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Discussion Topic:
Bleeding brakes
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Dustbowl |
02-18-2020 @ 8:55 AM
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Member
Posts: 74
Joined: Feb 2011
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Thanks for useful replies but I'm still hopeful to hear from someone who has info on flow rate with power bleeder.
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TomO |
02-18-2020 @ 6:57 AM
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Senior
Posts: 7244
Joined: Oct 2009
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Are you using DOT 5 fluid? A pressure bleeder is not recommended for DOT 5 fluid as it can introduce air into the fluid. If you are using DOT 3, 4 or one of the newer synthetic fluids, are you still getting air out of all of the wheel cylinders? if you are, the master cylinder is defective. You should be able to purge the air from the system using about 1 pint of fluid. If you are not getting air out of the system and still have a spongy pedal, the master cylinder or one of the wheel cylinders could be bad. Tom
This message was edited by TomO on 2-18-20 @ 9:00 AM
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37RAGTOPMAN |
02-18-2020 @ 6:10 AM
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Senior
Posts: 1942
Joined: Oct 2009
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HI try just applying a little pressure on the brake pedal and hold it there, and see if it goes down if it does the master cylinder is defective, [brake fluid is passing the piston,bad seals ] also make sure you have some free play in the brake pedal rod, so piston returns,fully 1 inch of free play is normal also test your power bleeder, to see if brake fluid is not restricted, dirt etc, I do it the old fashion method by foot, with a clear hose and bottle, and with a helper, hope this helps 1937 RAGTOPMAN
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kubes40 |
02-18-2020 @ 4:57 AM
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Senior
Posts: 3374
Joined: Oct 2009
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I too use a power bleeder on all of my projects. I start with 20#. The flow is smooth - difficult to describe in words. However, all of the air is forced through. I place a translucent line over the bleeder vale with the "open' end in a jar of fluid. That way, it is easy for me to see when the bubbles stop. If you still have a soft pedal after installing a new master, I'd suggest the master is defective. That is of course assuming your system was good prior to the (first) master becoming problematic.
Mike "Kube" Kubarth
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Dustbowl |
02-17-2020 @ 12:13 PM
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Member
Posts: 74
Joined: Feb 2011
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I had to replace my 39 Ford master cylinder because of crack and leak. I bench purged the new one before installing. Then I used a power bleeder to purge about a quart of new fluid thru each wheel. But the brake pedal is still soft after this. I have done this bleeding successfully before and went exactly by instructions this time keeping about 25-30 psi on the power bleeder. I noted this time that there was a seemingly low flow of fluid out of each bleeder (done one at a time). It took about ten minutes of flow to collect one quart of fluid in my receiving jar. I have three specific questions for you: 1. Is the flow rate I observed normal or low in your experience? 2 If low, what could cause this? 3. If low, could this slow rate fail to purge air out of high spots in the hydraulic system? thanks Phillip
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