| Academic question for the day [message #261232] |
Sun, 07 September 2014 19:46  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
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At what vacuum (pressure) level will 70 degree F. water boil?
Here is the issue.
I installed new pads, rotors, and hoses on the rear of a 16 year old Blazer. the brakes have never been bled before and now I'm trying to do that by vacuum bleeding. There is a lot air in the system because it was opened up for days while I waited for new hoses to arrive from Rock Auto. So I put it all together and started to suck out all of the old fluid and air out of it. I get to about 20" of vacuum and I see clean fluid with tiny, tiny bubbles. If I go to 25" of vacuum I see very large bubbles. I have the bleeders teflon taped and they do not leak air when closed. When opened 1/4 turn I now pull fluid and air bubbles.
So Now I'm thinking that brake fluid is hygroscopic and that fluid in there probably has all kinds of moisture in it. I'm looking for the source of the bubbles and I'm thinking that maybe at 25" of vacuum I'm actually boiling off some of the moisture absorbed by the fluid.
BTW,
This thing will not gravity bleed due to the ABS and I do not have an adapter to pressure bleed it. (I may have to make one.) The correct method is to use a $2000 scanner and force the fluid through.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
[Updated on: Sun, 07 September 2014 20:13] Report message to a moderator |
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