OT disappearing brake fluid

Took a day of vacation and before I got out of bed, the DIL called and said she had brake problems. The light was on and she didn't have any brakes. She drove to our place and borrowed the wife's car to go to work. The reservoir was down enough to trigger the warning light. I got under it and did not find fluid coming out of either rear brake drum and there was no fluid visible on or around the front discs. I followed the brake lines from the rear forward and from the master cylinder back to each wheel. I drove it and it worked normally.
Where else could it go? Is it possible that it could be going into the power booster and into the engine? Thanks for making you think!
Roy

pull the vaccuum line going to the brake booster at the booster and check for fluid. its either going there or recheck your rear wheel cylinders.

the inside of the hoses could be bad too theres a lining in there that gets a hole in it then all of a sudden theres more space to fill so level goes down if its that pretty soon she will have a brake hung up cuz the fluid goes in but not back out

glenster is right if its not leaking it, its burning it in the engine by sucking it thru the booster and into the hose, only other thing is very rarely when some vehicles get criticly worn front pads the fluid can get low enough to turn the light on, but its rare and by that time half the front brake componets are trashed [ rotors and calipers] and there is noise from everything,

I pretty much agree with Glen. One way to maybe find out for sure is this. Fire it up and then hold down hard on the brake pedal and hold for as long as you can or till the pedal drops. I have run into that problem before and the master cylinder is going bad

A low master cylinder doesn't necessairly mean it's losing fluid. Low fluid level could be caused by pad wear. Some vehicles can leak through the secondary seal at the rear of the master cylinder into the booster. Some Caravans did that. Just pull off the master cylinder and look at the rear of it for leakage. Don't just look at the drum for signs of leakage, pull the drum and inspect it to make sure. Brakes are just too important. Hope this helps. Gerard

I"d say if this was the 1st time the light has come on and no fluid has been added. All the pads are worn thin and all the fluid is in the calipers.

master cylennder could be the culperet here, the brake fluid may be leaking out of the back of the master cylender and be getting soaked up by the carpet look under the dash and seee if its damp there

Most likely that the pads/shoes are just worn out and the pistons are fully extended. If you add fluid and it doesn't lose any more it's probably safe to assume that the brakes are about worn out. If it continues to lose fluid then you have a leak somewhere...

Rod

If the reservoir was bone dry and no brakes that would bother me... I take it it had fluid but just a little low... You said she said she lost her brakes but it has fluid in the reservoir... I am think'n the master is leak'n by,,, maybe even another problem,,, it best you have it checked,,, good brakes are hard to beat.... and the no brake complaint needs to be investigated... and yes its possible to loose the brakes and have fluid in the reservoir...

Back to the master,,, sometimes its hard to duplicate one that's fail'n... If I doubt one I shoot it, shin it and mount it.... every mechanic has their routine that they go thru to test for a leaker,,, not gonna go into that as they vary,,, I had a Nissan pathfinder that was loosing fluid,,, looked it over and no leaks so condemned the master,,, ordered up a new'n,,, removed the old one,,, 2 my surprise it was not leak'n out the back of the master so went hunt'n again,,, I found the leak at the lode compensator valve that's located just above the rear axle,,, had to eat some crow,,, I missed the leak on my initial check... I also remember the first low/no brake complaint I had that turned out to B a bad wheel bearing :evil:

As some others have said,,, its normal for the fluid to disappear """OVER TIME""" as the pads ware... Its the nature of the beast and a good indicator to check pad ware....

Yep , agreed , similar to the Hydravac is sucking in Brake Fluid on my 1975 Ford grain Truck ,.every 3rd load to town I need to add less than a quarter cup .. But i always fear that thingwill open Up and Suck it dry

On some makes, the fluid reservoir light is intended to indicate when the front brake pads need replacing. I've never run across a vehicle with a reservoir indicator; I think this is peculiar to certain Japanese makes.

Thanks for all the replies.
I should have driven it more than I did before I proceeded to fix it. The ABS light was on when I drove it, but I would expect that. That was the only brake light that I saw. The brakes seemed ok, but I was treating them gently. I should ad that the report came from from a young blond woman early in the morning. I will keep an eye on the situation and see if it repeats or the brake pads start making noise.

I've noticed there are some female drivers with a heavy right foot on the gas pedal also end up with a heavy right foot on the brakes. 35,000 to 50,000 is all they can get out of front brakes. I can get better that 80,000 miles. My daughter goes through the front brakes.

Merkur XR4TI had that. So Germans do it also.