Brake bleeding issue?

Did you bleed the rear brakes first? They need to be in order, RR, LR, RF, LF.

Let me know if that is what you have done.

Take care,

Joe

Yes rear, left rear, passenger front, front driver. I've been bleeding my own brakes for approx. 40 years. This is the first time the rear brake bleeding is distinctly different front the front. Thanks

Thanks.

Are you getting any pressure from the rears when bleeding? Also, does the truck have ABS or not?

You may want to consider pressure bleeding the system, but I need to know if you have ABS or not to get the correct directions.

Let me know.

Joe

Yes, right rear, left rear, passenger front, front driver. I've been bleeding my own brakes for approximately 40 years. This is the first time the rear brake bleeding is distinctly different front the front.

Yesterday I had my wife help me pressure bleed. Air bubbles were removed and then only fluid as desired on the rear. However, the brake pedal still has a hard stop 2/3 down to the floor. I spoke to a local guy at Oreilly's. He suggested removing both rear hard lines and brake clean them. I did so. What was strange is the small junction box dripped fluid under gravity, but I was able to pressure pump the pedal up with several pumps. Might imply proportional valve broken? I also disconnected all my lines to my proportional valve and sprayed them out with brake clean. I reassembled and did pressure bleed rear to front and same symptoms, front goes to floor bleeding and rear hard stops at 2/3 travel. I was able to overcome the proportional valve at about 35 mph and lock up the brakes. However, the valve prevents a lock up very well as designed without extra hard attempt to brake super hard. I would suspect a blockage but for the exact 2/3 travel lock at the same point and only on the rear bleeding. I am beginning to think the prop valve may have a lock point for the rear when bleeding by design??? If so, I've never run into this but overall, the brakes seem closer to normal. It's just very confusing for the rear bleeding to have a pedal travel stop point. I am certain all air is removed on all 4 wheels under pressure. Now I plan to take short trips and gain basic confidence that all well in spite of this unusual bleeding behavior. Have you ever heard of the rear brake bleeding limiting pedal travel? And of course, being able to build pedal pressure with rear lines removed and minimal fluid coming out with engine off seems like something is still wrong? However, with engine running much more fluid will bleed into the tube I attached to the bottle to prevent air draw. It is almost like electric wire to prop valve must be activated for rear bleeding? Just strangest brake situation I've ever experienced or heard of.... No ABS.

Hi,

I've never experienced this. As far as the ABS, I was thinking if it had ABS, we may have needed to bleed it via a scan tool. However, even then, the pedal should reach the floor if the rear lines are open.

Something is restricting the brakes. It could very well be the proportioning valve that is faulty and preventing or restricting an opening for the rear.

Just for curiosity, when the pedal stopped with a rear bleeder open, would the pedal slowly go to the floor if you kept the pressure on it?


Joe

No, the pedal hard stops, and I can push as hard as I want to or wait a minute or more with full pressure and it does not budge. I did not try to push on it for a longer period of time, but I don't think it would move. Just an extremely hard stop and always at the same travel point of about 2/3 down to the floor. The electric line on the prop valve looks like a vacuum connector under the rubber connection. It may be "closed" by default and opens on engine start and brake push. I drove the truck 60-mile round trip today. It brakes but is still too close to the floor to be correct. I used it to hold on a 30-degree driveway at stop at one point. It holds but the pedal is too far down to be fully normal.

Hi,

I don't like the feeling of a low pedal either. Are the rear brakes fully adjusted? That can cause the low pedal but not the bleeding issue.

I came across a height-sensing proportioning valve and attached adjustment directions below. By any chance, do you have this set up?

Let me know.

Joe

See pics below.