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J. Clarke[_2_]

In article ,
says...

On Mon, 12 Dec 2011 08:45:51 -0800, "Bruce L. Bergman (munged human
readable)" wrote:

On Mon, 12 Dec 2011 05:36:17 -0800 (PST), stryped
wrote:

I replaced a section of rusted brake line under my truck when I had
the gas tank out. Two things I noticed, One, I had to make a very
sharp bend in the tubing with a tubing bender. It may be slightly
kinked. I was able to blow through it without any difficulty though.
Two, I used a compression fitting where the replacement line met the
old line.

You never ever Ever EVER use a compression fitting on brakes - they
can't take the1000+ PSI pressure and they WILL blow off after a few
panic level stops. It is literally a ticking time bomb.

You either get a proper double-vee (SAE) or double-bubble (for some
imports) flaring tool and a new length of tubing that goes fitting to
fitting and you flare the free end to length, or you order a pre-made
one from the dealer and change the entire length of tubing

I attempted to bleed the back brakes last night with a hand operated
vacuum pump. I opened the right rear wheel screw. Nothing came out
unless you press on the brake pedal. I could completely remove the
bleeder screw and nothing would come out. The driver side rear wheel
(one closest to the repair) came out fine but could not get rid of the
hundreds of bubbles.

The line to the rear drum brakes has a Residual Pressure check valve
at the master cylinder, so the rear cylinders don't fully retract -
otherwise they would be slow to act and require a much longer pedal
stroke.

You need to two-person bleed them, and do NOT stroke the pedal all the
way to the firewall. You'll rip up the master cylinder cup seals by
forcing them into the rough part at the end of the bore that never
gets swept, and it will start leaking on you. Or you need a
professional style pressure-pot bleeder, or a vacuum bleeder.

I am second guessing everythign now. My brake light on the dash came
on.

Is a compression fitting ok to use? It came from the auto parts store
and I checked it three times and it is not leaking.
Is it ok to replace the metal line with a flexxible line? That way I
would not have to make any bends.

You change the entire length of tubing, it's the only safe way. Oh,
and with the proper steel brake line and NOT with Copper Tubing,
that'll blow just as fast - any vibration at all and it'll work-harden
and fracture.

I am thinking I need to try to bleed everything manually. (With a
helper depressing the pedal). I am so frustrated.

It's a lot easier if you get a Factory Repair Manual for your car, and
follow the practices and procedures. Note that Haynes and Chilton (et
al) are NOT the Factory Manual, and some are less complete and
accurate than others...

Here, let me point you at the Factory Service Manuals:
http://www.helminc.com/helm/product2.asp?Make=CHV&Model=CHCK&Year=1996&Categor y=1&class_2=CHV&mk=Chevrolet+%26+Geo&yr=1996&md=C% 2FK+Pickup%2FSuburban%2FBlazer&dt=Shop%2FService+I nformation&module=&from=result&Style=helm&Sku=GMT9 6CKK&itemtype=K

They are $135 plus shipping, but this is 2 thick volumes that are
guaranteed to really cover your truck. My 1998 C/K set is 4 volumes
and a good 9" high stack of phone books. The UPS man got a hernia...

Note that the factory manuals figure you're a pro mechanic at a
dealership already, so they don't cover the 'grade school' stuff like
"Lefty Loosie, Righty Tightie" that you're already supposed to know -
but that won't trip you up if you're thinking about what you're doing.
You just need to know it.

The books and online services meant for Professional Mechanics
(All-Data, etc.) also assume you're already an expert mechanic in
general, so they don't go into the theories hardly at all - but they
tend to be better on the numbers and procedures, but you pay for it.
And the Pros don't pay if the book steers them wrong, so the
publishers tend to correct errors and omissions real fast.

You might be able to do something the "Easy Way" but it's likely to
come back and bite you in the ass later.

-- Bruce --

Everything Bruce said PLUS
If you need to ask these questions you have NO BUSINESS working on
safety critical systems like brakes - on a BICYCLE, much less a truck.

It is possible to "one man bleed" those brakes 99% without any special
tools - but it is an aquired skill. With a length of small hose to fit
the bleeder screw and a bottle it is a whole lot easier and you get it
100%.

A set of Speed Bleeders http://www.speedbleeder.com/size.htm makes the
job a whole lot easier.

Replacing the whole line is the only sensible way for an amateur to
repair a brake line because flaring the line (in place) also requires
some skill - you don't get it right the first time - and you do need
to know quite accurately how much line you need to buy the right
combination of ready flared lines and fittings to avoid having to
make too many complex bends and thread them through all the tight
spots in the average vehicle framework.

I have replaced partial lines on many vehicles over the years, using
proper flared lines and fittings - and flaring the lines on the
vehicle - but I'm a licenced mechanic who did it for quite a number of
years as part of my job - and I was properly trained and supervised
the first number of times to be sure I was doing it right.

Most DEFINITELY no copper lines, and no mickey-mousing around with
extra flex hoses, and NO compression fittings.