06 Ranger (break pedal to the floor)

[the_twig_187]

another tech in the shop did a break job on the service managers ranger a month ago. he gave it to me and said he is having break pulsations and to take a look at it. I found that the right side caliper had a large chunk taken out of the piston ( compressed with channel locks) and the left side also had a chunk taken out of the piston. I replaced the calipers as I normally would have, I pinched the line with needle nose vice grips that had pieces of vacuum line on the teeth not to damage the flex hose. When I reassembled it and went to bleed the brakes, the pedal went straight to the floor. I bled all four brakes and the bleeder screw on the master cylinder and still the break pedal goes straight to the floor. when I was bleeding there was no air that came out of any of the brakes during the bleeding. the master cylinder is filled to the full line and when the brakes are pumped the master cylinder reservoir fluid goes down and then when pumping stops the reservoir over flows with brake fluid. I have no clue what is going on here

 

things I have done to attempt to correct the break pedal to the floor issue:

1) bleed all four brakes and the master cylinder bleeder screw

2) adjust the parking brake shoes to the edge of the drums

3) check for leaks (no leaks found)

 

anyone got any ideas?

[8WA Sman]

I used to pinch off brakes hoses years ago but I have since stopped doing it, some/most brake hoses have some type of inner layer that does not like being pinched. Have you checked your brake hoses when you have the pedal pushed down,one guess I have is that you are filling the outer layer of the hose, then when you release the pedal if it returns to the master cylinder. Option two is when the brake pedal pumped up the master cylinder to fill the caliper pistons it can over extend the master cylinder outside of its normal travel and scratch the piston seals. Ask me how I know, I always try to fill the caliper pistons back up with short pedal pumps.

 

What normally do to see it the MC is the cause of the low pedal is block off the brake line ports with some plugs(brake line and fitting with the end soldered shut)

[mchan68]

ABS HCU dump solenoid(s) stuck open?

[Buddy_M]

Mix up calipers when replacing side for side? Calipers are installed so the bleeders are on top? I've seen it done, was at the end of a long week for a fellow coworker and just missed it when going together.

[Jim Warman]

I have seen it where collapsing the caliper without opening the bleeder screw can drive crap back into the HCU. I prefer to collect the old fluid and top off the master cylinder with fresh from a sealed container.( thereby "almost" performing a fluid swap ). As Buddy mentions, inadvertently mispositioning the calipers will  also cause such grief and something like that is only  one brain fart away.

 

Another consideration would be accidentally stroking the brake pedal all the way to the end and having the piston jam in the bottom of the bore.

[Steve Mutter]

Like Buddy pointed out make sure the bleeders are top.

[the_twig_187]

Yah that was it... At 5:30 pm I put the calipers upside down so an air pocket was at the top... Guy pointed it out to me in the morning and we all had a good laugh