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airguy

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I need to fill my brake system with fluid, and I'm stuck without a helper for a while. I've got the cheap Harbor Freight vacuum handpump and I've got lines for drawing fluid in at the bleeders at each brake, but what about pumping the brakes in the cockpit? Is that necessary for the first fill or just later to work out the bubbles? Is this necessarily a 2-man job?
 
If you are filling from the bottom-up, pumping the pedals is not necessary.
Check valves will allow the fluid to flow upwards.
 
I have bled the brakes in my -7 twice now, solo. I connect the nozzle of the harbor freight oil can to a plastic hose that fits over the bleeder valve on the caliper and then start pumping. I also temporarily installed a push-to-connect fitting in the top of the reservoir with some extra pitot/static hose with the other end in a gallon size zipper bag. I then pumped and pumped and pumped some more. When I saw fluid going into the zip-lock bag (full reservoir), I shut the bleeder valve and connected the oil can to the other side. I pumped and pumped until I got more fluid going into the bag and then shut the bleeder. No need to pump the brake pedals. I then removed the hose and fitting at the top of the reservoir and drew some of the extra fluid out with an extra syringe I had in the shop.
 
I've done mine solo a couple of times; it's super easy.

I use a hand-cranked fuel pump for R/C models, a bunch of silicone tubing, and Mobil ATF as the brake fluid. Outlet from the pump goes to the nipple on the bottom of the brake, the inlet goes to the ATF bottle. There's enough tubing so I can see the plastic brake lines inside the cockpit while standing outside and turning the pump. Not terribly concerned if bubbles appear at this point.

Once the system is full (including the reservoir), I move the inlet from the ATF bottle to the reservoir and keep pumping. This circulates the fluid through the system and removes any air bubbles that might be in place.
 
There are many homemade ways to bleed the brakes from the bottom up.

You can also buy a pressure pot made for the task.

06-11413-1s.jpg


VAF advertiser Aircraft Spruce sells this one and it works great.
 
RV6_flyer said:
There are many homemade ways to bleed the brakes from the bottom up.

You can also buy a pressure pot made for the task.

VAF advertiser Aircraft Spruce sells this one and it works great.
Click to expand...

Wow, a $90 solution to a $2 problem :).
 
Ditch the Harbor Freight pump. I tried it and it wouldn't push the fluid high enough. I got a small garden sprayer like the expensive one pictured above at a True Value hardware store for $14. You just need some hose barbs and adapters and a couple of different sizes of clear tubing to make a nice solid connection. Put a drain hose on the reservoir and into a container to catch the over spill. Pump it up, connect the hose to the brake caliper, then crack the bleeder and it will fill up each line with no bubbles. Easy job to do solo. It turned out to be a really quick and easy task.
 
On some brake master cylinders (like the Matco units on my RV-12), you should make sure that the master cylinder is fully retracted before starting the bleeding process.
 
Speed Bleeders

Or, just replace your bleed fittings on your brakes with a pair of Russell Speed Bleeders. Connect a piece of tubing to the fitting, unscrew it 1/4 turn, fill the reservoir, pump the pedal until a bubble-free stream comes out the end and you're done.
 
krwalsh said:
Or, just replace your bleed fittings on your brakes with a pair of Russell Speed Bleeders. Connect a piece of tubing to the fitting, unscrew it 1/4 turn, fill the reservoir, pump the pedal until a bubble-free stream comes out the end and you're done.
Click to expand...

Kool idea...so what size is used??? Several choices on their website...


Rob S.
 
I am with Scott. I used a large syringe and a shot piece of tubing.
Fill syringe with fluid and pressure fill from the bottom. Watch all the air exit the top. Just don't let the reservoir overfill and make a mess.
 
Garden sprayer and tubing it is then, I happen to have a couple of these clean and handy.
 
Depends

Aggie78 said:
Kool idea...so what size is used??? Several choices on their website...
Click to expand...

That depends on your brakes. On our plane we have Matco brakes and they use a 1/4-28 bleed fitting. But even Matco has changed their bleeders over the years, and I cannot say. Measure yours and order the appropriate size. Amazon carries them from Russell and they're cheap and an easy solution to this problem.
 
So, you just use the weed sprayer to pump fluid in from the bottom... nice. How much fluid does the entire brake system on an RV take, with dual brakes?
 
krwalsh said:
Or, just replace your bleed fittings on your brakes with a pair of Russell Speed Bleeders. Connect a piece of tubing to the fitting, unscrew it 1/4 turn, fill the reservoir, pump the pedal until a bubble-free stream comes out the end and you're done.
Click to expand...

If you do this, the bleeder must be installed on the top with the brake line to the bottom to make it possible for the air to move up and out.
 
DaleB said:
So, you just use the weed sprayer to pump fluid in from the bottom... nice. How much fluid does the entire brake system on an RV take, with dual brakes?
Click to expand...

Yep, pretty simple! Do make sure your pedals are fully retracted before you start pumping.
It doesn't take much fluid to do the entire system.... I have maybe 3/5 of the Mobile 1 ATF quart remaining and that was after spilling a bunch during the process :rolleyes:
 
No HF el cheapo oil can

All good ideas and I too would not try again with the HF oil pumper.
I went through 2 of those el cheapo pumps and couldn't get any pressure out of them. Made a mess before I got smarter.
Spent a little extra for a pressure set up.
Piece of cake after that, no mess and no help needed.
Time to bleed a set of brakes, less than 10 minutes.
 
Just FYI - you get what you pay for in pumpers - buy a good one at NAPA and it will work great - I have a couple in different hangars and they haven't let me down. ACS sells a great little fitting for the end of the bleeder vlave that makes life so much easier than popping on a hose too - but you'll have to spend $26 for the luxury. With three (soon to be five) airplanes to maintain, it's worth it for me!
 
I've done car brake fluid replacement but not on am aircraft yet. Auto brake fluid is hydroscopic and I assume aircraft grade is too so make sure you use new fluid and get rid of the old stuff. I'm trying figure out what to do with old right now since my local Oriellys only takes oil.
 
rapid_ascent said:
I've done car brake fluid replacement but not on am aircraft yet. Auto brake fluid is hydroscopic and I assume aircraft grade is too so make sure you use new fluid and get rid of the old stuff. I'm trying figure out what to do with old right now since my local Oriellys only takes oil.
Click to expand...

Many auto brake fluids are glycol based and flammable. A few might be silicones, but most factories would not let than in and contaminate parts for painting.

I was told (can not recall where/who) that we should use Royce 756 - mineral based and fire resistant. It seems to be low on temperature capability, but recommended.

http://www.aircraftspruce.com/catalog/lgpages/anderolr756hf.php
 
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