i'm wondering if someone can help diagnose the source of the problem i'm having.
over the past week, i tore my bike down to the frame and have been replacing everything except the derailleurs and brakes. i decided to do a brake bleed (hope mono m4's); i've never done one before.
i made some mistakes but wound up figuring it out and getting into a rhythm. i'm certain i did it right, except i've got one issue: when i squeeze the front brake lever, a little brake fluid comes out of one corner of the reservoir (one of the corners without screws). the harder i squeeze, the more fluid comes out -- and if the lever remains squeezed, the fluid keeps trickling. it's not much, but it's enough to drip on the ground.
here's what i've checked:
1) reservoir bolts are tight.
2) the rear brake is working perfectly, so i know i'm capable of a proper bleed.
3) i repeated the whole bleed on the front, to eliminate a fluke chance of having done something wrong.
4) i swapped diaphragms from front to rear. no change: the front leaked, while the rear didn't.
5) i then swapped reservoir caps from front to rear. now diaphragm + cap from the front were on the rear lever. BOTH sides leaked (notably, from the same corner -- the near left corner if sitting on the bike.)
6) i swapped diaphragm + cap from rear back to front. the problem went away in the rear brake and returned in the left.
i did not try just a swap of caps.
what puzzles me is how both brakes leaked with a swap of caps. i'm also puzzled as to how a cap could go bad. i don't think i did anything wrong.
is it more likely to be the diaphragm? these are approximately 5 years old. if it's the diaphragm, why didn't the problem switch levers when i swapped diaphragm?
the diaphragms can only be installed one way, so i know i didn't screw that up.
i see them online for $8 or so (seems high), but i don't want to order + pay for rush shipping only to figure out it's a cap or reservoir issue. if it's the reservoir, does that mean i need a new lever?
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