79 CJ7 Break Problem Question????

[Tug-n-pull]

Hey,jeepz.com is the 422,500

When to the woods in my CJ7 with power and disc breaks on front. After a rough section of trail I went for the breaks and the pedal went to the floor. Master Cyl. was very low on fluid. I was able to pump em up and they worked but went soft right away. I feeled up the master and it seemed ok not leaking down. I bleed the breaks all away around and the pedal felt good, let it set a few mins and down they went again. Now if you are rolling slow and apply the breaks you get a growl every half turn in the driver side front hub area. Just have not had the time ot get in there but think it may be a front calaper gone bad. Any ideas. tug

 

[firemanharry]

Can you still pump it back up?

Does it slowly fade if you leave your foot on the pedal after pump-up?

Are you still losing fluid?


:?: :?: :?: :?: :?: :?:

 

[far_right]

it sounds as if you need a new master... thats what mine did... but i also didnt have power brakes

 

[jeepin916]

painting the headlight housing...

im not sure about the losing brake pressure other than your vaccum booster, or master, but if your making a growel noise every half a turn i would check the brake pades and rotor, you could have warped the rotor and its not flat, or you might have a high spot and its rubing the brake pades, also makesure nothing under there is bent and just rubing when u are rolling.

 

[Inspector-Gadget]

Hi Tug,

The brake fluid had to go somewhere. I would look first to see which wheel/tire is wet on the inner side and reeks of the distinctive odor of brake fluid.

You didn't mention which of the two master cylinder reservoirs was low on brake fluid -- perhaps they were both low. On my power-brake equipped CJ, the front M-C reservoir is for the rear brakes. The much larger rear M-C reservoir is for the front brakes. If only one reservoir was low, that is a clue as regards which of the two brake systems might be leaking.

HTH

Regards,

Gadget

PS: Isn't there an unusual sequence in which the brakes need to be bled because of the proportioning valve? Some factoid about that is stuck in the dark recesses of what passes for my brain.

 

[Tug-n-pull]

Sorry folks I was half asleep and very vague in my post.

It is the front compartment of the reservoirs that was low as in nearly empty. Back was full. I did the bleed furtherest wheel from the master first. So I did the passenger side rea first the the other pasenger side front and so on. No wet spots to find unless it is the wheel no smell untill I bleed them all. I will pull the wheels tomorow or raterh tuesday. Hopeing it is not the master / booster cause that is going to be costly I am sure.

As for the loss of presure no if you pump it up and hold it it holds pressure very nicely. It looses when it is setting with no pedal presure at all. Jeeps sheeeezz what a beast. tug

 

[avyoung]

I had a pin hole in a mustang that did basically the same thing once it got low on fluid. Have someone pump the brakes and look for brake fluid.

 

[L33TJ33P]

We've done that. We even parked her on the Dry road and pumped the brakes to look for any leaks. What is tricky is that, sometimes his Front res will be lower and sometimes the Rear res. Very odd indeed.

 

[Bounty__Hunter]

The resevoir nearest the front of the jeep is the rear brakes, sounds like a rear wheel cylinder gone bad. Pull the drums and you'll likely see the leak.

 

[BakedAlaskan]

Yup it's in the rear brakes unless it's leaking down the firewall?? But I bet like Bounty saud it's your rear cylinder or hoses.

Don't fret they don't make an expensive part on our 79 brake system.

 

[bksmith]

Inspector-Gadget - yes there is a proper way to bleed the brakes, starting with the pass. side rear then driver side rear, then pass side front and driver side front

 

[firemanharry]

The line feeding the rear brakes drops down on the passenger side and then goes over to the Driver's side. This would make the Driver's side farther from the master cylinder. That's the way I see it.

 

[Inspector-Gadget]

I am uncertain of the relevance of what follows as regards Tug's CJ brake system problem, but in the many posts which I have read on the subject of CJ brake bleeding, rarely have I seen mention of the proportioning valve. Should this post should prove useless to Tug, perhaps it will be useful to someone attempting a CJ brake bleed in the future.

Inspector-Gadget wrote:

PS: Isn't there an unusual sequence in which the brakes need to be bled because of the proportioning valve? Some factoid about that is stuck in the dark recesses of what passes for my brain.

Bksmith wrote:

Inspector-Gadget - yes there is a proper way to bleed the brakes, starting with the pass. side rear then driver side rear, then pass side front and driver side front

Firemanharry wrote:

The line feeding the rear brakes drops down on the passenger side and then goes over to the Driver's side. This would make the Driver's side farther from the master cylinder. That's the way I see it.

Bksmith and Firemanharry: I believe you are both correct about the sequence of brake bleeding. The usual sequence is to begin with the longest brake line run and end with the shortest brake line run in the sequence of a four-wheel brake system air bleed. The typical sequence would be RR-LR-RF-LF, but that might not be true for all vehicles -- depends on the configuration of the plumbing.

My "PS" quoted above, was very poorly stated. My "PS" should have read: Isn't there an additional step required when bleeding a CJ braking system. There is an additional step. A look into my Jeep service manuals revealed the factoid I could not earlier recall. Per the service manuals, the proportioning valve (P-V) metering valve stem is supposed to be depressed during a four-wheel brake bleed.

The diagram immediately below shows the "innards" of a brake system P-V. The P-V is really two valves and an electrical switch in a common housing.

In the diagram the metering valve system is boxed in blue. The metering valve stem which must be depressed is at the left and within the boot. The special tools available to hold the metering valve plunger depressed during a brake system bleed are shown in the second illustration, below. It would seem those tools could be easily fabricated.

Regards,

Gadget

 

[Tug-n-pull]

Turns out to be a passenger side front caliper is blown out. Caught the problem so quick that I just now pumped enough fluid through the thing to find the leak. This is an ez fix and now let get on with the show. Thanks for all the in put. tug :wink: