Hi all, i am helping a friend doing his brake job...but we notice a little problem after we bleed the brake system...

he has a 87 T2, we changed the front brake pads and bleed the system...we bleed it several times and the system is now clean and air free..however, he notice the pedal will sag after he push the brake and release it and push it again....(this is when he is driving..the pedal will sag...)..we thought we didn't get all the air out of the system, so we bleed it again...but the system is clean...

one thing i notice, when the car is OFF...his pedal is not building up pressure,...that means his booster is not good...but the brake works fine untill we bleed it...
another thing i notice, when the car is OFF and we trying to pump the pedal, the fluid in the master cylinder tank will go up and down...that's weird also...

anyway.....the system is not leaking anywhere...it's not leaking on the mastercylinder as well....

is it ok to get a used booster??..how much are a booster new??..how do we know if the booster is good or bad??

oh..forgot the mention, we can hear air leaking sound from the booster...so i am 100% sure it's the booster that's broken...but my friend keep saying it was working fine before the brake job...

any tips? or suggestion?? or info where i can get a used or cheap booster??


thanks

Richard

 

Did you bleed the whole system starting from the right rear and then left rear, right front, left front? That could be what's giving you trouble.

 

From your description I too would be looking at the booster and perhaps an internal leak in the master

 

so can internal master cylinder leak cause the booster not building up pressure?...

oh btw, i stared with Rear Left, RR, FR, and FL

Richard

 

Does the car have ABS?


-Ted

 

When bleeding brakes, start with the bleeder valve that's furthest from the master cylinder and work your way in, like BhamBill says.

I would suggest that doing it in the incorrect order has left air somewhere in the lines and that that is the cause of the problem. Re-bleed everything properly. Take your time doing it. Then see if the problem is still there. I have a hard time believing that a simple pad change and bleed (improper or not) would fubar an mc/booster assembly. Those are tough chunks of hardware and I haven't yet heard of one failing like that (keep in mind that I'm just beginning my 3rd year of rotary ownership.)

Good luck. Hope it was just bad execution - air in a line is a lot cheaper than replacing components.

ttyl,
Amur_

 

no the car does not have ABS...

when i did it for the first time, i started Right Rear, Left rear, front right and front left...because i think the furthest from the master cylinder...however if you look at the brake line...it goes from the master cylinder and went across the engine bay and then apray out to the rear...that makes the driver side rear the furthest place...

we took a lot of time bleeding the system...now the fluid is all clear and bubble free...i am going to get a new master for him and see if that will fix the problem....

hopefully it's not the booster...

Richard

 

If the brake master cylinder is original, I would highly recommend changing it too...



-Ted

 

got it fixed...it was a internal leaking brake master cylinder....
i didn't even know a leaking master cylinder will cause the brake booster not holding pressure....it is very weird...
got the parts from a local parts store ...part was 90 bucks... a little cheaper than dealer parts...but a little expensive for aftermarket parts...oh well..got it the same day...so.....everything is good....

thanks for the help guys..


Richard