Abs actuator if bad is built to go in the open position so even if it was bad you would still be able to bleed it.

Something i do at work is a gravity/suction type of bleeding. I use the big gatorade bottle. Cut a hole in the cap so a valve stem fits in tight and then take the valve out. Stick a hose that fits over tightly on the valve stem and tightly over the bleeder. just open the bleeder and start pumping.
I find that it works much better than the vac pumps. It also kinda puts a suction on the bottle. So before you pull the hose off, loosen the cap a tad on the bottle or else you will get a bit of a mess with the fluid thats in the hose.

^I can try that but i'm afraid that even doing that it wont help and even if i can get some pressure in the back that if i ever in the future want to bleed them i'll always have to do it this way. I like looking at the fluid coming out to make sure its clean clear etc. Then i feel it'll suck fluid into the line but push it back out with every pump. I just can't understand why this is happening. Anyone have a spare working master i can try? I've thought of putting old brake calipers on the car to see if maybe the calipers are the problem, i've even thought of replacing the brake lines again but i dont want to keep throwing money at this thing hoping its this or that. I just want to know what exactly is wrong.


I cant understand why i do not have full stroke on the master cylinder with the rear brake line bleeder open, i have full stroke when the front is open only. Sigh.. this is driving me crazy

 

[IBoughtASupra]

Did you bleed each line? No, I know it sounds like a dumb question, but I have bleed lines and fluid will come out but it had air in the line.

I will tend to bleed the brakes until I see clear fluid.

My source: Rebuilt all the calipers on my and converted all the lines to stainless steel Teflon -3 lines.

 

[jetjock]

I also pressure bleed from the calipers the way it's done on aircraft. Never fails. Bubbles prefer to go up you know...

 

[OneJArpus]

Did you bleed each line? No, I know it sounds like a dumb question, but I have bleed lines and fluid will come out but it had air in the line.

I will tend to bleed the brakes until I see clear fluid.

My source: Rebuilt all the calipers on my and converted all the lines to stainless steel Teflon -3 lines.

Bleed them how? If i open any of the front caliper bleeders and press the brake pedal it'll have great pressure and push the fluid out no problem. If i try that with the rear nothing at all and pedal doesn't feel any different.

I also pressure bleed from the calipers the way it's done on aircraft. Never fails. Bubbles prefer to go up you know...

I don't have the tool or current funds to buy it for 1 time use

 

[jetjock]

You don't have funds to buy a small garden sprayer? They're what, 15 or 20 bux?

 

[OneJArpus]

You don't have funds to buy a small garden sprayer? They're what, 15 or 20 bux?

hmmm i wasn't thinking in terms of that simple of a tool LMAO! i was thinking the pressure bleeder kits for the auto industry.... I'll go to home depot today

 

[metaphysico]

I have had this problem on every master cyl I have ever replaced on a supra. I have never gotten a good rebuilt master they install the wrong seal on the rear piston. Here is a easy test that I do when I get one from a parts place to test, you can test yours this way too(but I already know it does it by what you said).

I really need to do the write up I want to just don't have the pics needed, but I need to rebuild the one in my wifes car so I will get pics and do the write up then.


While at the counter (ie at parts place before buying) with no fluid in the master press the piston of the master all the way in (or with yours off car). Put two fingers over the two holes of the master. Release the piston while holding the holes, wait for 10 seconds and remove your fingers to see if there is any vacuum pulling on the rear most hole. If there is then the rear seal is wrong.

What I do is get a master from the parts place and test it. They always test bad doing this method. I don't give them the core. Get the new master and take it apart and take yours apart. You just push the piston in a little and remove the c-clip. Pull the rear piston out. Look at the seal on the rear piston of each master. You will notice they are not shaped the same, the one from the parts store will have a different looking seal its more of a square cut, the one that came out of the car is more of a triangle shape. Take the front piston out of the reman master and take the front seal off of that one and install it on the rear piston of your master. The front seal is always correct but the rear is not so just swap them and rebuild yours.

Given if you could get a rebuild kit this would be much easier but I cannot find them anymore for these. Lube the seals and the bore of your master, and I forgot to mention you need to check for any scratches or wear on the master inside bore if there are any use the reman unit instead. You can pick up a wheel cyl hone for under $10 and use it on your master bore to clean it up, use it like a piston hone. I know you probably don't have your core as you turned it in for the one you have now and for the amount of money those abs masters cost its a pain to have to do this but I have had to do it many times. The first time I had to go to a pull a part yard and get a master off a car and used it as the rebuildable core.


I know it sounds bad but normally I will return the thing back to the parts store, or I will get them to get me another so I can replace the front seal of my unit too. I know all this sounds bad to do to the parts place, but when they can't sell you a working unit its the only option you have left.

Well with all this fun said I think I have a spare master lying around I will get the pics and do a complete write up.

 

[OneJArpus]

I have had this problem on every master cyl I have ever replaced on a supra. I have never gotten a good rebuilt master they install the wrong seal on the rear piston. Here is a easy test that I do when I get one from a parts place to test, you can test yours this way too(but I already know it does it by what you said).

I really need to do the write up I want to just don't have the pics needed, but I need to rebuild the one in my wifes car so I will get pics and do the write up then.


While at the counter (ie at parts place before buying) with no fluid in the master press the piston of the master all the way in (or with yours off car). Put two fingers over the two holes of the master. Release the piston while holding the holes, wait for 10 seconds and remove your fingers to see if there is any vacuum pulling on the rear most hole. If there is then the rear seal is wrong.

What I do is get a master from the parts place and test it. They always test bad doing this method. I don't give them the core. Get the new master and take it apart and take yours apart. You just push the piston in a little and remove the c-clip. Pull the rear piston out. Look at the seal on the rear piston of each master. You will notice they are not shaped the same, the one from the parts store will have a different looking seal its more of a square cut, the one that came out of the car is more of a triangle shape. Take the front piston out of the reman master and take the front seal off of that one and install it on the rear piston of your master. The front seal is always correct but the rear is not so just swap them and rebuild yours.

Given if you could get a rebuild kit this would be much easier but I cannot find them anymore for these. Lube the seals and the bore of your master, and I forgot to mention you need to check for any scratches or wear on the master inside bore if there are any use the reman unit instead. You can pick up a wheel cyl hone for under $10 and use it on your master bore to clean it up, use it like a piston hone. I know you probably don't have your core as you turned it in for the one you have now and for the amount of money those abs masters cost its a pain to have to do this but I have had to do it many times. The first time I had to go to a pull a part yard and get a master off a car and used it as the rebuildable core.


I know it sounds bad but normally I will return the thing back to the parts store, or I will get them to get me another so I can replace the front seal of my unit too. I know all this sounds bad to do to the parts place, but when they can't sell you a working unit its the only option you have left.

Well with all this fun said I think I have a spare master lying around I will get the pics and do a complete write up.

i can tell you right off the bat, when bench bleeding it, with my finger over the port it has more vacum suction then pressure going out...

I didn't turn in my core yet so i have 2 master cylinders right now. I'm going to take both of them apart and compare the seals. If this works i'll paypal you the 8 bucks in my pp account right after just from saving me from insanity.

Then just returned the defective one

 

[jetjock]

Once you get the system clean and bled, a tip for avoiding the corrosion that eats bores and thus piston seals: once a year replace the reservoir fluid. Suction it and whatever crap there is out. You won't have to bleed even if drained to the bottom. By doing this my original master lasted the life of the car which was 22 years. Do the same with the clutch and if the flotation disc has disappeared buy another one.

 

[OneJArpus]

Once you get the system clean and bled, a tip for avoiding the corrosion that eats bores and thus piston seals: once a year replace the reservoir fluid. Suction it and whatever crap there is out. You won't have to bleed even if drained to the bottom. By doing this my original master lasted the life of the car which was 22 years. Do the same with the clutch and if the flotation disc has disappeared buy another one.

I've already flushed out clutch fluid yesterday, it was a yr old.

Brake fluid was going to get flushed then this happened. I'm upgrading my front brakes at the same time to cobra bbk...

 

[3p141592654]

I ordered a master cylinder rebuild kit from Toyota in Jan 2009. Are you saying they are now discontinued? I have yet to use it, because like JJ, my 20 year old one is still going fine, but I keep it just in case.

04493-14131 $59.24 1 Cylinder Kit, Brake Master w/anti-lock brakes 1987 - 1992

 

[OneJArpus]

^If my options don't work i'll look into the rebuild kit

 

[OneJArpus]

I have had this problem on every master cyl I have ever replaced on a supra. I have never gotten a good rebuilt master they install the wrong seal on the rear piston. Here is a easy test that I do when I get one from a parts place to test, you can test yours this way too(but I already know it does it by what you said).

I really need to do the write up I want to just don't have the pics needed, but I need to rebuild the one in my wifes car so I will get pics and do the write up then.


While at the counter (ie at parts place before buying) with no fluid in the master press the piston of the master all the way in (or with yours off car). Put two fingers over the two holes of the master. Release the piston while holding the holes, wait for 10 seconds and remove your fingers to see if there is any vacuum pulling on the rear most hole. If there is then the rear seal is wrong.

What I do is get a master from the parts place and test it. They always test bad doing this method. I don't give them the core. Get the new master and take it apart and take yours apart. You just push the piston in a little and remove the c-clip. Pull the rear piston out. Look at the seal on the rear piston of each master. You will notice they are not shaped the same, the one from the parts store will have a different looking seal its more of a square cut, the one that came out of the car is more of a triangle shape. Take the front piston out of the reman master and take the front seal off of that one and install it on the rear piston of your master. The front seal is always correct but the rear is not so just swap them and rebuild yours.

Given if you could get a rebuild kit this would be much easier but I cannot find them anymore for these. Lube the seals and the bore of your master, and I forgot to mention you need to check for any scratches or wear on the master inside bore if there are any use the reman unit instead. You can pick up a wheel cyl hone for under $10 and use it on your master bore to clean it up, use it like a piston hone. I know you probably don't have your core as you turned it in for the one you have now and for the amount of money those abs masters cost its a pain to have to do this but I have had to do it many times. The first time I had to go to a pull a part yard and get a master off a car and used it as the rebuildable core.


I know it sounds bad but normally I will return the thing back to the parts store, or I will get them to get me another so I can replace the front seal of my unit too. I know all this sounds bad to do to the parts place, but when they can't sell you a working unit its the only option you have left.

Well with all this fun said I think I have a spare master lying around I will get the pics and do a complete write up.

I did this, still no luck =/ i'm stuck... this problem is so annoying. Im getting fed up with this =/. The problem is before the ABS module i can say that much because i can see with the clear tube what happens to the fluid as it comes out of the abs pump to travel to the back wheels. I'm going to pull the lines one by one and either 1 replace them after i test them, maybe one of the connectors when tightened still isn't sealing but i cant see why that'll happen because i've put the vac lin on the exit port of the ABS pump, pumped it to -25... maybe i should post a video of whats happening