BRAKE Problem

[2High4U]

I have changed my master cylinder and the prop valve on my brake system it seems to be going to the floor all the time...

no idea on what it could be ive tried bleeding them over and over again getting barely any air if any at all.

anyone who has experinced this problem before let me know I had to miss work because of it today.

When I take the cover off the master cylinder the front bowl kinda shoots up for a second or two also..

Im gonna go and try to crack open the rear line on the prop valve and have someone puch it to the floor.

 

[dremu]

Well, I don't know that the prop valve would cause a low pedal.

First, if you changed masters, be sure to bench bleed it.

Also, I highly recommend the garden sprayer pressure bleeder -- I've done all other methods, vacuum, two-man, speed bleeders, and none are as quick, cheap, easy, relatively un-messy, and reliable as this. Search on 'garden sprayer' here and you'll find what you need.

If your hoses are waaay old and soft, they'll expand when you push the pedal down. I'd give them the old 'visual examination', and if they are cracked or swollen, replace them.

You don't mention if this is a vacuum or hydroboost truck; *generally* when the booster goes out the brake pedal is extremely stiff, but it's a slight possibility that your booster is bad. I'm fortunate to have enough trucks I just swap in a known good one to test this.

OTOH, it really sounds like you need to bleed the system, and are having trouble doing it -- once more, the garden sprayer is your friend.

-- A

 

[dremu]

Oh, and when you do bleed, since you've been playing with the combo valve, be sure to press the rubber button cover thing in to reset the differential sensor between front and rear.

-- A

 

[86Cucvbeater]

i would pull the drums off the rear and check the wheel cylinders for leaks.

 

[BoondocK5]

Everything said in reply so far is right on track, my bets are with he MC needing a good bench bleeding, that usually always solves my soft pedal problems.