brake master cyl?

[sjp88grndwagon]

Just one more thing than I am sure needs to be fixed. Deperessed the brake pedel this am when warming up and it stayed pressed, with brakes engaged? Master cyl shot? After warming up, restarted the jeep and bakes were fine? Any ideas?

[RWalker]

Probably a bad master cylinder. Has it been leaking at all? Check for leaks at the bottom of the black housing of the master cylinder and on the inside of the truck where the rod from the master cylinder comes through the firewall.
Richard
88 GW

[sjp88grndwagon]

I have not seen any leaks, but I will take a closer look. What role does the booster play? how can I check that?

[RWalker]

The brake booster is just a diaphram that uses the engine vacuum to increase the pressure that you apply to the master cylinder when you depress the brake pedal. Do you ever have to pump the brakes to get a stiff pedal when trying to stop? If you do then you've got a leak somewhere or air in the lines. Check the rear brake cylinders for leaks too.

[sjp88grndwagon]

I do have to pump my breaks to get good responce from the pedal. So is it just the diaphram that go or can it be engine vacuum problems that prevent the booster from working?

[Mud Thrasher]

Your booster isnt the problem. If it were bad then you would hear a hissing sound when you press the brakes. You could have air in the brake lines or have a leak. A lot of times when the master cylinder goes it will leak where it bolts to the brake booster. It's under the hood on the drivers side. If you look at the brake booster if you see where it looks like fluid ran down it then the master cyl. is bad. If you dont find a leak i would first try to bleed the brakes first and then go from there.

[RWalker]

More than likely your booster is working. It wouldnt cause the problems you are describing. If you dont see any leaks then bleed the lines. More than likely you've got a leak somewhere though.

[sjp88grndwagon]

thanks guys, didnt want to seem stupid, just wasnt sure what is what. Thanks, this will give me a place to work from

[goofy289]

my master cylander did the same thing awhile back.unfortunately i was 50 miles from home,towing my fishin' boat!took alot of downshifting to get it home.but about halfway it started working fine again. 2 weeks later,same thing.so i replaced m/cylander and no mo problems :cool:

[sjp88grndwagon]

Well good news, I found a leak in my brake line, the long one going to the back. So that is mush better than the booster or master. Thanks guys for the help!!!

[oldyeller]

If your master cyl. or brake lines were leaking would you see brake fluid? kinda stupid ? but when I went for inspection they told me that i had a leak in my master cylinder and my brake lines, but the master cylinder is full. I cannot see any wet spots around the master cylinder or the brake lines. Coukld i just have air in the system? When i push the brake pedal while the truck is running, i cannot get a solid pedal when i pump it, i can when the truck is not running though.

[ February 10, 2003, 07:12 AM: Message edited by: oldyeller ]

[64Trvlr]

Originally posted by oldyeller:
If your master cyl. or brake lines were leaking would you see brake fluid? The master cyl can bypass fluid internally. When that happens the brakes don't work very well if at all but there is no external clue it's bypassing.
:cool: