Need to pump brakes in order to get pressure - Page 2 - JeepForum.com
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post #16 of 41 Old 02-03-2010, 09:20 AM
JrMechanic
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Quote:
Originally Posted by vdub View Post
Not from what i have heard. There was a poster on here a while back on here that had a soft brake pedal that would go all the way to the floor. He also had the same symptoms of a vacuum leak and found the leaks and fixed them. this also fixed his soft brake pedal.

If the MC was bad the pedal would not gain pressure by pumping it. it would keep going to the floor regardless of if you pump it or not.
Go pump your brake pedal with the engine off, then tell me a vacuum leak is going to give you a soft pedal

Sure, a total MC failure will yield no brake pressure. However seals get old and leak without totally failing.


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post #17 of 41 Old 02-03-2010, 09:43 AM
vdub
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what do you mean. when i pump my brakes with the car off they are stiff.. when i start to jeep up is when it gets soft.

i found this old thread about bleeding the abs pump and maybe having flow-by in the pump itself...

http://www.jeepforum.com/forum/f13/m...htmare-526360/
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post #18 of 41 Old 02-03-2010, 09:58 AM
JrMechanic
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Quote:
Originally Posted by vdub View Post
what do you mean. when i pump my brakes with the car off they are stiff.. when i start to jeep up is when it gets soft.

i found this old thread about bleeding the abs pump and maybe having flow-by in the pump itself...

http://www.jeepforum.com/forum/f13/m...htmare-526360/
Thank you for further supporting my point while not even knowing what you're talking about

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post #19 of 41 Old 02-03-2010, 10:23 AM
vdub
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Quote:
Originally Posted by JrMechanic View Post
Thank you for further supporting my point while not even knowing what you're talking about
your welcome my good sir.. my and brake systems are like obama and a good president... they just dont mix.
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post #20 of 41 Old 02-03-2010, 10:32 AM Thread Starter
97DCZJ
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Quote:
Originally Posted by vdub View Post
Could be a vacuum leak.

Does your heat go to defrost when your accelerating or putting load on your jeep? Also does your cruise conrol work?
Yes. I always keep forgetting to make a post about the heat going to defrost when I accelerate hard. The cruise control DOES work too.

as for pumping the brake while the engine is off, the pedal gets more stiff. but once I start the jeep up, the pedal drops to the ground, and I have to pump a few times for pressure to build up, but still feels soft, not stiff where it should be.

1997 Grand Cherokee Orvis: V8 5.2L, stock.
(Sold) 1998 Cherokee Sport: 4.0L I6, Stock.
(Sold) 1990 Cherokee: 4.0L I6, 4.5" Lift, 33" BFG's.
(Sold) 1997 Grand Cherokee Limited: V8 5.2L, 2" BB, 31" Dick Cepeks.
(Sold) 1999 Grand Cherokee Laredo: Build Thread; V8 4.7L, Stock.
(Sold) 1996 Grand Cherokee Laredo: Build Thread; V8 5.2L ,3.5" lift, 32" Tires
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post #21 of 41 Old 02-03-2010, 10:43 AM
vdub
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when was the last time you replaced your brake lines.. i was just reading another thread saying the oem rubber brake lines can stretch and cause a soft brake pedal
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post #22 of 41 Old 02-03-2010, 10:48 AM Thread Starter
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which brake lines?

well...either way, i never replaced any. lol
they could cause a soft brake pedal, but what's the reason for everytime i first press the brake, it goes to the floor with the Brakes light coming on, and then after I pump the brake a few times, it builds up pressure?
I know the Brake light is letting me know I have a pressure leak somewhere, and if I had a soft brake pedal from the rubber brake lines stretching, I shouldnt be able to press the brake all the way down

1997 Grand Cherokee Orvis: V8 5.2L, stock.
(Sold) 1998 Cherokee Sport: 4.0L I6, Stock.
(Sold) 1990 Cherokee: 4.0L I6, 4.5" Lift, 33" BFG's.
(Sold) 1997 Grand Cherokee Limited: V8 5.2L, 2" BB, 31" Dick Cepeks.
(Sold) 1999 Grand Cherokee Laredo: Build Thread; V8 4.7L, Stock.
(Sold) 1996 Grand Cherokee Laredo: Build Thread; V8 5.2L ,3.5" lift, 32" Tires
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post #23 of 41 Old 02-03-2010, 10:53 AM
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yeha. idk. i was just searching threads... i have the exact same problem with my brakes that you have with yours... right down to the brake light
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post #24 of 41 Old 02-03-2010, 01:11 PM Thread Starter
97DCZJ
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Okay well I just bled them, n fixed my problem. Mustve been air in the lines because they're stiff and the pedal moves I would say an inch or two

1997 Grand Cherokee Orvis: V8 5.2L, stock.
(Sold) 1998 Cherokee Sport: 4.0L I6, Stock.
(Sold) 1990 Cherokee: 4.0L I6, 4.5" Lift, 33" BFG's.
(Sold) 1997 Grand Cherokee Limited: V8 5.2L, 2" BB, 31" Dick Cepeks.
(Sold) 1999 Grand Cherokee Laredo: Build Thread; V8 4.7L, Stock.
(Sold) 1996 Grand Cherokee Laredo: Build Thread; V8 5.2L ,3.5" lift, 32" Tires
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post #25 of 41 Old 02-03-2010, 04:46 PM
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The problem will come back. As I said, air doesn't just magically appear in the lines, it has to be introduced from somewhere. Being that bleeding your brakes fixed the problem, I'd say the master cylinder has a slight leak allowing air to be introduced into the system. That explains why it's fixed now.

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post #26 of 41 Old 02-03-2010, 08:07 PM Thread Starter
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Well I also just replaced my driver side caliper and only bled that caliper. none of the others

prob shouldve mentioned this in the beginning, shouldnt i have lol

1997 Grand Cherokee Orvis: V8 5.2L, stock.
(Sold) 1998 Cherokee Sport: 4.0L I6, Stock.
(Sold) 1990 Cherokee: 4.0L I6, 4.5" Lift, 33" BFG's.
(Sold) 1997 Grand Cherokee Limited: V8 5.2L, 2" BB, 31" Dick Cepeks.
(Sold) 1999 Grand Cherokee Laredo: Build Thread; V8 4.7L, Stock.
(Sold) 1996 Grand Cherokee Laredo: Build Thread; V8 5.2L ,3.5" lift, 32" Tires
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post #27 of 41 Old 02-03-2010, 08:15 PM
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Yeah, probably That pretty much changes everything.

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post #28 of 41 Old 02-03-2010, 08:30 PM Thread Starter
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Quote:
Originally Posted by JrMechanic View Post
Yeah, probably That pretty much changes everything.
haha. it was happening before I replaced that caliper tho too. but I replaced the caliper because I know it's been bad for awile

1997 Grand Cherokee Orvis: V8 5.2L, stock.
(Sold) 1998 Cherokee Sport: 4.0L I6, Stock.
(Sold) 1990 Cherokee: 4.0L I6, 4.5" Lift, 33" BFG's.
(Sold) 1997 Grand Cherokee Limited: V8 5.2L, 2" BB, 31" Dick Cepeks.
(Sold) 1999 Grand Cherokee Laredo: Build Thread; V8 4.7L, Stock.
(Sold) 1996 Grand Cherokee Laredo: Build Thread; V8 5.2L ,3.5" lift, 32" Tires
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post #29 of 41 Old 02-03-2010, 11:41 PM
vdub
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How can you tell if a caliper is bad.. After jr's insight I think mine could be a bad MC. How can I test the MC. If the brake booster fails doesn't the pedal get really stiff??

I need to fix this asap its really starting to piss me off..
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post #30 of 41 Old 02-04-2010, 05:03 AM Thread Starter
97DCZJ
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I can tell the caliper was bad because it was kinda seized up a little. It was hard to spin the wheel when it was in the air. n only that tire, no others

1997 Grand Cherokee Orvis: V8 5.2L, stock.
(Sold) 1998 Cherokee Sport: 4.0L I6, Stock.
(Sold) 1990 Cherokee: 4.0L I6, 4.5" Lift, 33" BFG's.
(Sold) 1997 Grand Cherokee Limited: V8 5.2L, 2" BB, 31" Dick Cepeks.
(Sold) 1999 Grand Cherokee Laredo: Build Thread; V8 4.7L, Stock.
(Sold) 1996 Grand Cherokee Laredo: Build Thread; V8 5.2L ,3.5" lift, 32" Tires
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