What shape are your pads in? If they are worn out, the caliper pistons will require more fluid to make up for the increased travel. You may have gotten some air into the system. Three likely causes, air in the system. leaking brake line somewhere, master cylinder is heading south. If it's the MC replace it. Not worth the trouble and expense of rebuilding, and.. with the brakes, don't mess around with a major safety issue. Be safe, fix it right. The life you save may be your own or someone you love. Cost about $105 here at Parts Shop (cheap insurance)..

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.