Brake Fluid keeps becoming low in Master Cylinder

stainlesself

stainlesself

New member
Hey all, before I post my issue I just want to say thanks for everyone who has helped me on previous forum posts and discussions love the community on here.
Now to the issue, my JKU is experiencing some loss of brake fluid in the master cylinder enough to cause the BRAKE light to come on every so often. However, I have checked all the calipers and brake lines for signs of leakage nothing.
Also, my pads and rotors, and calipers had been replaced 2,000 miles ago by a shop. Not sure why fluid keeps leaving the master cylinder. Furthermore, when I pushed down on the brake peddle yesterday pedal went all the way to the floor for the first time and felt very spongy, then got firm again for the rest of the drive.
Any input and suggestions are appreciated thank you!
 
Check the gasket for the cap on the MC. Also check that the cap is seated correctly and the spring seals it.

Then check all the line connections at the MC.

If you still don't find anything, time to run the lines looking for holes, splits. Check any rubber sections for dry rotting and cracking splitting.

Brakes be fun 😐
 
kevman65 said:
Check the gasket for the cap on the MC. Also check that the cap is seated correctly and the spring seals it.

Then check all the line connections at the MC.

If you still don't find anything, time to run the lines looking for holes, splits. Check any rubber sections for dry rotting and cracking splitting.

Brakes be fun 😐
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Could air also have gotten in the system from an incorrect bleed of the brakes?
 
Yes, and eventually most of it will work it's way back to the MC. But by your description of the amount of fluid you're replacing, you have an issue somewhere.
 
Disconnect the master cylinder from the brake booster. Should be two nuts and you do not have to disconnect any lines. See if rear seal is leaking fluid into the booster. You can use a zip tie as a dipstick to see if fluid is getting in there. Not really a common thing on Jeeps but very common on GMs.

Once master cylinder is loose, try not to disturb the rod inside the booster. Some of them are adjustable.
 
Is the Jeep an automatic or manual? The clutch system shares with the break reservoir on JKs. Just another place to look if it’s a manual.
 
WJCO said:
Disconnect the master cylinder from the brake booster. Should be two nuts and you do not have to disconnect any lines. See if rear seal is leaking fluid into the booster. You can use a zip tie as a dipstick to see if fluid is getting in there. Not really a common thing on Jeeps but very common on GMs.

Once master cylinder is loose, try not to disturb the rod inside the booster. Some of them are adjustable.
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Ths^^ seen many master cylinders fail and leak into the booster and not show sins of hitting the ground
 
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