[pippintook]

I'm helping my brother fix my my mum's 2005 honda civic. About 2 months ago, my mum was having bad bad braking. She didn't call me but went to a local auto chain store and kid said she had no fluid in brake reservoir. He filled up brake brake reservoir. She said it braking was better. I told her bring car to my place and we would check it out. She came by few days later. I crawled under car and tried to look at all lines and could not find any leaks or signs of leaks. The brake reservoir was full. I drove the car and the brakes were definitely a little bit spongy. I said lets monitor and see if it loses more fluid. I checked the car about a week later and fluid level was still the same.
Brakes were still spongy. I thought possibly the master cylinder had somehow got empty and air got into system. I thought maybe do a full
bleed - though I did not do the bleed
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Over the last 4-5 weeks she has not been using the car too much. A few days ago she said braking was getting really bad. My brother drove car and told me brakes were really bad. Very spongy and had to have pedal almost on the floor to stop. He brought the car out to my place. We could not find any leaks and brake reservoir was full. I drove car and brakes were really bad - almost undriveable. He thought the master cylinder had failed. So, we agreed try new one. We installed new master cylinder. We bench bleed it before install. After installing, I went to each wheel while he pumped and we bleed the brake system. Fronts had good flow and some air came out. Back right rear did not have any flow at first when I loosened the bleeder and he pumped. Eventually, it flowed and seemed to generate a moderate stream of fluid from bleeder with no air. I started doing the left rear, got fluid and after some pumps - decent stream with no air. Then, i noticed small brake puddle by right rear. I went back to right rear and he pumped. Now, I saw small tiny stream of fluid come from brake line near wheel cylinder (car has drum brakes in back). There is an approx. 8" steel line from rubber flex hose to wheel cylinder - this line had tiny leak.
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I bent up some new line and replaced. All good - no leaks. We then bleed all wheels. But, we could not really get the brake system to firm up - the brake pedal felt spongy. We first tried manual bleeding at each wheel - each wheel would show maybe a little air bubbles and then good stream with no air. Brakes still felt spongy. I tried my automatic bleeding with harbor freight tool that uses air compressor and sucks fluid out. This also seemed to work pretty good and showed good stream of fluid with no air bubbles - but brake pedal still spongy. We tried bleeding with engine running- manual and automatic bleeding and brakes were still spongy. We thought maybe air trapped in master cylinder , we bleed master cylinder on car but brakes still spongy.
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The car has ABS - we thought maybe some air trapped near in ABS module. He pumped the brakes and held them. The two lines from master cylinder
go into the abs module. When I loosened what is the rear line from MC - i get nice stream of fluid coming out near threads. He pumped brakes again and I loosened what is the front line from MC - i get weak stream of fluid - the fluid just kinda trickles out on the threads. Not sure if that means anything.
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We are not sure if the brake reservoir had gotten completely empty. We thought if the reservoir did get empty - is it possible air got trapped
in the abs module. We tried researching a little online. Honda does not seem to have different instructions for bleeding with abs. I found post on just answer - where a honda tech was advising on replacing abs module on 2007 civic and I can not see anything where the honda tech advises bleeding the abs module.
I saw some posts where guys discuss air in abs module and then drive down gravel road to activate abs module - kinda burb out air from abs module and then bleed the system. Also saw few guys discuss using a scanner to activate abs and this then then forces air out and then bleed. My scanner cant do that abs activation ( no bidirectional support).
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I think I am likely going to take the car to my mechanic. He's great guy and great diagnostics skills - so, I'm sure he could figure it out. But, he's always super busy and often takes him some time to get to things. Anyone have any ideas or advice ?

Thx