It is possible for a piece of the inner rubber lining in a brake hose to pull away and act as a "flap" valve. This can happen in older brake hoses and result in either pressure not getting to a caliper or pressure not being released from an engaged caliper - depending on how the lining peels away. That is one reason why all rubber brake hoses should be replaced on older cars as a normal safety item. One long-time Mercedes mechanic said he found the O.E. hoses on benzes were good for 20, or so, years. Many have been left on much longer than that w/o trouble but should be replaced. Think about all that flexing going on over the years.

The main reason brake hoses do not release after pedal application is they are constricted from swelling inside. When one applies the brake ,the Master has a great enough pressure force to flow thru the constriction, but when released , the only force to return/release the calipers is Residual pressure ..much less than pedal pressure...resulting in a hanging brake pad.
An easy test for this condition is to jack each wheel , apply the pedal force , and then hand turn that wheel..if wheel is locked [or excessive drag]. open bleeder ..if the wheel then frees , you have a bad hose. if it doesn't , you have stuck caliper.

__________________
A Dalton

Nice trick, Arthur.....

__________________
-tp


1990 300SE "Corinne"- 145k daily driver - street modified differential - PARTING OUT OR SELLING SOON - PORTLAND OR. AREA - PM ME FOR DETAILS
1988 560SEL "Gunther"- 190K passes anything except a gas station
1997 S420 - 265k just bought it with a rebuilt trans. Lovely condition