My 123 has a brake fluid leak somewhere that I can't seem to find. The brakes themselves work perfectly but I lose an ounce or so of brake fluid a week. A visual inspection of the calipers showed no sign of leaks. Yesterday I hooked up my EZ Bleed and pressurized the fluid resevoir to about 30psi but still saw no signs of leaking (nor did it seem to produce any fluid loss either). I'm reluctant to take the pressure up much higher. At my last brake job the outboard piston on my left front caliper was a bit stiff when I tried to press it back in for the new pads so I thought that might have a slight leak but upon close examination it seemed dry and tight. I've heard stories of master cylinders leaking into the boosters but am not sure how to check for that. I did look up under the brake pedal for signs of a leak on the inside of the firewall but it too was dry. All the steel brake lines appear to be in good shape. This is a longtime dry weather car so rusted lines is definitely not the problem. Anyone got any good ideas?

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold