Brake problems

[joeplazek]

Check any where your rubber brakes hoses go through steel holders as these rust inside and squeeze the line off causing a restriction. Had this happen to mine and the brakes would stay on just enough to overheat and impossible to bleed. All I had to do was open up the holders just enough that the hose slide back and forth freely. Problem was solved.

joe

[whitetop]

Not sure this apply's or not.But by chance is the rod thru the fire wall that operates the master cylinder the same length? What I am saying is they can be adjusted for travel length.Good luck.

[Bcollier9253]

Originally Posted by whitetop

Not sure this apply's or not.But by chance is the rod thru the fire wall that operates the master cylinder the same length? What I am saying is they can be adjusted for travel length.Good luck.

I used the pushrod out of the old hydraboost in the new one

[whitetop]

You may want to make sure the length is correct,sure hope you figure it out I know how frustrating things like this can be. Happy Trails...

[Dave78Chief]

This may help you isolate where the issue is:

Obtain some Edelmann Inverted Flare Plugs in the size that fits your front and rear master cylinder brake line tubes (http://www.summitracing.com/search/p...-plug-fittings).

Remove both brake lines and install the Inverted Flare Plugs in the mastercylinder.

Start the engine and see if you have firm brakes. If not, then the problem is in the master cylinder or hydroboost unit. See page 4 of http://www.bepco.biz/Catalogs/VacHyd...LESHOOTING.pdf
If ok, remove plugs and reconnect the brake lines.

At the combination valve disconnect the line that goes to the rear brakes and install a Inverted Flare Plug in the combination valve. Bleed the front brakes and see if you still have the brake problem. If not, problem is in rear brakes. If still there it is the front brakes.

You should be able to isolate the problem from there.

Fix problem, bleed both front and rear again, reset brake light switch (part of bleeding process) and test drive.

Dave

[Bcollier9253]

Originally Posted by Dave78Chief

This may help you isolate where the issue is:

Obtain some Edelmann Inverted Flare Plugs in the size that fits your front and rear master cylinder brake line tubes (http://www.summitracing.com/search/p...-plug-fittings).

Remove both brake lines and install the Inverted Flare Plugs in the mastercylinder.

Start the engine and see if you have firm brakes. If not, then the problem is in the master cylinder or hydroboost unit. See page 4 of http://www.bepco.biz/Catalogs/VacHyd...LESHOOTING.pdf
If ok, remove plugs and reconnect the brake lines.

At the combination valve disconnect the line that goes to the rear brakes and install a Inverted Flare Plug in the combination valve. Bleed the front brakes and see if you still have the brake problem. If not, problem is in rear brakes. If still there it is the front brakes.

You should be able to isolate the problem from there.

Fix problem, bleed both front and rear again, reset brake light switch (part of bleeding process) and test drive.

Dave

This sounds like a plan that I will try. Thanks!

[whem2fish]

Dave is the man

[Bcollier9253]

Originally Posted by Dave78Chief

This may help you isolate where the issue is:

Obtain some Edelmann Inverted Flare Plugs in the size that fits your front and rear master cylinder brake line tubes (http://www.summitracing.com/search/p...-plug-fittings).

Remove both brake lines and install the Inverted Flare Plugs in the mastercylinder.

Start the engine and see if you have firm brakes. If not, then the problem is in the master cylinder or hydroboost unit. See page 4 of http://www.bepco.biz/Catalogs/VacHyd...LESHOOTING.pdf
If ok, remove plugs and reconnect the brake lines.

At the combination valve disconnect the line that goes to the rear brakes and install a Inverted Flare Plug in the combination valve. Bleed the front brakes and see if you still have the brake problem. If not, problem is in rear brakes. If still there it is the front brakes.

You should be able to isolate the problem from there.

Fix problem, bleed both front and rear again, reset brake light switch (part of bleeding process) and test drive.

Dave

How does one go about resetting the light switch?

[Dave78Chief]

The combination valve detects a loss of pressure in either the front or rear brake system. There is a slide valve inside of it that when pressure in one circuit is lost (i.e rear) the pressure in the other circuit (i.e front) pushes the valve off center resulting in the Brake Warning lamp being lit. So once the failed circuit has been repaired, the object is to use the pressure of the now functional circuit to push the slide valve back to it's center "home" position. You do this by simulating a lose of pressure in the system that did not fail.

Note: I am writing this with the assumption that you did a complete brake job and you do not know which system (front or rear) is causing the brake warning light to come on.

Bleed all air out of both front/rear systems (note: this in itself may reset the warning light)

Have helper pump up the brakes and hold. At the right rear wheel cylinder (or caliper) slowly crack the bleeder screw open until the brake warning light goes out. If, that does not turn the light off, repeat that procedure at the right front wheel. Object is to use the pressure in one circuit to push the slide valve back to it's center "home" position. Once set, the balanced pressure between the front and rear systems will keep the slide valve centered.

One additional note: The combination valve, sometimes referred to as a proportion valve, reduces the pressure to the rear brakes. When you apply the brakes, the weight of the vehicle is pushed forward via inertia. This will result in the rear wheels locking up before the fronts do. So, the proportion valve feature reduces the pressure to the rear brakes so they do not lock up before the front brakes.

While this does not apply to 4 wheel disk system, for vehicles that have front disk and rear drum brakes, the proportion valve also maintains a small amount of constant pressure on the rear circuit in order to keep the wheel cylinder piston/rubber cup pushed against the return springs to prevent leakage past the rubber wheel cylinder cup.

Dave

[terry735001]

i am not sure but i know on cars and SUVs arond that year if it has anti lock brakes system you have to send a open code to the ABS to bled all of systems Or it has the push butten on the ABS its self

i am not sure if your 91 Southwind P-30 chassis has ASB or just a load valve on the back axel

[Bcollier9253]

Originally Posted by Dave78Chief

The combination valve detects a loss of pressure in either the front or rear brake system. There is a slide valve inside of it that when pressure in one circuit is lost (i.e rear) the pressure in the other circuit (i.e front) pushes the valve off center resulting in the Brake Warning lamp being lit. So once the failed circuit has been repaired, the object is to use the pressure of the now functional circuit to push the slide valve back to it's center "home" position. You do this by simulating a lose of pressure in the system that did not fail.

Note: I am writing this with the assumption that you did a complete brake job and you do not know which system (front or rear) is causing the brake warning light to come on.

Bleed all air out of both front/rear systems (note: this in itself may reset the warning light)

Have helper pump up the brakes and hold. At the right rear wheel cylinder (or caliper) slowly crack the bleeder screw open until the brake warning light goes out. If, that does not turn the light off, repeat that procedure at the right front wheel. Object is to use the pressure in one circuit to push the slide valve back to it's center "home" position. Once set, the balanced pressure between the front and rear systems will keep the slide valve centered.

One additional note: The combination valve, sometimes referred to as a proportion valve, reduces the pressure to the rear brakes. When you apply the brakes, the weight of the vehicle is pushed forward via inertia. This will result in the rear wheels locking up before the fronts do. So, the proportion valve feature reduces the pressure to the rear brakes so they do not lock up before the front brakes.

While this does not apply to 4 wheel disk system, for vehicles that have front disk and rear drum brakes, the proportion valve also maintains a small amount of constant pressure on the rear circuit in order to keep the wheel cylinder piston/rubber cup pushed against the return springs to prevent leakage past the rubber wheel cylinder cup.

Dave

Thank ya kind sir. Your a wealth of information!!

[Bcollier9253]

Okay... I think the new master is bad so I put the ill one back on. While the combination- proportioning valve was off and the master plugged I had hard peddle, hooked everything back up and guess what.... soft peddle again. Tried to gravity bleed, probably ran about a quart of fluid, mostly thru the back brakes, they had a decent trickle coming out. The front on the other hand dont even have as much as a drop coming out., left them open for at least an hour. I can vacume the front and get fluid so why won't they gravity bleed?

[Dave78Chief]

I have never tried a gravity bleed. I have tried a vacuum bleed however the extra air bubbles (sucking air from bleeder screw threads) never made me feel comfortable that it worked. I always use a one man bleeder set up that forces all air out under pressure.

Autocraft 7 pc One-Man Brake Bleeder-AC558/W80625 - Advance Auto Parts





Dave

[Bcollier9253]

Just went out and checked the fluid level in the mc after the front bleeders being open all night, it was still full. ????