Brake Master Cyl or booster?

[Squshiee1]

i have had a problem with my rodeo, its been happening for a little while. Go Figure another problem. :rolleyes:
I have just replaced my master cylinder and i am still getting "mushy" brakes. They are sort of stiff if i hit them hard and fast. but if i leave my foot on the pedal for more than a couple of seconds, it gets fairly weak.

could it be the booster? i have already bleed the brakes more than once, no bubbles, not even tiny ones.

pads and rotors are new. When i first got my brakes the response was amazing! but now it just sucks.

its really easy to brake, just no pressure. i can have my foot to the floor and it will never lock up, unless its dirt or snow. not even in rain.

[mattzj98]

idk, doesn't really sound like a booster.. a vacuum leak to the booster maybe? is it hissing? if it were the booster itself, it would be extremely hard to brake, like u'd have to stomp on the brake pedal (wonder how i know) to build pressure urself when thats out..

[Rick]

wheel cylinders???

[mattzj98]

an isuzu being an isuzu?? I THINK SO! :P

[Rick]

From your description I'm not so sure the master cylinder was the problem because this problem basicly still exits. I would be more apt to look for frozen caliper pistons, frozen caliper slide pins, worn out rotors and brake pads. The brake proportioning valve could also be stuck causing only front or rear brake action. Bleeding the system with the engine running often frees this valve. (the hint here is that the other shop wanted to test brake pressure leading me to think that they couldn't get a decent squirt of fluid out of either the front or rear bleeders)(maybe this machine exists but I never saw one nor had use for it).

For your safety and your family I would strongly suggest that this Trooper's brake system be totally checked. I know my answer to your question is of general nature but without being there I can't be sure of your problem and I will not guess on a saftey issue.

I don't expect you to accept since I didn't answer you completely. If you wish get back to me and I will opt out and see if another expert would care to tackle this

Read more: I have a 99 isuzu trooper. Brake pedal went almost to floor. - JustAnswer http://www.justanswer.com/car/1j9cn-99-isuzu-trooper-brake-pedal-went-almost-floor.html#ixzz1pce2NGg4
started Googling!!!!!!

[Rick]

Notes

BLEEDING BRAKE HYDRAULIC SYSTEM
A bleeding operation is necessary to remove air from the hydraulic brake system whenever air is introduced into the hydraulic system. It may be necessary to bleed the hydraulic system at all four brakes if air has been introduced through a low fluid level or by disconnecting brake pipes at the master cylinder. If a brake pipe is disconnected at one wheel, only that wheel cylinder/caliper needs to be bled. If the pipes are disconnected at any fitting located between the master cylinder and brakes, then the brake system served by the disconnected pipe must be bled.

For 4-Wheel Antilock Brake System (ABS) equipped vehicle, be sure to remove the ABS main fuse 40A located at the relay and fuse box before bleeding air. If you attempt to bleed air without removing the main fuse, air cannot be let out thoroughly, and this may cause damage to the hydraulic unit. After bleeding air, be sure to replace the ABS main fuse back to its original position.
Set the parking brake completely, then start the engine. NOTE: The vacuum booster will be damaged if the bleeding operation is performed with the engine off.
Remove the master cylinder reservoir cap.
Fill the master cylinder reservoir with brake fluid. Keep the reservoir at least half full during the air bleeding operation
Always use new brake fluid for replenishment.
In replenishing brake fluid, take care that air bubbles do not enter the brake fluid. When the master cylinder is replaced or overhauled, first bleed the air from the master cylinder, then from each wheel cylinder and caliper following the procedures described below.

Bleeding The Master Cylinder

Disconnect the rear wheel brake pipe (1) from the master cylinder. Check the fluid level and replenish as necessary. If replenished, leave the system for at least one minute.
Depress the brake pedal slowly once and hold it depressed.
Completely seal the delivery port of the master cylinder with your finger, where the pipe was disconnected then release the brake pedal slowly.
Release your finger from the delivery port when the brake pedal returns completely.
Repeat steps 7 through 9 until the brake fluid comes out of the delivery port during step 7. NOTE: Do not allow the fluid level in the reservoir to go below the half-way mark.
Reconnect the brake pipe (1) to the master cylinder and tighten the pipe.
Depress the brake pedal slowly once and hold it depressed.
Loosen the rear wheel brake pipe (1) at the master cylinder.
Retighten the brake pipe, then release the brake pedal slowly.
Repeat steps 13 through 15 until no air comes out of the port when the brake pipe is loosened NOTE: Be very careful not to allow the brake fluid to come in contact with painted surfaces.

Bleed the air from the front wheel brake pipe connection (2) by repeating steps 7 through 16.

Bleeding The Caliper

Bleed the air from each wheel in the order listed below:

Right rear caliper
Left rear caliper
Right front caliper
Left front caliper Conduct air bleeding from the wheels in the above order. If no brake fluid comes out, it suggests that air is mixed in the master cylinder. In this case, bleed air from the master cylinder in accordance with steps 7 through 17, and then bleed air from the caliper.

Place the proper size box end wrench over the bleeder screw.
Cover the bleeder screw with a transparent tube, and submerge the free end of the transparent tube in a transparent container containing brake fluid.
Pump the brake pedal slowly three (3) times (once/sec), then hold it depressed.
Loosen the bleeder screw until fluid flows through the tube.
Retighten the bleeder screw.
Release the brake pedal slowly.
Repeat steps 21 through 24 until the air is completely removed. It may be necessary to repeat the bleeding procedure 10 or more times for front wheels and 15 or more times for rear wheels.
Go to the next wheel in the sequence after each wheel is bled. Be sure to monitor reservoir fluid level.
Depress the brake pedal to check if you feel "sponginess" after the air has been removed from all wheel cylinders and calipers. If the pedal feels "spongy", the entire bleeding procedure must be repeated.
After the bleeding operation is completed on the each individual wheel, check the level of the brake fluid in the reservoir and replenish up to the "MAX" level as necessary.
Attach the reservoir cap. If the diaphragm inside the cap is deformed, reform it and install.
Stop the engine.



Read more: I have a 99 isuzu trooper. Brake pedal went almost to floor. - JustAnswer http://www.justanswer.com/car/1j9cn-99-isuzu-trooper-brake-pedal-went-almost-floor.html#ixzz1pcfL7mkB

[Rick]

might help ya!!!

[mattzj98]

My first thought honestly was low fluid / needs bleed but he says he did..

[Rick]

needs bleed but he says he did.
but did he do it right?????

[mattzj98]

does he ever?

[Rick]

:lmao::lmao::lmao::lmao::lmao::confused::confused: :confused:Not sure

[mattzj98]

I forgot you're somewhat new :P

haha Idk, Chase, did you do it right?

[Squshiee1]

i bought a chiltons manual a while back, i followed the instruction perfectly, the only difference from the one that tricky posted and my manual was.... that i needed to leave my car off, don't start it.

fluid is correct level, correct fluid dot 3, all of the fluid coming out of the lines is clean.
Does someone want to help me on an afternoon project? i think i need to try it with someone that has done this before.
i have done it on a bug, but not on a vehicle with a booster.

[Rick]

NOTE: The vacuum booster will be damaged if the bleeding operation is performed with the engine off.
engine needs to be running

[Brody]

To add to what Rick posted, the little $5 brake bleeder kits that you get at an auto parts store actually work very well. If you close off the bleeder valve with the adapter and set the hose/bleeder assembly up per instructions, then crack the valve, the system remains closed. This works very well when you are doing something like replacing the front or rear brake pads and just need to compress the caliper when you install the new pads. Just watch that the level in the master cylinder stays pretty full when you are doing this so you don't suck air into the system through the master. When the new pads are installed and the caliper is back over the rotor, simply close the bleeder.

[Squshiee1]

the brakes have already been instaled for a while now.
my braking system is a little bit different than a trooper, my moms trooper has a different size and style booster and Master.

maybe sometime this week or weekend i can try to bleed them with the car running, or with a brake bleeding tool.

[Brody]

You are welcome to borrow the little set up that I have, Chase. I would just need it back pretty soon as I use it quite a bit. They are pretty cheap, though, but if you don't want to spend the $$, the offer is there. simple to use.

[Squshiee1]

i should be able to make it over there this weekend.
how simple to use?
i should be down there sunday and next week.

[Robert B]

hhmm my idea of oil in the drum wont work if your truck follows what i fond online and its 4wheel disk lol ...umm i dont know oh does it have ASB for 1 lol that wont let it lock up and some cars like the 95 nissan pathfinder we have just will not lock em no matter what nor does my blazer ...and the pathfinder has real soft brakes to be but they stop fine so the question i have is does it stop fast and fine and just has a soft pedal or does is not stop very well......also does it ever loose fluid??? ...uhh can those lines get weak and expand when under braking pressure???? thats all i know to look for

[Squshiee1]

it has rear wheel abs, it does not brake very fast when the pedal is to the floor. no fluid loss either.

[Brody]

how simple to use?

It is about as simple as simple gets. In other words, I can use it..:lmao:

You have a small clear bottom with a hose attached to it and a magnet on it. You set the bottle higher than the brake caliper a body panel or frame point, run the hose down to the bleeder, and then insert a "V" shaped plastic fitting into the end of the bleeder valve. Cracking the bleeder forces the air up through the line to the bottle. You watch the line and when nothing but fluid is showing (no air bubbles), the caliper is bled. The only trick is to keep fluid in the master cylinder so that more sir doesn't go into the line. Takes about 10-15 minutes to do all four wheels, working your way back toward the master cylinder.

Just hose down the bleeders with some PB Blaster so that the little bastards don't break off flush with the caliper....:D

[2000Durango]

if it has rear drum brakes you can try to adjust them if they are way out of adjust it can cause a low brake pedel..

[Brody]

That little cheapo bleeder did the trick for Chase.

[Popsgarage]

So he did get it fixed????

[Brody]

Yup. Loaned him that little $5 bleeder and it worked great. They also used it on his dad's VW that also had brake problems and it fixed that one, too.

[Popsgarage]

Nice! He's a good kid. Gonna be a decent mechanic someday.