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Discussion Starter #1
Driving into work today (cuz it's been raining hard in Tucson, I usually ride my motorcycle) and hit the brakes kinda hard, heard a pop, and the big red Brake warning light in the dash came on. Won't go away. Brakes seem a little worse than before, but still ok. I checked the fluid in the master cylinder and the big reservoir is full, but the little one in front is empty. Does that mean there's a leak in the rear brake circuit?
 

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I scrape on both sides
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put fluid in, give it a couple pumps and check for leaks
 

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Well top it off and see how it drives just a short distance to see how the pedal reacts....though you may have sucked in air in the small part of the reservoir due to the low fluid, hopefully the master cylinder isn't fubar....so re-bleeding might be in order.

I would also visually inspect front flex lines, fittings, calipers, non adjustable proportioning valve usually located directly below the brake booster near the frame rail where the brake lines converge coming up to the master cylinder and look for fliud leaks.

Check the rear backing plate to axle side underneath where the adjustment slot is to see if there is a fluid leak, wheel cylinder/s will bleed out that side so you'd have to pull off the drum/s and make repairs, replace both wheel cylinder/s if the seal/s are gone....PITA tear down job but wheel cylinders are not expensive so get a good quality brands.

With the drum/s off, check each backing plate "bolts" (4) to axle and make sure they're torqued correctly, not loose otherwise when you brake backwards/forwards the backing plate will "ratchet" causing the brakes to lock up with the slightest touch on the pedal and possibly snap/shear off a bolt and really be in the shite not too mention the carnage inside.

If for some reason you dodged the bullit with low fluid in the reservoir and the pedal comes back, adjust the rear brakes by expanding the shoes out until you can't turn the wheel then retract the shoes until you hear/feel a slight "drag" from shoe to drum. I lift the BKO from the center off the differential on a level floor so it won't go anywhere, using a floor jack lift just enough to get the wheels off the floor a couple of inches max, key on in neutral with parking brake off you should be good to go.

Let us know what you discover!

Good Luck ~ :thumbup
 

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Discussion Starter #5
Thanks, all. I'll check it out this weekend and keep you posted. :beer
 

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Any trouble with the "star" adjustable key/s inside, the Haynes Manual, Chptr 9, has an illustration showing you can stick a screw driver in the adjustment "slot" pushing/lifting the self adjust lever away from the key so it turns easier using the brake spoon.

Just a thought!

Good Luck ~ :thumbup
 

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Agreed, reservoirs don't empty out on their own, you have a leak - if you heard a pop, I'm guessing you've lost a cylinder too. Easy fix at least.
 

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Discussion Starter #11
So I topped up the fluid and all is well. Brake pedal feel is great, as is the braking. It was the front reservoir (the smaller of the 2 which is for the front discs, right?) that was low. Is it normal to consume a bit of brake fluid over the years? I've got some big heavy wheels and tires on, I can see the brake system works very hard. Wondering whether some of it boils off from time to time or something, or whether I should look closer for a leak. I wasn't able to see any leaks from either brake, front or back.
 

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I've got a '96 BKO and noticed a brake fluid leak coming down from the backer plate of the passenger rear drum this weekend while doing exhaust work. Then I was an idiot by not checking it after finishing the exhaust. Today I noticed some pedal fade and checked the reservoir...empty. Now I'm at work 30 mins from home. Is the cylinder the most likely cause of this so I can pick up some parts today before I head home? Is there anything else I should get just in case and return if I don't need it? Not wanting to run around to much and needing the parts today can I count on Advance Auto or Autozone cylinders?
 
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