Nissan Repair: brake problem, rear valve, proportioning valve

Question
QUESTION: Had to change some brake lines and master cylinder.  Now the brake peddle goes 3/4 of the way to the floor before braking.  Have bled the lines with both the car off and running but I am still unable to get the brakes to function properly.

ANSWER: Hi Mike -

Can you tell me what year and what kind of Nissan you have - and which brake lines you replaced and why? was it leaking, or broken? Front or rear, and was it the rubber hose with metal fittings?

Did you "bench bleed" the master cylinder first before installing? If it is just you doing the work, I would suggest to get a bleed kit at the local auto parts store. Only a few dollars and you do not have to remove the master cylinder again to bleed it.

Hope this helps -
aloha
Calvin

---------- FOLLOW-UP ----------

QUESTION: 1997 pathfinder.  Yes we bench bled the master cylinder,  we replaced 3 of 4 metal lines from the proportioning valve to the rear valve.  They more or less rusted through.

Answer
Hi Mike -

There is a chance that some rust particles may have entered the proportioning valve, or the fluid is contaminated with water or some other substance. If you had not flushed it out, I would recommend that.

I remember some Pathys I did it took a few days for the pedal to get higher, can't explain that except for trapped air escaping.

I assume there is no problem with the braking, just grabs low?

Calvin