The Portal Hub: All things Pinzgauer, Haflinger, Volvo 303 and more.

The Portal Hub: All things Pinzgauer, Haflinger, Volvo 303 and more.

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 Flushing brake fluid 
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Joined: Thu Jul 29, 2004 2:12 pm
Posts: 723
Location: Indio, California
Post Flushing brake fluid
I had read about pneumatic brake bleeders, and found one at Harbor Freight.

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First, connect the filler bottle full of brake fluid to the master cylinder. I used the adapter that came with my pressure bleeder to make this work.

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Next, connect the collector bottle to the bleeder valve and pull the air trigger. Then open the bleeder valve and watch it suck out old brake fluid while the bottle fills what is removed. The air pressure creates a vacuum somehow that draws the fluid out.

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Sounds easy, right? It is, all I had to do was keep an eye on the master cylinder reservoir and not let it go dry. The fluid moves pretty fast, so I couldn't leave the garage. But when it came to the test drive later on, the Pinz had no brakes, or at least minimal. As to what went wrong, I have no idea. Air didn't get into the master cylinder, and it certainly didn't get in at the bleeders. Or did it? I don't know. I ended up bleeding the brakes manually, the old fashioned way. The brakes work fine now, better than ever, but I'm still wondering what went wrong. Overall, it is an easy way to flush a system if you don't mind bleeding everything afterward.


Mon Nov 23, 2015 10:03 am
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Joined: Thu Oct 06, 2011 4:25 pm
Posts: 694
Location: Mount Vernon WA USA
Post Re: Flushing brake fluid
So this is a vacuum system - right? Most likely it pulled air in through one of the "lip" seals in one of the cylinders since they are designed to seal against pressure from inside the cylinder and not a vacuum...

If you have a pressure bleeder, why did you go this route? I have one (a pressure bleeder) and think it works very well.

For the tank that you connected to the master - wouldn't it collapse (have to get sucked inward) as the fluid was drawn out of it?


Mon Nov 23, 2015 11:07 am
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Joined: Thu Jul 29, 2004 2:12 pm
Posts: 723
Location: Indio, California
Post Re: Flushing brake fluid
Why didn't I use the pressure bleeder? Good question, since that is a proven successful method. I honestly thought this would work just as well, and found out otherwise. As for the fill bottle, I took the right cap off of the reservoir which then acted as a vent, allowing air in as fluid was displaced.
I think the pneumatic bleeder is headed for the landfill, but I will keep the fill bottle and bleeder line. Overall, it was a cheap lesson in how not to do brake maintenance.


Mon Nov 23, 2015 12:01 pm
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Joined: Fri Apr 16, 2004 7:08 am
Posts: 1696
Location: Blue Mounds, WI
Post Re: Flushing brake fluid
pinzinator wrote:
I think the pneumatic bleeder is headed for the landfill, but I will keep the fill bottle and bleeder line. Overall, it was a cheap lesson in how not to do brake maintenance.


Go ahead, Vince.. Say: "I told ya so!". :twisted: You deserve it.


Mon Nov 23, 2015 4:05 pm
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Joined: Sun Dec 22, 2013 5:53 pm
Posts: 101
Location: Melbourne Australia
Post Re: Flushing brake fluid
I have a very similar tool to yours, looks almost the same and the principal is identical. In the instructions it says the vacuum unit must be kept higher than the bleeding point ie. the nipple, I fashioned a hook to hang it from suspension or anything above the wheel area.

I've had it for years and used it on heaps of different vehicles...trucks, cars and inbetween but not on my Pinz yet, some vehicles the result is perfect others require a quick once around bleed afterwards to finish off, I always attributed this to variations in brake line design and the low end quality of my bleeder, a more professional unit would likely work better but they cost an arm and a leg. Overall I'm pretty happy with it as it has saved a lot of time over the years and it allows one to work alone. Don't throw it away it will come in handy one day. Mine has never left me with no brakes as you described, next time keep it above the bleeding point it might work better.

Mine worked particularly well on hydraulic cluthes of quite a few older trucks especially those with air over hydraulic systems found in heavy trucks but also in normal hydraulic clutches. It was great because the slave design of many of these cylinders is such that they won't gravity fill and no amount of pedal pumping gets them full either, likewise prefilling also didn't work because the piston pushes back to cover the filling bore. But with my cheap bleeder and a leverage bar to take pressure off the piston I could quickly get these slaves to fill and most importantly while on my own.... Asking that particular boss for a hand was not worth the trouble. For this reason alone my little vacuum bleeder earnt its cost price.

_________________
1985 pinzgauer 712K factory 2.7lt civilian (RHD, 4 door K)
1979 Volvo tgb 1314a (under construction to om606 diesel/722.6 trans. Dual cab/tray)


Tue Nov 24, 2015 7:34 pm
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