brakes suck

[tatersf250]

i have a 91 f250 4x4, the other day one of the wheel cylinders busted, i bought new cylinders, new shoes, new drums, put a new vacuum pump on to, now when i step on brake pedal with the pcv valve plugged into brake booster the pedal is soft and goes to the floor, unplug the pcv valve and the pedal is stiff and has decent brakes, now im thinking that the master cylinder or brake booster is bad.....any suggestions?????? thanks

 

[sassyrel]

i have a 91 f250 4x4, the other day one of the wheel cylinders busted, i bought new cylinders, new shoes, new drums, put a new vacuum pump on to, now when i step on brake pedal with the pcv valve plugged into brake booster the pedal is soft and goes to the floor, unplug the pcv valve and the pedal is stiff and has decent brakes, now im thinking that the master cylinder or brake booster is bad.....any suggestions?????? thanks

start the truck..and do you hear,,a vacuum leak inside the cab up where brake pedal rod goes thru firewall??? booster will normally leak if bad...

 

[Matrix37495]

Vacuum pump and PCV valve? Shouldn't you only have one?

Do you mean the check valve on the booster?


I've been fighting a soft pedal in my truck since i got it. Dont know the cure yet, but i'm told its a real pain to get all of the air out. I was told to keep bleeding it.

If you take the vac away fron the booster and get a hard pedal, thats somewhat normal, but it should be near impossible to move and right at the very top. If it's squishy with vacuum, but doesn't sink, you likely still have air somewhere...

If it sinks, you have a leak. If the pedal sink and theres no fluid leaking ANYWHERE, the leak is probably internal in your master. What happens is the fluid leaks past the seals, right back into the reservoir.

 

[tatersf250]

thanks for the info, im going to put a master cylinder on it today sometime, and yes matrix i meant check valve, not pcv valve lol