Re: Poor-man's pressure bleeder

[Igor Kessel <e6941tb@ix.netcom.com>]

Tony Lum wrote:
> 
> Coupla questions (Mr Goggin?) about schraeder valve on cap pressure bleeder.
> 
> 1. How did you get rid of the electrical level sensor in the middle (to
> attach the valve)?
> 
> 2. Since psi is so low, can't you pressurize the thing with a bicycle pump?
> 
> 3. How many calipers can you bleed before you must refill the resevoir?
> 
> Tony (who also wants to bleed his brakes the easy way :)

Here's a description of one poor-engineer's pressure bleeder:

1.The cap. Took the one from a 5000/100/200 P/S reservoir. It's the same cap as 
on the brake reservoir. I paid $5 at a junk yard. I took the float out and 
enlarged the hole to 0.476".
Got a regular rubber tire stem (the narrow one, there are 2 different O.D.). Ran 
it trough the 0.476" hole. I also machined an Al ring and knurled it on the 
outside. I've put this ring over the cap w/epoxy, so it prevents the plastic cap 
from expanding under pressure and popping off the reservoir.

2. The reservoir. Ordered a 1L chemical jar with a 110mm phenolic posin screw 
lid from Edmund Scientific. Drilled two 0.476" holes thru the lid, spaced 2" 
apart. Ran a tire stem thru one hole. Ran a chemical feed-thru union thru the 
other. Inserted a 0.25" hard plastic tube into union so that when the lid is 
screwed onto the jar the bottom tip of the tube touches the bottom of the jar in 
order to pick up brake fluid from the very bottom of the jar. To the other end 
of the union I connected a 1.5m Tygon hose with a quick disconnect for a tire 
stem on it's opposite end.
 
3. Pressure source. Took an old freon tank. Brazed a brass *T* to its valve. On 
that T installed a nipple for charging it from a regular shop air line, a 
pressure regulator with a dial gauge and a 1.5m Tygon hose with a quick 
disconnect for a tire stem.

Here's how I bleed the brakes:

1. Fill the car's brake fluid reservoir.
2. Screw the cap with tire stem on it.
3. Attach the quick disconnect from the jar lid to the tire stem.
4. Fill the jar with 1L of brake fluid. Screw the lid onto the jar.
5. Fill the modified freon tank with air to around 80psi.
6. Connect the quick disconnect from the freon tank to the tire stem on the 
jar's lid.
7. Adjust the air pressure to no more than 10psi! You can blow the seals with a 
higher pressure.
8. Bleed the clutch.
9. Bleed the wheels (RR, LR, RF, LF, RR).

Tips:

1. Test drive the bleeding sys with water first. A geiser of brake fluid WILL 
ruin your paint!
2. Keep a bucket of water handy for that inevidable spill-off. Should it ever 
happen to you (the cap pops off, the jar breaks - whatever, FLOOD the sucker 
with water!!! To repaint the car is a lot more expensive, than to rebleed the 
spoiled brake fluid.
3. Keep the jar in a container, when bleeding the brakes. I use an empty 1 gal 
tin (in which grocery stores sell olive oil).
4. Thoroughly cover the fenders with rags. If you spill brake fluid, you'll be 
glad you did cover them, coz you have about 20 sec to salvage your paint after 
which it's history.
5. Keep an eye on brake fluid level in the jar. If you miss and fill the MC and 
ABS unit with air, it will require rebleeding of the whole sys over again. No 
biggie, but it's time and brake fluid consuming.
6. Bleed the old fluid into a clear bottle of the same capacity as the jar - it 
will help you to determine how much fluid is left in the jar without having to 
crawl from under the car.
7. Bleed the old fluid out thru a clear Tygon hose (1/4" or 3/16 I.D. depending 
on the size of the bleeder screws). It will make bubbles visible.
8. Use only quality brake fluid. I like German Pentosin DOT-4. Some people on 
the list swear by ATE Racing Blue. Just don't use any Pep Toys, Quaker Trait and 
other no-name sh*t, it likes to ruin seals. The only acceptable domestic fluid 
would be Castrol LMA DOT-4.
 
-- 
Igor Kessel
'89 200TQ - 18psi (TAP)
'98 A4TQ - on order
Philadelphia, PA
USA