Need to pump brakes in order to get pressure - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > Need to pump brakes in order to get pressure

FS: Wranger BRIGHT License Plate LED! Just $3! Great valueRIGID LED Light Blowout Sale - All Sizes, All Series, all End of Summer Sale, 20% OFF!

Reply
Unread 02-02-2010, 08:23 PM   #1
97DCZJ
Registered User
1997 ZJ 
 
Join Date: May 2009
Location: Long Island
Posts: 2,181
Need to pump brakes in order to get pressure

So I'm having this wierd pressure problem with my brakes. If I start the jeep, and press on the brakes, they go all the way down, n then the brake light turns on. If I pump it, the light goes off and pressure builds up a little in the pedal. It still doesn't feel normal though. It also happens everytime I have to use the brakes. It'll keep pressure for a little but it'll do the same thing again after a little bit of driving. I was told to bleed the brakes because it seems like there's air in the lines. I'm doing this tomorrow. I feel it might be the either the brake booster, or maybe the master cylinder.

__________________
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
97DCZJ is offline   Reply With Quote
Unread 02-02-2010, 09:08 PM   #2
jaytee
Registered User
1995 YJ Wrangler 
 
Join Date: Oct 2007
Location: MD
Posts: 337
It's the master cylinder, unless one of your calipers is leaking fluid. If the brakes were fine and then all of the sudden needed to be bled, it's because you have a leak somewhere. Master cylinder is a cheap and easy fix. Don't forget to bench bleed it first.
__________________
2004 GC Laredo
1995 YJ SE
jaytee is offline   Reply With Quote
Unread 02-02-2010, 09:14 PM   #3
97DCZJ
Registered User
1997 ZJ 
 
Join Date: May 2009
Location: Long Island
Posts: 2,181
Quote:
Originally Posted by jaytee View Post
It's the master cylinder, unless one of your calipers is leaking fluid. If the brakes were fine and then all of the sudden needed to be bled, it's because you have a leak somewhere. Master cylinder is a cheap and easy fix. Don't forget to bench bleed it first.
Well I'm not losing any fluid.
I thought the master cylinder would be the cause. And cheap/easy? I don't think so...
The cylinder I looked up, around 90 i believe, and not so easy. It looks as if the ABS module is in the way. It might not be, didn't really LOOK into yet.
And bench bleed? I have a feeling that has to do with a certain way of bleeding it if I'm replacing the master cylinder
__________________
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
97DCZJ is offline   Reply With Quote
Unread 02-02-2010, 09:23 PM   #4
jaytee
Registered User
1995 YJ Wrangler 
 
Join Date: Oct 2007
Location: MD
Posts: 337
I personally have not put a MC in a ZJ, but 90 bucks isn't too bad as far as parts go for a "luxury SUV". I did just put one in my WJ. It wasn't too bad. If the ABS pump is in the way, well then you will need to move it, which isn't a big deal as you are opening the system anyway. Just be careful disconnecting the lines. I would shoot them all with some PB Blaster and let it soak for overnight. Bench bleeding is a simple matter of bleeding the MC on a bench before you install it. It is a simple procedure with some basic tools, rubber hose, brake fluid, etc. I believe many master cylinders come with instructions inside the box. Most of the parts stores have bench bleed kits with a little plastic bottle and some tubing, adapters, etc. They are cheap. Even if 90 bucks is not cheap, it sure as hell is less than paying 120 dollars an hour labor for some dude to do it for you.
__________________
2004 GC Laredo
1995 YJ SE
jaytee is offline   Reply With Quote
Unread 02-02-2010, 09:24 PM   #5
JS97ZJ
Registered User
1997 ZJ 
 
Join Date: Dec 2009
Location: Dingmans Ferry, PA
Posts: 2,035
Check around the calipers and brake lines for leaks. If you don't find any, your master cylinder is probably leaking internally. Air in the lines is usually caused by opening the lines at the calipers when servicing them, or air getting into the master cylinder because it ran to low. Having air in the lines will give you a spongy pedal and not a complete fade with a warning light.

In any event don't drive it until you fix it.
JS97ZJ is offline   Reply With Quote
Unread 02-02-2010, 09:33 PM   #6
JS97ZJ
Registered User
1997 ZJ 
 
Join Date: Dec 2009
Location: Dingmans Ferry, PA
Posts: 2,035
Damn I type slow.....
JS97ZJ is offline   Reply With Quote
Unread 02-02-2010, 09:36 PM   #7
97DCZJ
Registered User
1997 ZJ 
 
Join Date: May 2009
Location: Long Island
Posts: 2,181
Quote:
Originally Posted by jaytee View Post
I personally have not put a MC in a ZJ, but 90 bucks isn't too bad as far as parts go for a "luxury SUV". I did just put one in my WJ. It wasn't too bad. If the ABS pump is in the way, well then you will need to move it, which isn't a big deal as you are opening the system anyway. Just be careful disconnecting the lines. I would shoot them all with some PB Blaster and let it soak for overnight. Bench bleeding is a simple matter of bleeding the MC on a bench before you install it. It is a simple procedure with some basic tools, rubber hose, brake fluid, etc. I believe many master cylinders come with instructions inside the box. Most of the parts stores have bench bleed kits with a little plastic bottle and some tubing, adapters, etc. They are cheap. Even if 90 bucks is not cheap, it sure as hell is less than paying 120 dollars an hour labor for some dude to do it for you.
Alright I appreciate the info. thanks a lot!

Quote:
Originally Posted by JS97ZJ View Post
Check around the calipers and brake lines for leaks. If you don't find any, your master cylinder is probably leaking internally. Air in the lines is usually caused by opening the lines at the calipers when servicing them, or air getting into the master cylinder because it ran to low. Having air in the lines will give you a spongy pedal and not a complete fade with a warning light.

In any event don't drive it until you fix it.
The light goes away after I pump it.
So you believe it's a bad MC?
__________________
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
97DCZJ is offline   Reply With Quote
Unread 02-02-2010, 11:33 PM   #8
ZJ5point2GCL
Registered User
1998 ZJ 
 
Join Date: Oct 2009
Location: Calgary
Posts: 3,392
if your doing an MC make sure you buy a line wrench, just using an open end can / will cause you allot of issues, so its not worth risking
ZJ5point2GCL is offline   Reply With Quote
Unread 02-02-2010, 11:36 PM   #9
ZJ5point2GCL
Registered User
1998 ZJ 
 
Join Date: Oct 2009
Location: Calgary
Posts: 3,392
Quote:
Originally Posted by 96DCZJ View Post
Well I'm not losing any fluid.
I thought the master cylinder would be the cause. And cheap/easy? I don't think so...
The cylinder I looked up, around 90 i believe, and not so easy. It looks as if the ABS module is in the way. It might not be, didn't really LOOK into yet.
And bench bleed? I have a feeling that has to do with a certain way of bleeding it if I'm replacing the master cylinder

the master cylinder has pretty good access, nothing in the way, it will take longer to bleed them than install the new MC
ZJ5point2GCL is offline   Reply With Quote
Unread 02-02-2010, 11:41 PM   #10
Planetcat
Registered User
2004 WJ 
 
Join Date: Jan 2010
Location: West of the Mississippi
Posts: 1,410
Check the booster while you have everything apart. I think I had the same symptoms like 5 years ago on my 96 XJ and it ended up being the brake booster and not the MC. The booster had lots of fluid in it and I picked up a remanufactured one from napa parts for something like $80. It would have been a quick install had I not tatered one of the rear lines and had to replace it. Bleeding the brakes will take longer than all the other parts combined. It's a fast fix.
__________________
2004 WJ 4.7L, 1959 CJ-5, 1990 XJ Limited, 1996 XJ (sold), 1989 YJ Wrangler 4.2L (Sold)
Planetcat is offline   Reply With Quote
Unread 02-02-2010, 11:44 PM   #11
BigE3
Registered User
1993 ZJ 
 
Join Date: Sep 2009
Location: Tombstone,Az
Posts: 1,014
Have you tried bleeding your brakes before you dump money somewhere you may not need too. I used to have to flush the fluid after every race because the fluid would break down. And since you're from LI with a jacked up jeep with big tires in stop and go traffic. That right there can cause you fluid failure and give you sponge foot.

Thats up to you before you jump into everything else. Its your money.
__________________
I like my Jeep, just like my women. 'Loose and Flexible'
BigE3 is offline   Reply With Quote
Unread 02-03-2010, 05:24 AM   #12
97DCZJ
Registered User
1997 ZJ 
 
Join Date: May 2009
Location: Long Island
Posts: 2,181
Quote:
Originally Posted by BigE3 View Post
Have you tried bleeding your brakes before you dump money somewhere you may not need too. I used to have to flush the fluid after every race because the fluid would break down. And since you're from LI with a jacked up jeep with big tires in stop and go traffic. That right there can cause you fluid failure and give you sponge foot.

Thats up to you before you jump into everything else. Its your money.
did you read the OP?
i said how im bleeding them today before i go and spend money.
and its not spongy, it just goes all the way down at first then pressure builds up after i pump it
__________________
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
97DCZJ is offline   Reply With Quote
Unread 02-03-2010, 07:51 AM   #13
vdub
Registered User
1994 ZJ 
 
Join Date: Nov 2008
Location: WI
Posts: 99
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?
vdub is offline   Reply With Quote
Unread 02-03-2010, 09:06 AM   #14
JrMechanic
Registered User
1993 ZJ 
 
Join Date: Oct 2008
Location: Lima, Ohio
Posts: 3,368
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?
If it were a vacuum leak, the pedal would be stiff. Not go to the floor.

Bleeding your brakes will be a waste of time. The brakes in your ZJ (or any vehicle) are a sealed system. Air doesn't just get introduced. Have you checked the fluid level? Are you positive you aren't losing fluid? If so, then yes it's the master cylinder.

The new MC will come with a bench bleeding kit and instructions.
__________________
Want to swap an NP242 or NP231 into your ZJ? Here's how:
http://www.jeepforum.com/forum/f13/n...pdated-685644/
JrMechanic is offline   Reply With Quote
Unread 02-03-2010, 09:09 AM   #15
vdub
Registered User
1994 ZJ 
 
Join Date: Nov 2008
Location: WI
Posts: 99
Quote:
Originally Posted by JrMechanic View Post
If it were a vacuum leak, the pedal would be stiff. Not go to the floor.

Bleeding your brakes will be a waste of time. The brakes in your ZJ (or any vehicle) are a sealed system. Air doesn't just get introduced. Have you checked the fluid level? Are you positive you aren't losing fluid? If so, then yes it's the master cylinder.

The new MC will come with a bench bleeding kit and instructions.

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.
vdub is offline   Reply With Quote
Reply
Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.