This is my second truck with this issue, and it's my dads truck. He is looking forward to his annual trip to Yuma this February towing my 5th wheel so I got to fix it right. Doing brake work on a 1990 F-250 (the last one was a 1989 F-350) and when all is said and done you have a pedal that is solid when engine is off, but sinks to the floor once you start the engine. Pinching off the ft brake hoses (this is the first time I have done this and don't like it) results in a normal feeling pedal. If any of you all subscribe to IATN, do a search for under Ford Trucks for brakes and you will see this isn't a uncommon problem; many shops have seen this problem or even taken in trucks that another shop has given up on. Many will read along the lines "I have replaced the MC; Calipers Hoses abs valve and booster and still can't get a good pedal under this truck." The repair solution is to replace the MC with one from a F-450; going from a
1 1/8 bore to a 1 5/8 bore. Ford is said to has a notice on this as well as bendix brakes tech line. But for the life of me I can't figure out how a set of brakes that have worked great for 130,000 miles suddenly needs a larger MC. Can anyone enlighten me? PS: I am still researching other solutions to this than the MC- posted
17 years ago