[123pugsy]

I have a friend with a 98 Blazer.
He found his brake fluid low after his brake light came on.
He's bleeding the front brakes and the air bubbles keep coming non stop.
There is no apparent leak anywhere that can be seen.

Any thoughts anyone?

[eloc431962]

why just bleeding the front?Iwould go and bleed them all just remember to start bleeding on the furthest wheel and work your way to the closest to the mc. the fluid could be by passing through his booster also. cole

[123pugsy]

Only the front was low.

I encountered the same thing on a Mercury Tracer.
I did the rears first and then the fronts wouldn't bleed without air bubbles.

He left my place, got down the road about a mile and called to report his brakes were working.

[eloc431962]

are you using a pump or gravity bleeding ? if you are using the pump do the gravity bleed it always works for me. cole

[123pugsy]

He was using the vacuum pump.
He's gone to take it to a mechanic.
I'm thinking its the master cylinder allowing air in somehow?
We'll see what the mechanic does and post back.
Thanks.

[KULTULZ]

Originally Posted by eloc431962

just remember to start bleeding on the furthest wheel and work your way to the closest to the mc.

What if he has a DIAGONAL HYDRAULIC BRAKING SYSTEM?

[123pugsy]

Originally Posted by KULTULZ

What if he has a DIAGONAL HYDRAULIC BRAKING SYSTEM?

Interesting.
Can you fill me in .
What is a diagonal braking system?

[eloc431962]

Originally Posted by KULTULZ

What if he has a DIAGONAL HYDRAULIC BRAKING SYSTEM?

humm i need to know more. cole

[KULTULZ]

It used to be that split hydraulic brakes (dual reservoir) were split between front and rear brakes. Newer tech has gone to diagonal whereas the left front and right rear are energized (and vicey-versy) from one of the split reservoirs to provide more stable braking in case of a partial hydraulic failure. This is more common twith he FWD and possibly anti-loc but it is a good idea to determine how the car was built.

Trying to bleed a new system as an old system will lead to much frustarion and beer abuse...

[Big Don]

This problem seems to be common lately. Usually on late model GM'S. Possible solution if the system seems to be in good working order and you cannot seem to get a good solid pedal.

1) Put a small torpedo level on the MC and see if it is level front to rear.
2) If it is not level, jack up the car, front or rear, to get the MC level.
3) Then do a manual bleed again.

If the system is sound this should clear up the problem. To detect if this is the problem or not simply remove the MC res. cap and have someone stroke the pedal (SLOWLY) and inspect the fluid as it moves in the res. If you detect ANY small bubbles, even one bubble, then this is the problem.

Dual diagonal brake systems are really not used on GM's anylonger (per. se.) they have shifted over to the proportioning valve styled system. However as described this doesn't sound like a proportioning valve problem.

[eloc431962]

makes sense to me now.have to check when bleeding brakes.instead of the old way RR/ LR /RF/ LF.the newer diagonal way will be RR/LF/LR/RF.It all makes sense if you are having trouble bleeding the brakes you need to know which system you have.thanks Kultulz we are never to old to learn. cole

[burnt olds]

VAC BLEEDING are the bleeder screws rapped with Teflon tape ?
will suck air by threads when you loosen them .
same if you use the hose in bottle of brake fluid and pump brakes method.

[powerrodsmike]

Originally Posted by burnt olds

VAC BLEEDING are the bleeder screws rapped with Teflon tape ?
will suck air by threads when you loosen them .
same if you use the hose in bottle of brake fluid and pump brakes method.

Burnt olds has it right...If the screws are loose, it will let air in the bled out fluid, when either vacuum or pressure bleeding...I see it all the time, and have found that a wrap of teflon tape or a dab of TFE paste on the threads only, and you will not have to try to figure out if the bubbles are from the mc.

If you look at a set of speedbleeders, they come with sealant on the threads already, so they don't suck air back in on the upstroke.

Later, mikey

[Bryan59EC]

Originally Posted by eloc431962

makes sense to me now.have to check when bleeding brakes.instead of the old way RR/ LR /RF/ LF.the newer diagonal way will be RR/LF/LR/RF.It all makes sense if you are having trouble bleeding the brakes you need to know which system you have.thanks Kultulz we are never to old to learn. cole

on x-frame chevies (probably all x-frame GM) the farthest wheel is the LEFT REAR

[eloc431962]

bryan59EC is this do to the route of the lines?just trying to figure out how the left rear would be the furthest from the mc. cole