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Brake booster????
Posted: Thu Apr 02, 2009 3:28 pm
by fat496
Hi Guys.
Just a quick Q, i'm having serious brake issues at the moment. pedal goes almost to the floor before stopping the car, but ive bled brakes twice now and doesn't seem to be any air in them. pedal is firm until i start the car then almost hits the firewall when booster gets vacuum. tend to think i need a new booster, but if it's stuffed shouldn't the pedal be more firm than usual??? Forgive my ignorance, just want another opinion before i go buy a booster. Vehicle is 1990 Daihatsu Feroza and yes i should have posted this in the Daihatsu section but no one answers quick enough there
Posted: Thu Apr 02, 2009 7:04 pm
by RAY185
Sounds like master cylinder is cactus.
Posted: Thu Apr 02, 2009 11:30 pm
by lump_a_charcoal
Yeah, you have a hole in your diaphragm maybe...
Posted: Fri Apr 03, 2009 7:46 am
by smithie
If the feroza's have a dual piston master cylinder it sounds like the first piston is stuffed. I'd whip the MC off and open it up and check the seals. Should only need a set of circlip pliers to get into it.
Re: Brake booster????
Posted: Fri Apr 03, 2009 8:27 am
by mkpatrol
fat496 wrote:Hi Guys.
Just a quick Q, i'm having serious brake issues at the moment. pedal goes almost to the floor before stopping the car, but ive bled brakes twice now and doesn't seem to be any air in them. pedal is firm until i start the car then almost hits the firewall when booster gets vacuum. tend to think i need a new booster, but if it's stuffed shouldn't the pedal be more firm than usual??? Forgive my ignorance, just want another opinion before i go buy a booster. Vehicle is 1990 Daihatsu Feroza and yes i should have posted this in the Daihatsu section but no one answers quick enough there
When you have the engine off, no vacuum left, if you hold your foot on the pedal does it slowly start to sink to the floor?
If it does its the master clyinder.
Once the booster has vacuum it will accellerate this process.
Posted: Fri Apr 03, 2009 8:33 am
by fat496
no doesn't sink to the floor, and also pumping brakes can hear hissing sound (Engine off), which leans me towards booster. if i'm driving and pump pedal a few times it firms up noticably.
Posted: Fri Apr 03, 2009 1:48 pm
by mavzilla
sounds like you broke the primary spring in the master cylinder ., or you have air in the system. it is not a booster problem with what you have described. blank of all brake lines with clamps and test, if ya got a full pedal ,release each clamp and test pedal pressure, when you notice a big drop in pedal you might have found the problem
Posted: Fri Apr 03, 2009 7:39 pm
by Ruffy
fat496 wrote:no doesn't sink to the floor, and also pumping brakes can hear hissing sound (Engine off), which leans me towards booster. if i'm driving and pump pedal a few times it firms up noticably.
They're both normal.
The cannot make your pedal travel further but it will excentuate a fault.
All your symptoms point to a master cylinder
Posted: Tue Apr 07, 2009 8:18 am
by fat496
had a play with it on the weekend rebled system but still same problem. basically it seems to me that there's still air in the system. have bled it twice now but it's like there is air in the actual master cyl still. shouldn't it bleed out when i'm cracking the bleed nipples at calipers/wheel cyls?
Posted: Tue Apr 07, 2009 9:08 am
by mkpatrol
fat496 wrote:had a play with it on the weekend rebled system but still same problem. basically it seems to me that there's still air in the system. have bled it twice now but it's like there is air in the actual master cyl still. shouldn't it bleed out when i'm cracking the bleed nipples at calipers/wheel cyls?
Not always, sometimes you have to bleed the master first at the unions.
I always bench bleed a master cylinder before I fit it.
Same process as at the calipers, pushdown on the pedal, close union, release pedal, depress pedal, release uinon ect.