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Discussion Starter · #1 ·
I've had an ongoing issue with my brake reservoir ever since the first brake job I did. Simply put, it will only fill about halfway (to the seam where the top and bottom halves meet) and after that fluid just sits in the neck. This is only about halfway full and I like to keep my fluids more topped off than this. I've done multiple pad replacements, bleeds, and a couple rear caliper replacements (which is what I did yesterday) and have had this issue in varying degrees. Brakes working fine, no soft pedal or anything weird. I just want to know why the dam fluid won't drain down in!

Anyone know what's going on and if so how to fix it?

('03 1.8T AWM 5M w/153K)
 

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The stupid screen creates surface tension or something. Either remove the screen or pulse it up and down a bunch with a blunt object.
 

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Discussion Starter · #3 ·
Screen doesn't looked clogged or anything. I'm always leery of putting anything other than brake fluid in contact with anything in the system for fear of contaminating it but I'll try to find something plastic that will work to do this and give it a shot.
 

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Look carefully at the side of the brake fluid reservoir, and you should see small molded-in icons. The ▲ shows the minimum level of brake fluid, mid-way in the lower segment of the reservoir. The ▼ shows the maximum level, and it's right at the horizontal joint between the two reservoir segments. Perhaps you're trying to overfill the reservoir.
 

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Discussion Starter · #5 ·
On my reservoir the upper and lower fill arrows point to locations about 1cm above and below seam joint. My fluid level (viewed from the drivers side and confirmed by rocking the vehicle and watching the fluid inside) is right at the seam so this would seem to be halfway. Again, its OK but I prefer to keep fluids topped off closer to the full side of things, especially something like brakes which will naturally drain the reserve fluid as the pads wear down over time.

Yesterday I pulled off the cap and the fluid was still sitting in the neck. I tried using a plastic implement to get the fluid to go down, no joy. Stayed at the same level. I didn't pull the screen since its a PIA. I opened the drain plug and there was also fluid sitting in this little area. I used my vacuum pump to suction them both out and put it all back together since I had to leave for the day.

Just now I went down and opened it all back up. No fluid in the either area so I again tried to top off the tank. To my surprise the fluid again filled the neck of the filler opening but somehow also found its way into the drain area but would NOT go into the main tank. The level viewed from the side and verified as above, remains in the same place.

This tank obviously has some kind of serious design flaw. I'm not the only one reporting this issue. There's no way it should be able to get permanently air locked or whatever the problem is preventing it from being filled to a proper level.
 
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