Mysterious Brake Issue 2015 Ram 1500 Big Horn

[ClarkR]

2015 Ram 1500 5.7 8 speed Big Horn. Had a fading pedal intermittent, drained fluid, refilled, bleed in sequence, seemed to cure the issue. Few months later noticed master cylinder cap, expansion rubber gasket was popping in like a fluid loss. Fluid levels were spot on, no leaks, etc. Pushed the gasket back in and worked fine.

After a few times of this, I got annoyed and called the dealer for an appointment since they have the training, equipment and facility. After 2 visits to them a week at a time the issue still remains. They cleaned the brakes, purged the brake and ABS system, filled and bleed the system. I asked could it be the master cylinder, they said unlikely, they never had to change one on a 1500???

Going to swap the cap and gasket if that doesn't work out, probably will be changing the master cylinder and bleed the system again.

Input welcomed, any ideas as to what would cause the expansion (not swelling like contamination)? Fluid level stays firm, no contaminates, bubbles or droplets in cylinder.

Thanks for your time,
Clark

 

[nlambert182]

My brakes failed on the 2012 2500 that I had and caused me to rear end a Tahoe (totalled it, and caused $8k in damage to my Ram). Different type of brake system but what happened with it was that the hose that goes to the master cylinder had an inner liner that broke loose from the hose. It made it's way into the master cylinder and blocked fluid flow just enough to cause the brakes to stop working.

FCA sent an engineer out to see it and he said that he has seen this before. Don't know if it applies to the 1500 gasser, but might be worth a peek just to see.

 

[brianleleux]

Have you found a resolution to this? My 2014 1500 4x4 Big Horn has an intermittent issue wherein the brake pedal will unexpectedly go to the floor and provide very little braking. Everything will be fine for months and then unexpectedly when pressing the brake pedal there will be no pressure, with no accompanying dashboard warning lights. And it will do it a few times over a couple of weeks, then the issue disappears for a few months. This is truly a safety issue. I've had the brakes replaced, had the fluid levels checked, and even the master cylinder replaced. Still have the issue. It's very scary. I've thought about just getting a new truck, but it seems newer models are having the same issue Life-long Dodge customer here, but this is not an issue that I can continue to take chances with so contemplating moving to a Toyota if Ram cannot diagnose this issue. Really hoping someone has figured out what's causing this.

 

[ClarkR]

Yes, it was the master cylinder. Changed it for stock new, flush and bleed the entire system. Dealer had to flush and bleed the ABS portion. Everything was done April 10, 2023. No intermittent issues nor breaking issues. Plungers/seales (internal piston) on the old one were chewed up. Don't put to much faith in the diag of dealers, you would think with the tech updates and the fancy equipment they could find it, nope, I went in and said swap out stock new, BINGO.