do I have air bubble in my braking circuit?

[tocoo]

FOr the first time today I changed the braking fluid. I have a bottle of DOT4 and I opened the tank to fill up a bit with new fluid.
At the bottom with the nipple 8mmm valve, I attach a 8mm wrench and a hose. Then I pump 5 times the brake handle and keep pressing the handle and I open the 8mm valve until no fluid squirts and then I close the valve and let go of the handle. i do this until I am satisfied with the color at the output of the valve. Then I fill up the tank with new brake fluid up to the max level and I put back the rubber cap then the metallic cap.

I cleaned well the 8mm valve, but during the test drive to check the front brake by braking at various speeds, I notice that the little rubber cap was wet of DOT4, whereas I dried it just before. So I dried it several times and several times it became wet....
I closed the valve even more with a ratchet, but the rubber cap kept getting wet.

Now with the air bubble: I decided to open the 8mm valve with the ratchet and to close it normally, because I thought that I tightened it too much the second time. At this point the valve leaks some of DOT4 until I closed it properly. And I wonder if this fact means that there is air in the braking circuit now. I think there is still plenty of fluid left by judging with the handle, so I am not worried about lack fluid.

If there is air now, is it dangerous and how do I remove it? Wouldn't the air bubbles move back up to the top of the tank and just stay there, harming nothing ?



 

[GrumpyUnk]

The system is simple enough that gravity draining and refilling the reservoir should work adequately.

If you open the bleed screw on the brake caliper, and operate the lever, fluid should squirt out. If you then close the bleeder screw while holding the lever, you should successfully bleed the system of air. Bubbles can also come up into the reservoir through the tiny hole in the bottom of the reservoir.
You may have gotten a bit of debris under the bleeder screw which was then displaced by your opening and closing the valve.
tom

[tocoo]

On this video, www.youtube.com/watch?v=Jf1dBSMjr54, the guy says that leaving a pressure on the handle over 1 night is enough to get the bubbles at the top. In the comments, somebody says that under daily use, the bubbles will go up naturally.


Anyway, I will do again a bleeding, like we advise.
another thing: there was white deposits floating in the tank. I think there is a white coat at the bottom of the tank, near the output of the tank. I tried to remove it with a tiny screwdriver, but it not solid. it is very tenuous and I cannot grasp it.

I would like to flush the tank to clean it well, but I fear that I would remove too much fluid and make things work with respect to air bubbles.

[scooterpimp]

Been gravity bleeding for years , fill the res. Open bleeder & let it drip. (Into container with hose to keep brake fluid off scoot) keep res topped up , then snug bleeder & reinstall cap. If changing/ upgrading fluid be sure old fluid is completely purged.

[GrumpyUnk]

You can empty the tank and use a rag or paper towel to mop up the white stuff. There is a tiny hole in the bottom that can get plugged, especially if the brakes are not used for a while. It needs to be open to allow fluid to flow into the cylinder so the piston can push on it and send fluid to the caliper. Make sure it is open and unblocked by anything.
tom

[SMALL CC TEK]

Bleeding brakes can be a 10 minute job or a hour job ! Pumping the brake lever several times then holding the lever and then releasing the bleed valve is how it's done but you must watch for the small bubbles in the reservoir as you pump the lever .It takes a feel for what is or isn't happening at the time . Here is a tip that i learned in the early 90's when i racing 4 wheelers . On a system that won't bleed quickly and won't give you a nice feeling lever try this .

Bleed the system the best you possibly can ,most times that is where you have a decent lever but it is not where you like it and you have pumped till your hand is cramped . Pull the lever to the grip and zip tie it and leave it for a hour or more even over night make sure the system is full leave the cap off the reservoir , the air will rise and the bubbles will pop up in the reservoir in a pattern like 1,2, nothing 1,2 etc . I would do the brake line jobs be for we went home for the night and let it sit like that all night, then in the morning you just undo the zip tie and pump a few times slow and pow it pumps up hard or spongy depends on your preference ... That works about 80 % of the time if it doesn't you might think about just using a mighty vac on the system i do that only when i get one that just wont pump at all !!