Rear Brakes bleeding issue - 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 CJ Forum > Rear Brakes bleeding issue

FS: Jeep Fog Light LED Bulbs! Several Brightness Options! Clayton Off Road JK Short Arm Suspension Kits~Artec JK 1 TON SWAP~

Reply
Unread 10-13-2008, 09:50 AM   #1
Jonnyhaku
Registered User
 
Join Date: Jan 2005
Location: Washington Township, NJ
Posts: 36
Rear Brakes bleeding issue

weird one for you here guys:

My frame up, we're just finishing up the necessities for her to be driven on her maiden voyage.

Front brakes bleed fine...rear brakes won't get much fluid or pressure.

We bench bled the master cylinder (repeated the process a few times...get plenty of push at the master-cylinder).

We disconnected the back end of the proportioning valve -- get plenty of fluid out the back of it (where it heads to the rear lines).

But, we cannot get more than a few drops out of the rear lines at the wheels. Not much is coming out of the master cylinder in the rear reservoir either during bleeding, so we know it's not filling up the rear-lines like you'd expect.

In diagnosing connections/blockage, etc -- we blew air from the the rear-line connection (at the prop. valve) to each rear wheel cylinder separately, air blew freely right through. So, I have connectivity to the rear lines beyond the splitter w/o blockage.

Perplexed...

ideas?

~Jon

__________________
[B]Can't get away from these things[/B]
85 CJ7 Frame up Restoration in progress
Jonnyhaku is offline   Reply With Quote
Unread 10-13-2008, 10:22 AM   #2
Smtty58
Registered User
1990 YJ Wrangler 
 
Join Date: Aug 2007
Location: Monson, Mass.
Posts: 723
Possibly the spool in the prop valve has tripped and needs to be pulled back out.
__________________
90 YJ, 4.2, AX-15
86 K1500, 305, 700R4

Western Mass. 4x4
Smtty58 is offline   Reply With Quote
Unread 10-13-2008, 10:23 AM   #3
NHwheelin
Registered User
1991 XJ Cherokee 
 
Join Date: Nov 2007
Location: NewHampshire
Posts: 526
The only thing I can think of is that there might be an air leak somewhere. It could be as simple as a connection not fully tightened or a pin hole in the rubber line to the t connection on the rear axle. Have you tried holding the button on the porp. valve closed while bleeding the rear breaks?
__________________
91 XJ Limited (stock for now)
NHwheelin is offline   Reply With Quote
Unread 10-13-2008, 11:04 AM   #4
jatepper
Registered User
1985 CJ7 
 
Join Date: Mar 2007
Location: Tucson, AZ
Posts: 2,274
OK. To me this sounds like a prop valve problem. The proportioning valve has a bias sensor which trips whenever it senses an imbalance in the brake lines. For example, if the rear brake line springs a leak, the pin in the prop valve will switch to the rear, which blocks flow to the rear brakes to keep the fluid from leaking out completely.

I had a similar problem, so this is how I know. JeepHammer made the recommendation to bleed the front brakes first to "reset" the pin in the prop valve. Generally when bleeding brakes, you start from the furthest wheel from the MC (rear passenger) then work you way up from furthest wheel to closest wheel (rear driver, front passenger, front driver). However, with the CJ set up and prop valve, this is not necessary. Go ahead and bleed the fronts (passenger side first) and then bleed the rears. In AMC's case, it really does not matter which rear wheel you bleed first because the both come off the same brake line and T-off at the junction attached to the top of the axle housing.

Sounds backwards, but worked well for me when I had problems. Again, this process will reset the pin in your prop valve, which is likely the culprit.

EDIT- When you turn on your ignition with the ebrake off, do you get the brake warning light in the cluster?
__________________
1985 Jeep CJ-7
Automatic-258 I6- Detroit lockers front/rear - Superior 1-piece axles, Ramsey Pro 9000 Winch, Quick Disconnects, 33 BFG AT's, 4.10 gears, Howell TBI, DUI HEI Ignition, Ground Pounder Rear Bumper / Tire Carrier Combo, Handen Fab integrated winch plate front bumper w/hoop, ORF weld-in front sport cage.

USMC 1999-2004 Semper Fi!

Hood Hi-Lift Jack Mounts for CJ/YJ/TJ/JK

Torchmate CNC Plasma Table Build / Projects

The Target Man, LLC - AR500 Shooting Targets
jatepper is offline   Reply With Quote
Unread 10-13-2008, 12:00 PM   #5
Mike Romain
Registered User
1986 CJ7 
 
Join Date: Nov 2007
Location: Off the Grid in Chester Grant, Nova Scotia, Canada
Posts: 13,152
The insides of the flex hose at the back can come loose and block the flow under pressure. Fluid is a bit different for flow than air.

Maybe the bleeder holes are plugged up? I have had that happen more than once.
__________________
Mike
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
Mike Romain is offline   Reply With Quote
Unread 10-14-2008, 08:46 AM   #6
Jonnyhaku
Registered User
 
Join Date: Jan 2005
Location: Washington Township, NJ
Posts: 36
Thanks for the responses guys.

In terms of diagnosis:

I did a lot of reading on the proportioning valve yesterday after I initially gave into just writing "can someone help me out here!" haha

JeepHammer's explanation of the spool-valve on the "how to bleed brakes" thread, sounds like the culprit. The only problem was, we did the fronts first...but I'm assuming the spool is stuck to the fronts/not setting back to the back b/c of the uneven pressure and some debris keeping it stuck to the fronts. I may try the "do one front first then one rear next to keep the valve moving" method. I'm tempted to take the valve out and do a thorough cleaning, but he warns about incessant leaking following replacement.

When I took the p-valve off, we blew air into the inlet for the front and rear to make sure it wasn't a blockage in there, both blew right through, and the valve was actuated each time I blew air into the fronts, not the rears though...I'm thinking if we cannot get the 1st method I mentioned here to work (1 front, 1 rear, 1 front, 1 rear), the next attempt would be to force that pin to stay closed while bleeding the rears...channel locks maybe?

The ENTIRE system is brand new (I rebuilt many elements of the CJ, but the braking-system I thought would benefit from getting all new parts). The ONLY part that is not new, only for lack of being able to locate a solid replacement is the proportioning-valve. Go figure. I'll update after we work this problem out, let you guys know what came of it. Friday we'll be at the shop.

~Jon
__________________
[B]Can't get away from these things[/B]
85 CJ7 Frame up Restoration in progress
Jonnyhaku is offline   Reply With Quote
Unread 10-14-2008, 09:03 AM   #7
Mike Romain
Registered User
1986 CJ7 
 
Join Date: Nov 2007
Location: Off the Grid in Chester Grant, Nova Scotia, Canada
Posts: 13,152
They make a special tool to hold the pin in the combo valve from moving when you bleed the brakes. You can just have someone hold it with pump pliers or use a hose clamp and a penny like I have done before or even get the tool.
__________________
Mike
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
Mike Romain is offline   Reply With Quote
Unread 10-14-2008, 11:00 AM   #8
Group_er
Registered User
1986 CJ7 
 
Join Date: Sep 2008
Location: Victoria BC
Posts: 235
I had the same problum years ago in shop class. It ended up being the rod that pushes out of the vacuum booster booster, into the mster cylnder was out of adjustment. to short.
Group_er is offline   Reply With Quote
Unread 10-27-2008, 09:30 AM   #9
Jonnyhaku
Registered User
 
Join Date: Jan 2005
Location: Washington Township, NJ
Posts: 36
results

Wierd/mixed results to using JeepHammer's recommendations...

1) Did the front's first, then rears...didn't work.

2) Did the 1-front, 1-rear, 1-front, 1-rea
__________________
[B]Can't get away from these things[/B]
85 CJ7 Frame up Restoration in progress
Jonnyhaku is offline   Reply With Quote
Unread 10-27-2008, 09:38 AM   #10
Jonnyhaku
Registered User
 
Join Date: Jan 2005
Location: Washington Township, NJ
Posts: 36
results

Wierd/mixed results to using JeepHammer's recommendations...

1) Did the front's first, then rears...didn't work.

2) Did the 1-front, 1-rear, 1-front, 1-rear method...got brake fluid to the rear brakes - but only w/ the below methods...read-on.

We bled, and bled, and bled until we got no air-bubbles. The master-cylinder reservoir confirmed that we were sending fluid (it went down each time)...we thought all was great.

We jacked the rear-end up and spun each wheel, hit the brakes...no grab. Adjusted the brakes to be really conservative...still no stopping power to the rears. How strange: fluid is bleeding (albeit a little at a time) and no air in the system (from what we can tell) but no stopping power.

Some odd observations: The pedal seems to have 2 halves; 1st half (top-half) drives the rears alone, 2nd half drives the fronts. Is this normal?

How we realized this was, the pin on the prop-valve only pops out AFTER the 1st half of the pedal is depressed...not before. This is actually how we got the rears to get fluid...initially we were giving full pedal depressions, and the pin would shoot out, and no fluid to the rears. We also channel-locked the pin in place (kept it from jutting out) and with full pedal depressions, no fluid. Wasn't until we just did 1st-half of the pedal depressions that anything went back there (again, only a small amount per press...but got bled out nicely).

We also noted that the master-cylinder wasn't contributing fluid to the rears (reservoir stayed the same) when we were trying full-pedal depressions.

Now with the whole system bled, we're getting the pin popping out when we brake fully-depressed, fronts stop beautifully, and no power to rears.

grrr.... ideas?

Thanks ~Jon
__________________
[B]Can't get away from these things[/B]
85 CJ7 Frame up Restoration in progress
Jonnyhaku is offline   Reply With Quote
Unread 10-27-2008, 05:14 PM   #11
dalefan388
Registered User
1979 CJ5 
 
Join Date: Aug 2008
Location: ada, oh
Posts: 103
i bought a new ms and it was bad out of the box. got the second one and now its fine. where did you get the ms.
dalefan388 is offline   Reply With Quote
Unread 10-27-2008, 10:04 PM   #12
Jonnyhaku
Registered User
 
Join Date: Jan 2005
Location: Washington Township, NJ
Posts: 36
got the ms at advance auto. Think it could be that?
__________________
[B]Can't get away from these things[/B]
85 CJ7 Frame up Restoration in progress
Jonnyhaku is offline   Reply With Quote
Unread 10-29-2008, 04:56 PM   #13
dalefan388
Registered User
1979 CJ5 
 
Join Date: Aug 2008
Location: ada, oh
Posts: 103
i work at advance auto. we have had some problems with reman ms lately. thats why i changed mine as soon as i had a problem
dalefan388 is offline   Reply With Quote
Unread 01-06-2014, 07:55 PM   #14
RustBkt
Registered User
1995 YJ Wrangler 
 
Join Date: Dec 2013
Location: , NC
Posts: 4
Calipers are on wrong side

I agree with the post that says the calipers are installed on the wrong sides. It's cheaper and faster if you check that first. Bleed screws should be on top of reservoir not on bottom. Whoever stated this solution first is a genius!
RustBkt is offline   Reply With Quote
Unread 01-07-2014, 03:11 AM   #15
John Strenk
Moderator
 
John Strenk's Avatar
1976 CJ5 
 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 13,007
Did you wan't to post here???
This is about 4 years old.

were you looking for another post??
John Strenk 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.