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Posted by copey on Tuesday, March 31, 2009 at 04:48:12 :
In Reply to: OT Soft Brakes in a Ford F350 posted by Ed Tavernier on Monday, March 30, 2009 at 22:43:21 :
ed you fail to mention why you had to bleed the brakes > if have havent changed out any hydraulic components i see no reason to bleed the brakes > what i believe the problem to be is a leaking master cylinder INTERNALY just as Mr Kaegi suggested > now i have a test that i perform on all hydraulic systems you can do it static (engine off) if you take your foot and applie just a ever so slight amount of pressure about 3 to 5 pounds and let your foot float there if the pedal sinks slowly with out additional pressuer the master cylinder is euchered > if the pedal stays up master is good > a Dynamic test is with the engine running and you appply presure a much greater pressure with your foot 100 pounds (about 1500 psi in the lines )and if the pedal sinks the piston in the master cylinder is not sealing under high presurre which means the master cyl is scrap > these are the two ways a "leak down test " in dicate the condition of the abilaty of the cups in the master cylinder to seal and deliver fluid to the lines 1) a low pressure internal leak 2) or one at a high pressure leak in other words ther are two possibilities of master cylinder leak down > On EXTREME cases i have seen bulging flex lines cause a simalar problem but they will bust on the DYNAMIC test (is good to pop them now) a nother situation which is often over looked is brake adjust ment of the reas If you have drums and they are out by miles the fluid has a place to travel and IMATATE SPONGY pedal > ditto on rear disc brakes i have seen that the parking brake set up with cables that work on the calipers that are self adjuat have siezed and take up fluid movemnt moving the calipers Copey ps these opinions and views are not that of this broadcasting network and subject is for mature audiences only , viewer discretion is advised ~ J
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