88 Brake issue

ltracer91r · 10-31-2009, 11:59 AM

Ok guys,

I have a 88 chevy 1/2 ton 2wd
Power brakes
New master cyc.

My brake light flashes the entire time the truck is running;
And when I push the brakes they are soft, then get firmer,
But still slowly go almost all the way to the floor.
Any Idea on how to get these things firm again!?

Thanks in Advance!

leolkfrm · 10-31-2009, 12:18 PM

sounds like air in the system, bleed it till you have fresh fluid at all wheels, did you bleed the new master before install?

BernieB · 10-31-2009, 12:31 PM

Two problems... Air in the lines (did you bench bleed the master?) and possibly a defective master. Was the master new, or a rebuild? If a rebuild, chances are it's a bad rebuild.

gmctrucks · 10-31-2009, 12:31 PM

Did you bench bench bleed the master cylinder to start with? If so then start bleeding all the brakes starting from the one that's farther-es from your master cylinder remember don't let the reservoir run dry.

I started to reply to the thread and I thought I was going to be the first one then my sister called me.

ltracer91r · 10-31-2009, 12:51 PM

Yes, the master is bench bled, and there is no air in the lines.

BernieB · 10-31-2009, 02:03 PM

Quote:

Originally Posted by ltracer91r

Yes, the master is bench bled, and there is no air in the lines.

I beg to differ... The symptoms you're giving are the classic symptoms of air in the lines. Fluids are non-compressible, which is why they are used in applications like this. For a pedal to feel "soft" either something is compressing, or something elastic is expanding. There are no other possibilities. So, either you have air in the system or your brake hoses are swelling up like water balloons.

And the sinking pedal is the classic symptom of a bad master that's letting fluid past the piston seal.

Case 7230 · 10-31-2009, 02:20 PM

Does the truck have the RWAL brake system. If so may be a faulty valve module.

1500cheyenne96 · 10-31-2009, 03:30 PM

Possible bad power booster?

BernieB · 10-31-2009, 04:10 PM

Quote:

Originally Posted by 1500cheyenne96

Possible bad power booster?

A bad power booster would make the pedal harder, not softer.

ltracer91r · 10-31-2009, 04:26 PM

ok, so I just re-bled the brakes and I got the light to go out.

Now the tricky question:
When I do slow steady stops the pedal constantly needs to be pushed farther and farther down.
But when I do Harsh, fast stops it doesn't.
I tried putting in neutral and revving at higher RPM's when slowing to see if it would change it at all(power booster) but it did the same thing.

Any Ideas?

10-31-2009, 11:59 AM	#1
ltracer91r Full Member Join Date: Aug 2009 Location: Northern California Posts: 14	88 Brake issue Ok guys, I have a 88 chevy 1/2 ton 2wd Power brakes New master cyc. My brake light flashes the entire time the truck is running; And when I push the brakes they are soft, then get firmer, But still slowly go almost all the way to the floor. Any Idea on how to get these things firm again!? Thanks in Advance!

10-31-2009, 12:18 PM	#2
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,300	sounds like air in the system, bleed it till you have fresh fluid at all wheels, did you bleed the new master before install? __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

10-31-2009, 12:31 PM	#3
BernieB Senior Member Join Date: Jul 2009 Location: Fredericksburg, VA Posts: 1,906	Two problems... Air in the lines (did you bench bleed the master?) and possibly a defective master. Was the master new, or a rebuild? If a rebuild, chances are it's a bad rebuild. __________________ If the guys who design 'em had to take one home, use it every day for 2 years, and do all the maint and repairs themselves, cars would have a button on the dash to change the oil, filters & plugs.

10-31-2009, 12:31 PM	#4
gmctrucks Senior Member Join Date: Nov 2006 Location: Houston,Texas Posts: 4,035	Did you bench bench bleed the master cylinder to start with? If so then start bleeding all the brakes starting from the one that's farther-es from your master cylinder remember don't let the reservoir run dry. I started to reply to the thread and I thought I was going to be the first one then my sister called me. Last edited by gmctrucks; 10-31-2009 at 12:35 PM. Reason: add

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10-31-2009, 12:51 PM	#5
ltracer91r Full Member Join Date: Aug 2009 Location: Northern California Posts: 14	Yes, the master is bench bled, and there is no air in the lines.

10-31-2009, 02:20 PM	#7
Case 7230 Senior Member Join Date: Dec 2007 Posts: 547	Does the truck have the RWAL brake system. If so may be a faulty valve module.

10-31-2009, 03:30 PM	#8
1500cheyenne96 Senior Member Join Date: Sep 2009 Location: MIchigan Posts: 200	Possible bad power booster?

10-31-2009, 04:26 PM	#10
ltracer91r Full Member Join Date: Aug 2009 Location: Northern California Posts: 14	ok, so I just re-bled the brakes and I got the light to go out. Now the tricky question: When I do slow steady stops the pedal constantly needs to be pushed farther and farther down. But when I do Harsh, fast stops it doesn't. I tried putting in neutral and revving at higher RPM's when slowing to see if it would change it at all(power booster) but it did the same thing. Any Ideas?

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