Stumped on brakes. Help!!!!

[Firsts tuner]

So I bled the brakes and I get a good firm pedal. Wait a few seconds(like literally 3seconds) and the pedal goes to the floor. I did the buddy method and I also put a valve stem in an old resivior cap and put a little air pressure to it and bled it that way. No help. I replaced the m/c and still no help. It might feel a little better but very little. The m/c I took off looked like a reman and was nearly new. I replaced it with a new not rebuilt one. I'm getting good fluid to all 4 corners. I just don't know what to do next. Are there any brake experts out there that can help me? Should I try another m/c? Oh and yes I did bench bleed the m/c before I hooked up the lines. Thanks, and Merry Christmas.

 

[mitsubishikid]

merry Christmas to you too.

based on your info it sounds like the one way valve on the booster is not working or not all the way.
did you check the valve, and its line for leaks already?

here is a link to some mod info on it from this site.
http://www.dsmtuners.com/forums/newbie-forum/291364-brake-booster-check-valve.html

 

[Henny101]

Sounds like you still have air in the lines or You have a leaky line somewhere

 

[Firsts tuner]

merry Christmas to you too.

based on your info it sounds like the one way valve on the booster is not working or not all the way.
did you check the valve, and its line for leaks already?

here is a link to some mod info on it from this site.
http://www.dsmtuners.com/forums/newbie-forum/291364-brake-booster-check-valve.html[/QUOTEe
]

Yes I did check the hose and found a crack at the end. Trimmed the hose back a little and checked it with a handheld vac tester and the check valve seems to be working. I am going to replace the new master cylinder tomorrow and bleed it all again. The m/c I bought had plugs with it. It says to install the two plugs into the outlets for the lines and pump till the pedal gets hard. Then remove one plug and install the line, and pump more till the pedal gets hard again. Repeat step two. Doesn't really seem like the air has anywhere to go like that. I used a couple old lines run back into the res. to bench bleed. Did I do something wrong there? I really appreciate the suggestions and please keep em coming. Thanks

 

[miguelmcv]

It sounds like air in the system, however is rare but could happen, is that you got a bad BMC, When I do any bleeding in my car, it doesn't matter if it's from the BMC or Clutch cylinder, I always dry the reservoir, which it has dirty oil, then I fill up with new oil (clean) and start bleeding, this way I know for sure when to stop, When I bleed the system, I don't stop bleeding till I see the clean oil coming out, and once I see the new oil then I keep going a couple of more bleeding to make sure all the air gets out.

Hope this helps to identify when you have reach the new oil and you know that you are doing good.

 

[My1GLaser]

What were the symptoms that caused you to be working on the brakes in the first place? Why are you replacing the MC? That is where I would start troubleshooting.

 

[Firsts tuner]

What were the symptoms that caused you to be working on the brakes in the first place? Why are you replacing the MC? That is where I would start troubleshooting.

When i got the car it had alot of problems. One of which being the brakes. The po said it had a busted hose at one of the calipers and that the res. was dry. I inspected it and found out that a banjo fittilg was missing a crush washer and was loose. I replaced the crush washer and tightened the fitting. I filled the resivior with new fluid and have bled them about 4 times so far. Being as how the res was empty, and now has new fluid I assumed that when I got new fluid to each corner I was good to go. I bought the new m/c at Autozone. Not my first choice but they were the only ones who had one. I did make sure it was new and not rebuilt. I do know that if i get a good pedal and hold it, it wont sink. If I start the car while holding the pedal it will sink a little.(Normal with the power assist if I'm not mistaken.) I'm gonna go ahead and get the new replacement they have on order for me today. We'll see what happens then. I may also try to do what was said above and run it dry completely and start from scratch. Thanks again

 

[FIBA M - EC17PSE]

Also did your buddy push the pedal all the way down to the floor? As that can also pop the seal in the master cylinder and cause this issue, ive seen many people do this and its very common for people to do, it only needs a light pump to push the air out

 

[Firsts tuner]

Also did your buddy push the pedal all the way down to the floor? As that can also pop the seal in the master cylinder and cause this issue, ive seen many people do this and its very common for people to do, it only needs a light pump to push the air out

I had my wife helping me at the time. She probably did. But I did use the other method afterwards. I took an old cap and installed a valve stem on it. Screwed that on top of the res., then put about 15psi or so to it. I let each corner run till the res. was almost empty. I don't know. I'm used to bleeding brakes on old 4x4's. DSM's are still pretty new to me. I will have her help me again and make sure she doesn't push the pedal all the way to the floor. Thanks

 

[Colt4G63 also]

Check all the caliper slider pins. It sounds to me like it pumps up, (bending a frozen caliper pin) then when you release the pedal the pin springs back straight, pushing the caliper piston back in. If this is the case, you'll find your pads worn at an angle.

Just to clarify, the caliper squishes down at an angle because one of the pins doesn't slide.

 

[ChiTownHussla]

^^^

Lube up all slide pins and tell us how the pads are wearing. that can help us help you narrow it down

 

[98zx23369]

When you bleed the brakes is there equal pressure at all the bleeders? or does one just drizzle out?

 

[Ryan james]

Try gravity bleeding it at the calipers, open up the bleeders one at a time starting with the right rear, then tap the caliper with a rubber mallet, air can get trapped in their, then do the left rear, then right front, then left front. After you see no more air bubbles coming out of the bleeders, make sure they are all closed then get into the car start it up and pump the brake pedal about 20 times, not hard but just regular, then shut it off and repeat the gravity bleeding process.

 

[Firsts tuner]

The pads are all new so I don't know for sure if they're wearing funny or not. Looks like someone put a lot of work into this thing before they parked it. On gravity bleeding I didn't think you could since there are so many ups and down's along the routing. And lastly there is equal pressure at the bleeders. I will hit it this evening and report back as to the situation. As always I really appreciate all the insight and suggestions.

 

[mitsubishikid]

If I were you i'd return the autozone m/c before it is too late.
if you want a good aftermarket master cylinder use the beck/arnley ones, they have vary good quality. and last time I checked, they can be picked up at rock auto for a decent price too.
I have not had a single beck/arnley part fail on me yet.
it's not that the autozone part is junk, it's that the parts they put in them
[most times] are not at oem spec, for example
I bought a clutch slave for my awd 1g at auto zone, and had more then a few headaches from it, guys kept telling me bleed it, or it's your t.o.b,etc until I tore it down and discovered that the spring inside was smaller then the oem one, I got an oem spec spring popped into the autozone piece problem solved, but bear in mind even if I had purchased a $1 billion dollar fancy bleeding tool it wouldn't have changed the fact that the spring was not at oem spec, as you could imagine I learned from this mistake.

also check the brake pedal assembly,and the push rod.
on a final note I do agree an improperly bled system can cause these symptoms, but I am willing to take your word that you obviously bled the system a few times.

 

[Ryan james]

Yeah, you can gravity bleed it, that is why I say to get back in and pump the pedal. I do it everyday to almost every car that I do brakes on except a toyota 4 piston caliper. Also I need to add are the rotor's worn or tapered in anyway that you can tell? If someone did the brakes on it and did not resurface the rotors, that will cause you to feel like the pedal is sinking also.

I have had a customer come in with a complaint, he said he put on a new mc and his pedal was sinking and he was losing fluid. After I inspected it there was no signs of leaking, so I pulled the mc away from the power booster and it was full of brake fluid. this being said I have seen many new parts right off the bat be bad.

 

[Firsts tuner]

Ok so I sent autozone their m/c back and drove forever to an orielly's that had one. Popped it on ( after the like 6th time I can now do this in under 7 minutes including bleeding.) tried out the gravity bleed method up front. I went so far as to remove the caliper and compress the piston just to be sure. Put it all back together and viola I have brakes! Haven't road tested it because it still needs a few little things to be streetable. I guess the Devil's in the details. Thanks again everyone I can mark this one as resolved!

 

[Ryan james]

well I am happy that you have it figured out! I have some problems on mine and if I cant figure them out i hope you can help me.

 

[Firsts tuner]

Yeah I actually just compressed the calipers and gravity bled it like you suggested. I went a step further by removing the calipers and making the banjo fittings the highest point, then cracked them a little. Kinda surprised to see how much air was trapped in there.

 

[Colt4G63 also]

It sounds like the calipers are probably on the wrong sides. Do your bleeders happen to point down?

 

[Firsts tuner]

It sounds like the calipers are probably on the wrong sides. Do your bleeders happen to point down?

No theyre not on upside down, but now the bleeders are broke off. Gonna be doing the gsx brake upgrade on it soon with ss lines. Apparently the bleeders were stressed from overtightening and snapped when I tried to tighten them the last time.

 

[Ryan james]

That is funny that you say that about the calipers being on upside down, I have had cars come into my shop several times like that and them saying they can't get a good brake pedal.

 

[VTDSM28]

You defiantly have air in the lines somewhere try bleeding the calipers by starting with the the caliper that's the farthest away from the mc and working your way up and keep fluid in the mc the entire time also check all the fittings.

 

[njclimber36]

It really sounds like the calipers were on the wrong side, putting the bleeders at the lowest point instead of the highest. Either way, I would like to know what the problem ended up being in case me or a friend has the same problem down the line I can help them out. Thanks and good luck.