Brake fluid vanishing?

I have an 08 dodge caravan. one day, the brake light came on and I put fluid in it. several weeks later, to a month it happened again. Ever since then, I have been looking for a leak. ( about two months now). the level at which the fluid comes out has been progressing. the most it was, about once a week I had to top it up ( from me filling it to when the light came on)

At this point, I had just filled it 2 days ago. Drove it yesterday, ( nothing abormal, everyday round trip type of deal). It was quite full at this point. when i got home, the brake light wasn’t on and everything was fine. I wake up the next morning, put the car in drive, boom, brake pedal hits the floor with no resistance at all. the reservoir was completely empty.

I have found what i think is a tiny bit of brake fluid under the rear passenger tire area, but it’s random and not consistent. i’ve been noticing it about once every week or so, the issue is it’s near the exhaust so it’s hard to discern. Getting in the car and pumping the brakes yields no visible leaks anywhere. Not a drop, spray, nothing and the fluid doesn’t seem to leak. It always seems to happen when it is sitting overnight, not when I’m driving it.

So far, I have put in over 2 big jugs to keep this thing working over the last 2 months, the first jug lasted about 5 weeks, the 2nd 3 weeks.

With this amount of fluid, I would surely see a puddle somewhere, or something right?

This is my only vehicle and every time I have had a brake issue, it’s been a rusted out line, fitting, hose, or caliper. I’m just not seeing a thing with this one.

Any Advice?

Topic

[micah russellParticipant]

I wanted to add, this morning when it emptied completely out, once refilled the rear brakes still worked- the front did not function at all until the brake pedal was pumped at least 10 times or so. It had just sleeted/snowed here, so it was very obvious. After some pumping, the front started to work again.

Obviously I know the system now needs bleed as well, however, it may be some sort of symptom I am unaware of.

[Richard KirshyParticipant]

My first suggestion would be to remove all 4 wheels and inspect the calipers (and wheel cylinders if so equipped) for signs of fluid leaking.
If everything checks out ok then remove the brake booster hose from the brake booster and see if there is fluid inside the hose.

[micah russellParticipant]

That’s an excellent Idea, I’ll do that. I did go ahead and check the booster hose and removed the master, no fluid in there at all.

Now to check all the wheel cylinders once my fingers have feeling again.

[micah russellParticipant]

It was the rear passenger wheel cylinder, leaking from the piston for some reason. It looks like it dripped on the rim, and spun around and slung it everywhere instead of leaving any sort of puddle. Still insane this leaked out all the fluid overnight and didn’t leave a puddle.

Anyway, Thank you!

[Author]

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