Adding ASW-24 Brake Fluid

I am trying to fill the brake fluid reservoir of my ASW-24, but with no luck.

I am following the Schleicher Maintenance Manual procedure. It has you adding the fluid into the bleed valve of the caliper.

First you have to attach a funnel to a 6 ft length of instrument tubing. The tubing is attached to the nipple of the bleed valve. The funnel is held about 6 ft high. You then add the hydraulic fluid to the funnel and then open the bleed valve. The head pressure of the fluid in the funnel/tubing is suppose to drive the fluid up through the system into the hydraulic fluid reservoir.

The problem is that even after opening the bleed value no fluid moved into the reservoir. I even added vacuum pressure to the vent of the reservoir to try and draw the fluid into the reservoir, but that did not help.

Does anyone have suggestions?

Thanks,

Lauren Rezac
5YA

Try using a oiler pump can ( any hardware store should have ). Attach instrument to spout and pump the hydraulic fluid into the reservoir.

Thanks, will do

What is it about the ASW brake system that you need to add brake fluid at the bottom bleed valve? Seems like a very good way to add air into the system. Every other hydraulic brake system I know of you add fluid to the reservoir at the top and bleed any air out the bottom.

Thanks, John

On Saturday, October 29, 2016 at 2:09:20 AM UTC-4, OHM Ω wrote:
What is it about the ASW brake system that you need to add brake fluid at the bottom bleed valve? Seems like a very good way to add air into the system. Every other hydraulic brake system I know of you add fluid to the reservoir at the top and bleed any air out the bottom.

Thanks, John

Not in my world. Add to the bottom- bubbles go up.
UH

Possibly the bleed valve is clogged. If not already tested, try draining some fluid out first to see if the valve flows freely. I changed the fluid in my 24B using the manual method and it worked as described.

This syringe and tube on Amazon is well made, seals well (no leakage I could determine), can pump or suck (we won't go there), comes with spare seals, and is not expensive. Should work just fine with 5606 fluid (the petroleum based red brake fluid as used in Schleichers:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Two things when bleeding brakes, if the caliper brake line doesn't enter from the very top, then an air bubble can be trapped within. Best to take off the caliper and clamp the piston in with a C-clamp (so it doesn't pop out and make a mess!), then with the caliper brake line at the top, pressure bleed from the bottom.

Be sure to empty the reservoir while doing this. On some brake systems you will need to bleed with, um, gusto, to move air trapped in the lines at any high points out and up. I have a small pump up garden sprayer for this that work nicely (the the syringe above should do okay for small jobs - a plus is it will also drain the fluid from the reservoir).

5606 can turn to goo, partially solidify after many years of not bleeding or changing fluid. This can be recognized as very low or almost no fluid pumping in from the bleed valve. On one system I removed the bleed valve and installed a temporary nipple - then really got so flow going to clear things out. To that end, you can also install a nipple in the lid of your brake reservoir, this will allow surplus fluid to be drained off during the bleeding process without having to repeatedly stop to drain the reservoir. (Hint, do not try to fashion a temporary drain system using a male catheter - this will create much sorrow and mess to clean up as the material is completely incompatible with the rubber which will fail in short order. I think if there's a dumb trick - I've tried it.)

Oh, it's also a good idea to exercise the cockpit brake lever a couple of times whilst bleeding.

Fun.

Enjoy,

bumper