Disappearing Brake fluid... need some help

[1997XLTRollover]

Hey all. My 96 again. Big surprise. I recently noticed that I have been slowly losing brake fluid and I can't find where the heck it's going; the master is low but I see no leaks. All my rubber brake hoses and all hard lines are brand new (read not original and not rusted and replaced within 2 years). I looked over all the lines and see no leaks. Caliper bleeders look fine and I see nothing dripping from under the abs or master cylinder and of course no leaks on the ground.

So I figured ok here we go, rear master cylinder seal blew. So I pulled the master off the brake booster and I don't see any fluid behind the master cylinder. The only thing I could think of it's leaking internally to the ABS pump. Is this even possible? Thoughts?

 

[SupaSwope]

Your fluid level naturally goes does down as you use your brakes and the pads become thinner more fluid stays in the lines. If your not seeing leaks that would be my guess, But that depends how much fluid your loosing.

 

[1997XLTRollover]

Your fluid level naturally goes does down as you use your brakes and the pads become thinner more fluid stays in the lines. If your not seeing leaks that would be my guess, But that depends how much fluid your loosing.

Good thought and although that's true, I haven't tracked my explorer recently so I haven't worn the pads much lol. In all seriousness it's dumping id say 1/8th-1/4 of the master cylinders level in around 500 miles.

 

[J_C]

Had you checked it previously, besides just after the brake work, so you're stating it is gradually continuing to lose more fluid, or is there the possibility that there was air in the lines that worked itself out?

For now I'd just top it off and see if it continues to go down.

 

[1997XLTRollover]

I haven't done brake work in 2-3 years and around 10k miles. No I haven't driven this truck much, its been broken more than it has been running. But yes I've already topped it off. It's losing 1/8-1/4 of the master in 500 miles.

EDIT: Maybe it's more like 1/8 of the master. 1/4 is a lot. It's not going away crazy fast, but it's consistently dropping.

 

[J_C]

I suppose there might be some kind of UV dye you could put in, then wait and check for leaks with a UV flashlight... though I'd think it should stay wet so that isn't necessary.

 

[1997XLTRollover]

I suppose there might be some kind of UV dye you could put in, then wait and check for leaks with a UV flashlight... though I'd think it should stay wet so that isn't necessary.

I was thinking that. Time to do a google search for UV brake dye. Problem is it doesn't circulate well so I don't know how well that would work. Especially if it's internal to the abs pump. Actually I wonder if brake fluid glows under black light on its own.

 

[SWIGIN]

I had this problem with my 79 bronco. Turns out after filling the MC every 2 weeks for a year the problem finally showed it's ugly face.

The hard line that runs back the frame to the rear brakes was leaking. Not in one spot but the whole thing was weeping along the entire length never making a wet spot or puddle to see.

When I went to tear the old line out it literally fell apart in my hand like a tube of nothing but rust.

 

[1997XLTRollover]

I had this problem with my 79 bronco. Turns out after filling the MC every 2 weeks for a year the problem finally showed it's ugly face.

The hard line that runs back the frame to the rear brakes was leaking. Not in one spot but the whole thing was weeping along the entire length never making a wet spot or puddle to see.

When I went to tear the old line out it literally fell apart in my hand like a tube of nothing but rust.

Mines all completely brand new so unfortunately that's not my issue.

 

[J_C]

Well you can only lose so much of it before it HAS to leak somewhere, right?

 

[SWIGIN]

You would think but like I said above it took mine a year to show me anything.

 

[1997XLTRollover]

Well you can only lose so much of it before it HAS to leak somewhere, right?

One would think lol. If it's not internal to the abs module, the only thing I can think of are my stainless braided lines because I did have to reuse a small part of those. But I looked them over and didn't see anything.

 

[1997XLTRollover]

You would think but like I said above it took mine a year to show me anything.

It also doesn't help that it's the middle of sloppy winter here in nj and my truck is covered in all sorts of crap. So maybe it's just hard to see right now.