Home » Public Forums » GMCnet » [GMCnet] Brake Bleeding 101
| Re: [GMCnet] Brake Bleeding 101 [message #295500 is a reply to message #295479] |
Sat, 13 February 2016 16:17   |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma:
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Senior Member |
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G'day,
Jim .left out a several things I thought I would mention:
1) The plate that Jim makes that sits on top of the master cylinder is made out of THICK aluminum (does NOT leak) and has two short
(1/4") long tubes that fill the M/C to the proper level. The ones you buy at auto parts stores are made of plastic and LEAK!
2) I agree with him, Matt, and anyone else that says to wrap the bleeder screws with Teflon tape, HOWEVER, do not make it lots of
wraps one and a half to two MAX.! If you use more it will just get pushed out when you screw the bleeder in.
3) I checked the GENERAL INFORMATION, PERIODIC MAINTENANCE, and LUBRICATION section as well as the BRAKES section of all three MM's
and NONE of them advise that the brake fluid should be flushed regularly! Dot 3 and 4 are hydroscopic and absorb water which in turn
will cause the bore of the master cylinder, calipers, and wheel cylinders to rust. I use ATE Racing Brake fluid which recommends
flushing every three years.
I would suggest to those of you who bleed the brakes by getting your wife to help, vacuum bleed, gravity bleed, whatever should
consider buying one of Jim's pressure bleeders.
http://www.bdub.net/jhupy/
Note that he even sells the plate on it's own so you can use the garden sprayer you have already.
I've been asking him to take photos of the current model that uses cables instead of chains and send them to Bdub!
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: James Hupy
A bit of clarification on the use of a pressure bleeder.
1. This applies to a bleeder like the one I produce that pressurizes both
resevoirs with the same amount of pressure. When the top is securely
fastened, pressure throughout the system is equal to the gage reading on
the pump tank. Somewhere between 10 and 15 psi is sufficient.
2. Verify that the distribution valve plunger is depressed before any
attempt is made to open any bleeder. It is located in the drivers side
wheel well, and the plunger valve is towards the front of the coach. It
looks like a nail head sticking out of the end of the valve. The shop
manual shows a tool made specifically for holding the valve depressed.
Many, Many, of these valves are stuck due to rust and grunge in the brake
system. If yours is stuck, you might try TAPPING LIGHTLY on it to see if it
will free up. If it does not, replace the distribution valve, or
disassemble the valve in the false hope that it can be freed up. Then,
proceed with replacing the valve after you have made a big mess, wasted a
bunch of time, and failed.
3. Finally, if the valve does work, start with the wheel cylinder that is
the greatest distance from the master cylinder, loosen the bleeder screw
and let the fluid flow into the bleeder catch bottle until no bubbles are
seen in the stream. Close the bleeder screw and go to the next wheel
cylinder and repeat. Because there is internal pressure in the wheel
cylinder, even if you do get some leakage around the threads of the bleeder
screw, you will not suck any air back into the system. IF YOU ARE USING A
VACUUM BLEEDER INSTEAD OF A PRESSURE BLEEDER, SOME AIR CAN BE SUCKED INTO
THE SYSTEM AROUND THE BLEED SCREWS. THAT IS WHERE YOU MIGHT USE A BIT OF
SILICONE GREASE OR TEFLON TAPE ON THE BLEED SCREWS. Be very clean in your
work. Double check that you have no fluid leaks anywhere. A clean dry
finger works best here. Remember, your very life and the lives of others
depends upon YOU doing a good job here. If in doubt, call me and I will
talk you through the process. My phone number as well as my web address in
on the information sheet that came with my bleeder kit.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sat, Feb 13, 2016 at 4:38 AM, Matt Colie wrote:
> Please, if you live some that has any corrosion issues or might ever visit
> someplace that has corrosion as a remote possibility, either wrap the bleed
> screws with teflon tape or coat them with a teflon filled pipe thread
> sealant. If the rubber bleeder caps are missing or old, replace them.
> If you do this, you will find that the next time you need to bleed the
> brake system, you can actually loosen and use the bleeders.
> Sealing the bleeder threads also keeps the brake fluid from getting into
> the threads and helping them corrode. The pipe sealant will work too, but
> teflon tape works better (it just wasn't my idea).
>
> If you are not working with an old iron reservoir, vacuum bleeding works
> even better with the bleeder threads sealed.
>
> Matt
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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