Mushy brake pedal??

[WHazelwood]

I had to make a "panic stop" the other day and noticed the brake pedal felt mushy and went a lot closer to the floor than usual before the anitlock started working. Pedal went so far as to pull the trailer brake cable out of adjustment. Is this because the brake lines are expanding from the hard stop or something else? Pedal is back to normal after the hard stop .

Thanks,

Walt

 

[HOBrian]

How many miles ar on the truck? It might be time to flush the braking system. My pedal gets very touchy after a "panic stop" I have no idea why it does this but it does.

 

[WoodJ]

I think the ABS system is the reason. When the truck goes into ABS (anti-lock brake system) the pedel can go all the way to the floor because it is bypassing fliud.

 

[Money Maker]

you can also boil the fluid and cause air bubbles to get into the system. To flush it out get a couple of quarts of brake fluid and disconnect the brake lines a pump all the fluid out. Then pour in the clean fluid and pump it until you have clean fluid coming out of the lines. You can allow gravity to do it to but pumping is faster. Reconnect the lines and fill the resivor. Now open one bleeder at a time starting with the rear. The calipers will still have some old fluid in them so pump until clean fluid is spewing then make sure all air is out of the caliper before moving to the next one.

 

[BHolm]

One panic stop should not be enough to boil the fluid and cause the pedal to drop, unless of course you were coming down a moutain, towing a big load at 80mph. These trucks also have a different system of supplying "boost" for the power brakes than a gas engine truck. I notice a huge difference in brake feel between the Cummins and the Hemi, the Cummins is much firmer.



I am not familiar enough with the diesels system to say whether or not the pedal drop is "normal". It would however be good practice for all of us to flush the fluid every two years. When I was doing Porsche club events, annual flushes were required to pass tech.



There is also a much quicker and less messy way to get it done. Spend $40 on Motive Products power bleeder. It screws right onto the resevoir cap and uses a pressure tank to force the old fluid out and new fluid in. Makes it a clean one man job, and it takes less than an hour once you get the hang of it. It will save on calipers, ABS units, the pump, and help ensure you do not boil the fluid in a panic stop.

 

[jelag]

I disagree on boiling the fluid... ... in a panic stop you won't get the fluid hot enough to boil it... . however if there is moisture in the system... and it normally collects at the caliper... . you can turn the moisture to steam and that will give you the mushy pedal... that means you need to clean and flush the system with fresh fluid... .

Hope this helps. .