95 brake reservoir ran bone dry!? Bleed like usual or more?

My girlfriend took my 95 Riviera to town today. She called me and said "the ABS light is on". This light has been on, I had a wheel bearing changed a while back and was pretty certain the other one was on its way out.

Well apparently something else was going on. She brought it home and it has no brake fluid whatsoever. It took a LOT of fluid to refill it, and of course I now have zero pedal (but the ABS light is off now!).

The car has four wheel disc, I can't see any leaks anywhere. The pedal has no effort at all, you could push it down with a feather so I'm assuming the booster is still ok.

Can I just bleed this master cylinder and brakes and be ok, or is there something else I have to deal with concerning the ABS? Also where on earth has my fluid gone!??! I can't see any leaks anywhere and there wasn't any in the spot it was parked.

Bleeding them should restore the pedal feel but you have a leak somewhere. maybe the MC is leaking or one of the lines going to the ABS pump. after getting the air out you should be able to spot the leak/drip easier.
She should NOT drive the car because without fluid there are no brakes.

My guess is the system just ran dry.it happens.BF leaks are So noticable.If you have doubts just fill the reservoir and watch for leaks.If none,you will have to refill and complete a break bleed procedure.Fill reservoir with fluid.During procedure keep eye on level.With helper.Have helper pump pedal a few times to build pressure then press pedal down all the way and hold.crack the bleeder screw on the front driver side,watch fluid run out,tighten bleeder,tell helper to release pedal. Now move your way to passenger side rear and repeat procedure. Then move to front passenger side and then rear driver side. As far as I know its the best way to bleed ABS system.
This will address a possible air in system situation.Only way to be sure.

p.s
never loan a Riviera to a GF. very few women can handle such a prime vehicle(Florence X was the only exception to the rule)
peace out
R

There's a leak somewhere. Brake fluid doesn't evaporate, so it can't just run dry. Level can go down a little when pads/rotors wear, but it's only a small amount. When you replace these parts, fluid will come right back up. If you're all the way empty, there's a serious leak somewhere that needs to be found. Since you'll need to bleed them anyhow, it will probably be seen under the car while pumping. If not suspect the MC is leaking into the brake booster.

AA wrote:

There's a leak somewhere. Brake fluid doesn't evaporate, so it can't just run dry. Level can go down a little when pads/rotors wear, but it's only a small amount. When you replace these parts, fluid will come right back up. If you're all the way empty, there's a serious leak somewhere that needs to be found. Since you'll need to bleed them anyhow, it will probably be seen under the car while pumping. If not suspect the MC is leaking into the brake booster.

I agree, you're off the road until you find that leak. To find it:

- look for a wet caliper.
- put fluid into the system and pump on the brakes while looking for fluid spraying from a pinhole leak in a line or at a wheel cylinder. This could go un-noticed because if it's spraying onto the road you won't have evidence on the car.

However...

The HINT is the system appears completely dry.

So... this is most likely a leak from the master cylinder into the brake booster. Effective fix is to get a booster and cylinder from a junkyard - a bunch of BOC cars used the same setup at the Riv. Pretty much any JY near you that pulls and inventories parts (not a pick-and-pull) will have or can get you one no prob. Bench bleed and install it and you'll be back in business.

For my money I'd replace the MC every 150,000 miles, more or less, whether needed or not... along with all the soft lines. If the booster never gets wet it may never wear out.

Albertj