Brake pedal to the floor (again)

[Flicktitty]

So i did a Q45 brake swap on the S13 coupe over winter, Noticed it was leaking fluid from the caliper, So i replaced the caliper and didn't see any more leaks. Bleed the brakes pedal was good as new. then i noticed the reservoir was going down without using the brakes (just sitting in the garage) I I went back through didn't see any leaks so i assumed with the new Q45 stuff it might have killed the BMC. So i replaced that. bleed the brakes. pedal was fine. Went around the block car was good. parked it and then loaded it onto a trailer took it to get dynoed, now the pedal just goes to the floor.

Run down of parts-
Stainless steel lines.
1 Refurbished Q45 Caliper
1 Used Q45 Caliper
"cheap" temporary brake pads
Sentra SE-R EBC Rotors
DOT4 Brake Fluid
Refurbished BMC

So most of the parts have been replaced on the front, i'm still not seeing any leaks, I Suppose the used caliper could be bad, or maybe something with the rear? Any ideas?

[Sileighty_85]

Did you bench Bleed the MC?

[Flicktitty]

Did you bench Bleed the MC?

Yessur i did, Did it till there was no visible air coming out then bleed all 4 brakes. Pedal was fine for a few weeks just sitting, then it went to the floor after a few times pressing it.

[rwtf]

got a leak somewhere.

[PureRush]

Yeah you have a leak somewhere. Take off all the calipers and check for brake fluid and check the lines. If there's no visible leaks then it's an internal problem in your BMC