MC failure after pad install

[Prairie Dog]

My buddy is a long time heavy equipment mechanic who has done many brake jobs on truck like ours.
Yesterday he put new pads on an 07 3500 and all seemed to go well. He re-used the calipers...
Today the driver takes off in the truck and after a couple of blocks, the brake pedal goes to the floor and they have very little brakes. They re-bled them with no change. The pedal just sinks under their foot so my buddy has ordered a new MC.
Is ther something special you have to do before you push the pistons back into the caliper?

What happened?

Scott

 

[seafish]

Is ther something special you have to do before you push the pistons back into the caliper?

What happened?

Scott

I like to open the bleed screw at the caliper before I push the pistons back in and then close it...this lets all the worst contaminated brake fluid out instead of pushing it back up the brake lines towards the MC.

NO idea if that is your problem, but it is SOP for me on all vehicles.

 

[sag2]

There should not be anything special about pushing the pistons back to make room for the new pads. Some vehicles use the scan tool to bleed the brakes if it has ABS, but I don't recall an 07 Ram being one of them.

 

[Prairie Dog]

Thanks Stan.
I'll have to ask him if he opened the bleeder.
I never had to do anything special on mine but I don't know if it's the same.

Scott

 

[Got HO?]

Have seen on occasion master cylinders with high miles fail after replacing brakes. If the pedal is pushed to the floor when seating the pads, the piston seals in the cylinder can be "lipped" or cut if a ridge has developed in the master cylinder bore from wear.

 

[cerberusiam]

Top reason why most places will not do anything except loaded calipers on a brake job. Disturbed the seal and run area when the new pads were put on, ANY build up in the brake cylinder cuts the seal. With the phenolic pistons in them and as hot as they get, calipers almost always need rebuilt or swapped when pads are changed. More planned obsolescence.

Hopefully he bled the calipers out and not pushed the fluid back into the system, that practice was discontinued on the LD vehicles +15 years ago. Pushing dirty fluid back into the ABS or MC is just not a good idea, and, the back pressure will eat an ABS until and there goes $700 and programming to fix the problem. Hopefully that isn't the issue but is entirely possible.

 

[Bob4x4]

Top reason why most places will not do anything except loaded calipers on a brake job. Disturbed the seal and run area when the new pads were put on, ANY build up in the brake cylinder cuts the seal. With the phenolic piston sin them and as hit as they get, calipers almost always need rebuilt or swapped when pads are changed. More planned obsolescence.

Hopefully he bled the calipers out and not pushed the fluid back into the system, that practice was discontinued on the LD vehicles +15 years ago. Pushing dirty fluid back into the ABS or MC is just not a good idea, and, the back pressure will eat an ABS until and there goes $700 and programming to fix the problem. Hopefully that isn't the issue but is entirely possible.

Maybe true where you live but not where I live.

 

[cerberusiam]

Maybe true where you live but not where I live.

Not sure what altered perceptions have to do with facts, physics, and generality accepted practices though I am positive the view thru rose colored glasses doesn't change the underlying reality. Best advice would be move before it is too late.

Is there something special you have to do before you push the pistons back into the caliper?

This doesn't change no matter where you live, there are numerous things that SHOULD be done on a 10 year old truck in relationship to the question, there are multiple potential results to "push the pistons back into the caliper". Failing to acknowledge the dependencies and potential results won't change the outcome. Good or bad, that is where most of us live.

 

[JR]

Most shops recommend the gauntlet here when doing brake jobs - pads, calipers, and rotors. Crap rusts so badly here many pad jobs are the result of frozen brake hardware. The road treatment they use here (brine and calcium chloride or magnesium chloride, depending on which they can get cheaper) is a real buzz kill. It's the most corrosive above 15 degrees and high relative humidity, which is most days around here, yet is applied often due to our 100+ inch annual avg snow falls. It's so bad when I do tire rotations on our vehicles I take the time to pull all 4 corners apart and clean all slides and pins and coat necessary parts with anti seize. It's the only shot at getting full life out of a set of pads, most do not do this hence the recommendation by most shops to just replace everything.

Sorry for the irrelevant rant, we are quickly approaching another winter and I have been busy prepping for war - aside from the above I coat the undercarriages annually - a costly and time consuming affair - but really the only option unless you simply stop looking and caring about the underside of your vehicle

 

[Prairie Dog]

I hear ya JR.
They're starting to use that junk more here and the results are devestating not only to vihicles, but also to the tree's the snow blowers deposit it on in our mountain passes. Tons of tree's dead and vehicles are showing rust like never before.
Frankly, we did fine before it and dont need it!

 

[Prairie Dog]

I hear ya JR.
They're starting to use that junk more here and the results are devestating not only to vihicles, but also to the tree's the snow blowers deposit it on in our mountain passes. Tons of tree's dead and vehicles are showing rust like never before.
Frankly, we did fine before it and dont need it!